![Table of Contents
Preface and Committee
Chapter 1: Chemical Materials Research
Kinetics on the Ultrasonic-Assisted Extraction of Polysaccharides from Limonium bicolor
kunze (Bge.)
X. Song, P. Zhao, Q.H. Meng, Z.S. Tang and C.L. Wang 3
Characterization and Photoluminescence of Sr2B2O5:Eu3+
, Na+
Red Phosphor
L.L. Ying, S.S. Zheng, J.H. Zheng, L.H. Cai and C. Chen 7
Synthesis and Fluorescence Properties of a New Eu(III) Complexes with β-Diketone Ligand
Y.N. Lu, X.Y. Zhao and X. Wang 11
Synthesis and Photochromism Studies of 1-(3,5-dimethyl-4-isoxazole)-2-[2-methyl-5-
naphthyl-3-thienyl] perfluorocyclopentene
X.R. Dong, R.J. Wang, G. Liu and S.Z. Pu 15
Research on Photochromic Materials with Synthesis and Properties of a New
Unsymmetrical Diarylethene 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-
methylene-bromine)phenyl]-3-thienyl} Perfluorocyclopentene
F. Duan and G. Liu 19
Research on Photochromic Compounds with Synthesis and Properties of a Novel
Unsymmetrical Diarylethene with a Benzothiophene and a Pyrrole Group
H.J. Jia, Y.L. Fu and C.B. Fan 23
Research on Photochromic Materials with Synthesis and Properties of 1-(3,5-Dimethyl-4-
isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene
G.M. Liao, D.D. Xue, C.H. Zheng and S.Z. Pu 27
Synthesis and Properties Study of 1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-
phenanthrene)-3-thienyl] perfluorocyclopentene
J.J. Liu, H.J. Jia and S.Z. Pu 31
Research on Photochromic Materials with Synthesis and Application of 1-(2-methyl-3-
benzothienyl)-2-[2-methyl-(5-ethynyl)trimethylsilane-3-thienyl] Perfluorocyclopentene
L.L. Ma, H.Y. Xu and G. Liu 35
Research on Photochromic Compounds with Efficient Synthesis and Photochromic
Properties of 1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]
perfluorocyclopentene
J.J. Song and G. Liu 39
Research on Photochromic Compounds with Efficient Synthesis and Photochromic
Properties of 1-(2-methyl-5-chlorine-3-thienyl)-2-[2-methyl -5-(4-chlorophenyl)-3-thienyl]
Perfluorocyclopentene
F.X. Sun, S.Q. Cui and S.Z. Pu 43
Synthesis, Photochromism and Fluorescent Switch of 1-(2-methyl-1-benzofuran-3-yl)-2-(2-
methyl-5-(4-benzylamine)-3-thienyl)) perfluorocyclopentene
Z.Y. Tian, S.Q. Cui and S.Z. Pu 47
Efficient Synthesis, Photochromism and Fluorescence Properties of a Novel Diarylethene
Bearing a Fluorene
S.J. Xia, X.R. Dong and G. Liu 51
Research on Photochromic Compounds with Synthesis and Photochromism of 1-(2-methyl-
3-benzofuryl)-2-{2-methyl-5-[4-formyloxyethyl (Rhodamine-B)] phenyl-3-thienyl}
Perfluoroyclopentene
D.D. Xue, G.M. Liao, C.H. Zheng and S.Z. Pu 55
Efficient Synthesis, Photochromism and Fluorescence Properties of a Novel Diarylethene
Bearing a Naphthalene
H.Y. Xu, L.L. Ma and S.Z. Pu 59
Synthesis and Properties of 1-[2,5-dimethyl-3-thienyl]-2-[2-methyl-5-(4-pentylphenyl)-3-
thienyl] perfluorocyclopentene
C.C. Zhang, S.S. Wei and S.Z. Pu 63](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-11-320.jpg)
![Kinetics on the ultrasonic-assisted extraction of polysaccharides from
Limonium bicolor Kunze (Bge.)
Xiao Song, Peng Zhao, Qing-hua Meng, Zhi-shu Tang, Chang-li Wang
College of Pharmacy,Shaan Xi University of Chinese Medicine, Xian Yang 712046, China
Zhaopeng65@sina.com
Keywords: Limonium bicolor Kunze (Bge.); polysaccharide; ultrasonic; extraction; dynamics
Abstract. To explore the kinetics parameters in the ultrasonic-assisted extraction from Limonium
bicolor Kunze (Bge.) , the kinetic equation for polysaccharide ultrasonic extraction process was
established with ball model. According to Fick’s second law of diffusion, extraction process was
analysed. The results can provide the valuable theory basis for the technical design and further
research of polysaccharide extraction process.
Introduction
Limonium bicolor Kunze(Bge.) grows and is widely cultivated in Shanxi, Shaanxi,Gansu provinces
of China.The full plant is widely used for the treatment of bleeding,cancer nephritis and other
weakness symptom as a traditional Chinese medicine[1].Polysaccharides, one of the main functional
ingredients in the Limonium bicolor Kunze, has been shown to can signicantly inhibit the growth of
hela cells in vitro[2].
Initially classical hot water extraction (HWE) of polysaccharides from Limonium bicolor Kunze
(Bge.) has been carried out just to compare with microwave-assisted extraction (MAE). It should be
noted that HWE is associated with long extraction time and high temperature. Recently, alternative
extraction techniques such as ultrasonic assisted extraction (UAE) and membrane separation
technology with lower temperature and enhanced yield had also been reported[3,4].
The extraction process, which is concerned with ultrasonic assisted extraction of the effective
compounds from the Limonium bicolor Kunze (Bge.), is quite important and essential in
polysaccharides production. The operating conditions, such as extraction temperature, time, power
etc. considerably influence yields of the polysaccharides. However, to date, no investigation has been
carried out on the extraction process of polysaccharides from Limonium bicolor Kunze (Bge.).
Up to now, suitable values of the operating conditions have to be regulated only according to
conventional experiences accumulated for centuries owing to lack of scientific methods.Thus the aim
of this paper is to increase the ultrasonic assisted extraction rate of polysaccharides from Limonium
bicolor Kunze (Bge.). and choose a suitable extraction reactor, the kinetics of ultrasonic assisted
extraction polysaccharides from Limonium bicolor Kunze (Bge.) is probed.
Methods
Materials Limonium bicolor Kunze (Bge.).was purchased from Xi’an medicine produce market, then
ground to pass through 60 mesh screen and dried at 80℃. Ethanol, phenol, sulfuric acid and ethyl
ether were purchased from Xi’an Chemical Co.( Xi’an,China). All chemicals used in this study were
analytical grade.
Mathematical model The plant extraction process plays a very important role in plant production.
The goal of the plant extraction process is to extract effective compounds from the herb. The real
plant extraction process can be divided into five sub-processes on the whole, that is: (1)Diffusion of
liquid through the film surrounding the particle to the surface of the solid; (2)Diffusion of solvent
through the blanket of remainder to the surface of the un-reacted core; (3)Reaction of solvent with
flavonoids at this reaction surface; (4)Diffusion of products through the remainder to the exterior
surface of the solid; (5)Diffusion of products through the exterior surface into the liquid phase. The
Advanced Materials Research Vol. 1003 (2014) pp 3-6
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![extraction rates of effective compounds, however, are dominated by the diffusion rates. So the herb
extraction process model focuses on the diffusion process of the effective compounds, which first
diffuse to the surface of the herb from the inside of the herb particle and then move to the bulk of the
solution. A rigorous mass transfer model is presented in this paper by analyzing the diffusion process
mechanically.
Fick’s spherical coordinate equation resolution To study the diffusion phenomena following the
ultrasonic-assisted process used in the production of the polysaccharides from Limonium bicolor
Kunze (Bge.), the second Fick’s law written in spherical coordinates has been considered.
∂
∂
+
∂
∂
=
∂
∂
r
c
r
r
c
D
t
c
s
2
2
2
(1)
where Ds is the diffusion coefficient (Ds=D+Du, D is the diffusion coefficient with hot water
extraction, Du is the diffusion coefficient with ultrasonic-assisted extraction), c is the mobile specie
concentration, r is the spherical coordinate, and t is the time.
If r
c
f ⋅
= ，
so
2
2
r
f
D
t
f
s
∂
∂
=
∂
∂ ( 0
,
0 =
= f
r ) (2)
And
R
r = ，
R
r
s
out
out
r
c
S
D
V
t
C
=
∂
∂
−
=
⋅
∂
∂ (3)
Then
( ) ( )
[ ]
{ }
∑
∞
=
∞
∞ −
=
−
−
1
2
2
0 /
exp
/
6
)
/(
)
(
n
st
D
R
n
C
C
C
C π
π (4)
If n=1，so：
( ) ( )
[ ]
2
2
2
0 /
exp
/
6
)
/(
)
( R
t
D
C
C
C
C s
π
π −
=
−
− ∞
∞ (5)
And ：
( ) ( )
[ ] ( )
[ ]
0
2
6
/
ln
/
ln C
C
C
kt
C
C
C −
+
=
− ∞
∞
∞
∞ π , 2
2
/ R
D
k s
π
= (6)
So the total mass transfer equation can be deduced as above (5) and (6). In this work , Du＞＞
D, so we believe Ds≈Du.
Polysaccharide extraction method 15 g Limonium bicolor Kunze (Bge.) (particle radius is about 3
mm) and 300 ml distilled water which had been heated up to 70℃ were added in the 500 mL bottle,
then in every equal minutes, 0.1 mL sample was obtained from the extractionsystem to detcet the
concentration of polysaccharides.
The solution volume of each sample is 0.1mL and the whole extraction process take nine. The
extraction system is changed after sampling, so the need to press (7) measured the concentration of
polysaccharides amended:
( )
[ ]
+
−
−
= ∑
=
9
1
1
.
0
1
1
.
0
300
300
1
n
i
t
n C
C
n
C (7)
where Cn is the n-th sample measured polysaccharide concentration correction value, µg / mL; Ci for
the n samples the measured values of the polysaccharides concentration, µg / mL; n is the sample
number of n = l, 2, ... 9.
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![Parameter estimation By varying the operating conditions (Table 1), the effects of power and time
on the yields of polysaccharides are investigated (the ratio of water to raw material was 20).
Table1 Concentration of polysaccharid at different power（mg/mL）
extraction
time/min
Power /W
40 50 60 70 80
5 0.080 0.109 0.142 0.201 0.221
10 0.132 0.160 0.201 0.245 0.260
15 0.183 0.217 0.261 0.282 0.297
20 0.256 0.328 0.392 0.445 0.470
25 0.304 0.390 0.487 0.538 0.554
30 0.338 0.441 0.546 0.601 0.612
35 0.365 0.479 0.575 0.619 0.643
40 0.388 0.502 0.661 0.679 0.697
45 0.402 0.557 0.663 0.679 0.697
50 0.461 0.556 0.660 0.676 0.659
55 0.459 0.553 0.650 0.649 0.659
Table1 gives the results of the concentration of polysaccharides against the extraction time. It was
found that the higher the power, the greater the extraction rate.In the extraction process, if the
concentration of the polysaccharide extract in a long time remained unchanged, that has been to reach
extraction equilibrium at this time. The concentration can be as a polysaccharide extracted from the
equilibrium concentration（C∞）.
The relation between the extractiontime and the concentration of the polysaccharide
(ln[C∞/(C∞-C)]) can be good understood by the curves plotted in Fig. 1.
Fig.1 Relationship between ln[C∞/（C∞-C）] and t at different power
From Fig.1, the linear regression equation and the corresponding apparent rate constant can be
obtained.As shown as in Table 2.
Table2 Relationship between ln[C∞/（C∞-C）]and t at different temperature
Power/W Linear equation R2 C∞
/mg·mL-1
k×10-4
/s-1
40 ln[C∞/（C∞-C）]=0.0428t- 0.088 0.9945 0.462 7.135
50 ln[C∞/（C∞-C）]= 0.052t-0.167 0.9783 0.557 9.1
60 ln[C∞/（C∞-C）]= 0.057t -0.186 0.9641 0.661 10.72
70 ln[C∞/（C∞-C）]= 0.0683t -0.253 0.9523 0.684 11.44
80 ln[C∞/（C∞-C）]= 0.0723t -0.229 0.9152 0.702 12.08
Advanced Materials Research Vol. 1003 5](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-18-320.jpg)
![As can be seen from Fig.1 and Table 2, it was found that the derivation of the kinetic equation (6)
more in line with the experimental measured data results. The precision of a model can be checked by
the determina -tion coefficient (R2
). The value of the determination coefficient (R2
) was reasonably
close to 1, indicated a high degree of correlation between the observed and predicted values fitting the
resulting equation. With increasing power, the apparent rate constant is gradually increased. It was
indicate that the increase in power will help speed up the dissolution of the polysaccharides.
Conclusions
A general mass transfer model for the polysaccharide from Limonium bicolor Kunze (Bge.) with
ultrasonic-assisted extraction process is established based on the mass transfer principle in this
paper.The results show that the experimental data and kinetic model calculated values are in good
agreement. It can provide a theoretical basis for the design of the polysaccharide from Limonium
bicolor Kunze (Bge.) with ultrasonic-assisted extraction process and some reference value for similar
research.
Acknowledgements
The authors are grateful for the financial supports to this research from Scientific Research Program
Funded by Research Plan in Shaanxi Province, China (No. 2012K19-04-07).
References
[1] X.H.Tang, M.Shen: Lishizhen Medicine and Materia Medica Research, Vol. 8 (2007) , p.1874
(China).
[2] Zhang, L. R, Chen, K. L. Li, N.&Zhou, G. L. (2004). Chemical Journal of Chinese Universities,
11, p.2034-2037 (China) .
[3] R.Hofmann, T.Kappler & C. Posten: Separation and Purification Technology, Vol. 51(2006),
p.303–309.
[4] Z.Hromadkova, A. Ebringerova: Ultrasonics Sonochemistry, Vol.10(2003), p.127–133.
6 Advanced Research on Material Engineering, Electrical Engineering and
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![Characterization and photoluminescence of Sr2B2O5:Eu3+
, Na+
red
phosphor
Lili Ying1, a
, Songsheng Zheng1, b
, Jianghui Zheng 1, c
, Lihan Cai 1, d
,
Chao Chen*,1 2, e
1
School of Energy Research, Xiamen University, Xiamen, 361005, P.R. China
2
School of Physics and Mechanical & Electrical Engineering, Xiamen University, Xiamen,
361005, P.R. China
a
liliying1003@gmail.com, b
songsheng@xmu.edu.cn, c
89zjh@stu.xmu.edu.cn,
d
cailihan02@126.com,e
cchen@xmu.edu.cn
*
Corresponding author. Tel. /fax: +86 592 2182458.
E-mail address: cchen@xmu.edu.cn
Keywords: Phosphors; Luminescence; Borate; Eu3+
;
Abstract. A kind of red emitting phosphor, Sr2B2O5:Eu3+
, Na+
for white light-emitting diodes
(W-LED) was synthesized by high-temperature solid-state reaction method. The characterization
and luminescence properties of the phosphor were investigated. It is found that this phosphor can be
effectively excited by 394 nm near- ultraviolet (n-UV) light, and exhibit bright red emission
centered at 613 nm corresponding to the 5
D0→7
F2 transition of Eu3+
ions. It is shown that the 11
mol% of Eu3+
doping concentration in Sr2B2O5:Eu3+
, Na+
phosphor is optimum, and the
concentration quenching occurs when the Eu3+
concentration is beyond 11 mol%. The concentration
quenching mechanism can be interpreted by the dipole–dipole interaction of Eu3+
ions. The present
work suggests that this novel phosphor is a kind of potential red emitting phosphor.
1. Introduction
Recently, there has been an upsurge in the research of white-light emitting diodes (W-LEDs), being
known as the fourth generation of illumination sources due to their unmatchable benefits , such as
high brightness , high color rendering index (CRI), longer lifetime, high luminescence efficiency, low
power consumption, and environment-friendliness[1, 2]. The presently commercial W-LED is
mainly manufactured by combining a 460nm blue-emitting GaN chip with a yellow- emitting
phosphor of Ce3+
doped yttrium aluminum garnet (YAG:Ce3+
) ,but it suffers from a low
color-rendering index and high correlated color temperature(CCT) owing to red emission deficiency
in the visible spectrum. To solve this problem, a better route has been proposed to fabricate W-LED
by n-UV LED chips coated with RGB (red, green and blue ) tri-color phosphors[3] .There are
several phosphors currently available for W-LED application ,such as blue phosphor
BaMgAl10O17:Eu2+
[4],green phosphor ZnS:Cu+
/Al3+
[5],and red phosphor
Y2O2S:Eu3+
[6].Unfortunately, the sulfide phosphors has low thermal-chemical stability, high
toxicity, and inefficient under the excitation of n-UV light with wavelength of 370-410 nm[7].
Therefore, it is highly desirable to develop a new kind of phosphor with high performance for n-UV
based W-LED applications. Nowadays, the borate-based phosphor has been paid much attention on
account of its low-cost fabrication along with high thermal and chemical stability [8].Examples of
these known borate phosphors are, blue phosphor NaSrBO3:Ce3+
[9], green phosphor
Na3La2(BO3)3:Ce3+
,Tb3+
[1],red phosphor La2SrB10O19:Eu3+
[10]etc.
In this paper, a kind of red emitting phosphor Sr2B2O5: Eu3+
, Na+
has been synthesized by
conventional solid state reaction method at 850 °C. The characterization and photoluminescence
properties of Sr2B2O5: Eu3+
, Na+
phosphor have been discussed extensively; meanwhile the dopant
concentration of Eu3+
was optimized in order to explore highly efficient phosphors.
Advanced Materials Research Vol. 1003 (2014) pp 7-10
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![2. Experimental
A series of Sr2-2xB2O5: xEu3+
, xNa+
phosphors were prepared by high-temperature solid state
reaction method. The starting materials were SrCO3 (AR), Eu2O3 (3N), H3BO3 (AR), and Na2CO3
(AR). The stoichiometric materials were weighed and thoroughly mixed in an agate mortar, then
transferred to a corundum crucible and pre-calcined at 400 °C for 1 h, subsequently sintered at 850 °C
for 3h in air atmosphere.
The crystal structure as well as the phase purity of samples was identified by recording X-ray
diffraction (XRD) patterns using Rigaku Ultima IV diffractometer with Cu Kα radiation (λ = 0.154
nm) operating at 35kV and 15 mA. The surface morphology and particle size of samples were
observed by LEO 1530 scanning electron microscope (SEM). The thermogravimetric analysis (DTA)
and derivative thermogravimetric (DTG) curves dependent temperature were obtained by SDT
Q600 simultaneous thermo-analytical instrument (TA Instruments-Waters LLC, USA).
Photoluminescence excitation and emission spectra were measured by Hitachi F-7000
spectrofluorometer equipped with a 150 W Xenon lamp as an excitation source. All of the
measurements were performed at room temperature.
3. Results and discussion
Fig.1. (a) shows the XRD pattern of the Sr1.78B2O5:0.11Eu3+
, 0.11Na+
sample and the Inorganic
Crystal Structure Database (ICSD) standard pattern. The presenting pattern depicts this phosphor is a
single phase and consistent with JCPDs 73-1930. No impurity peaks were detected in the
experimental range. It can predict that the doped Eu3+
and Na+
didn’t cause any significant change
in host structure and had been efficiently incorporated into the host lattice. According to the ISCD,
the crystal structure of Sr2B2O5 phase belongs to the monoclinic space group P21/c with cell
parameters a=11.850, b=5.350, c=7.710, V=488.79 Å3
. The corresponding cell parameters of the
as-prepared Sr1.78B2O5:0.11Eu3+
, 0.11Na+
from XRD data were refined and calculated to be
a=11.880, b=5.342, c=7.736, V=490.94Å3
.It’s found that cell parameters are slightly different form
the data of JCPDs 73-1930. In view of the distinct ionic radius among Eu3+
(r=108.7pm),
Na+
(r=116pm) and Sr2+
(r=132pm), the incorporation of Eu3+
and Na+
ions is responsible for the
distortion. While, the B3+
ions (r=20pm) are too small for Eu3+
or Na+
to occupy.
Fig.1 (b) shows the TGA/DTG results of the stoichiometric mixture of SrCO3, Eu2O3, H3BO3 and
Na2CO3 heated from room temperature up to 850 °C with a heating rate of 10 °C /min in air. The
weight loss before 600 °C was mainly caused by the release of CO2 and H2O from the
decomposition of the starting materials. The DTG curve has a conspicuous endothermic peak at
around 850 °C, corresponding to a quick weight loss in the interval of that moment temperature,
which indicates to the formation of Sr2B2O5 crystalline phase. Thus, the sintering temperature of
as-synthesized sample was determined to be 850 °Which is much lower than that of
Sr3B2O6:Eu3+
,Na+[
11] .The inset of SEM image in fig.1.(b)reveals the surface morphology of the
as-synthesized sample and the well-dispersed particles with size ranging in 3–7μm.
Fig.1. (a) XRD patterns of Sr1.78B2O5:0.11Eu3+
:0.11Na+
phosphor and standard of JCPDs card
No.73-1930(b) The TGA/DTG curves of as-synthesized sample with a heating rate of 10 °C /min in
air. Inset is the SEM image of Sr1.78B2O5:0.11Eu3+
:0.11Na+
phosphor
8 Advanced Research on Material Engineering, Electrical Engineering and
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![Fig.2. (a) Excitation spectrum (λem=613 nm) and the emission intensity of Sr2−2xB2O5:xEu3+
, xNa+
phosphor with different Eu3+
concentrations (λex=394 nm). (b)The dependence of lgI/x on lgx in the
selected Sr2B2O5: Eu3+
, Na+
phosphors (λex=394nm).
The excitation spectrum by monitoring the emission at 613 nm (5
D0→7
F2) from Eu3+
ions is
depicted in Fig.2 (a). It can be seen that the excitation spectrum consists of a series of sharp peaks at
362nm (7
F0→5
D4), 381nm (7
F0→5
L7), 394nm (7
F0→5
L6), 415nm (7
F0→5
D3), and 465nm
(7
F0→5
D2) .The peak intensity at 394nm is the highest one. The emission spectra of
Sr1.78B2O5:0.11Eu3+
,0.11Na+
phosphor under the 394 nm excitation is shown in Fig.2 (a).There are
four peaks located at 580nm,593nm,613nm, 621nm,which are attributed to the
5
D0→7
F0,5
D0→7
F1 ,5
D0→7
F2 and 5
D0→7
F2 transitions of Eu3+
ions respectively and the red
emission at 613nm is dominated. Therefore, Sr2B2O5: Eu3+
, Na+
phosphor can be well excited by
394nm and emit red light.
The emission spectra of Sr2−2xB2O5:xEu3+
, xNa+
phosphor with various Eu3+
concentrations
excited by 394 nm near UV light are shown in Fig.2 (a), which display the similar spectrum except
for the luminescence intensity. It is confirmed that the crystalline phase did not change a lot with
doping different Eu3+
concentrations. The highest integrated emission intensity is noted at the Eu3+
concentration of x=0.11, which is taken as the critical concentration. Lower doping concentrations
can lead to weak luminescence and higher dopants will cause concentration quenching of the Eu3+
emission.
Since the fluorescence mechanism of Eu3+
in Sr2B2O5:Eu3+
, Na+
phosphors is the electric
multiple-multiple interaction by Dexter theory[12].If the energy transfer occurs between the same
sort of activators, then the intensity of multipolar interaction can be determined from the change of
the emission intensity from the emitting level which has multipolar interaction. The emission
intensity (I) per activator ion is given by the equation [13, 14]:
I/x=K [1+β(x) Q/3
]-1
. (1)
Where I is the emission intensity of Sr2−2xB2O5:xEu3+
, xNa+
phosphor, x is the activator Eu3+
concentration; Q =6, 8, or 10 is for dipole–dipole (d–d), dipole–quadrupole (d–p), or quadrupole–
quadrupole (q–q) interaction, respectively; and K and β are constants for the same excitation
condition for a given host crystal. When x is larger than the critical quenching concentration, Eq. (1)
can approximately be simplified as Eq. (2) for β(x) Q/3
>>1, where A is a constant.
lg(I/x)=A-Q/3lgx. (2)
Since the critical concentration of Eu3+
has been determined as 11mol%, the dependence of the
emission intensity of the as-synthesized phosphors on corresponding concentration of Eu3+
which is
not less than the critical concentration is determined. The plot of lgI/x as a function of lgx is shown
Advanced Materials Research Vol. 1003 9](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-22-320.jpg)
![in Fig.2. (b). It shows that the dependence of lgI/x on lgx is linear and the slope of the fitting line is
-1.917.According to the Eq. (2), the value of Q can be calculated as 5.751, which is approximately 6.
It indicates that the dipole–dipole (d–d) interaction is the main concentration quenching mechanism
of Eu3+
emission in Sr2B2O5: Eu3+
, Na+
phosphors.
4. Conclusions
In conclusion, the Sr2B2O5:Eu3+
, Na+
phosphors have been synthesized by solid-state reaction. The
emission spectrum indicates that the as-synthesized phosphor emits bright red emission centered at
613nm under 394nm excitation. And the optimum concentration of Eu3+
is testified to be 11mol%.
The concentration quenching mechanism of Eu3+
ions in Sr2B2O5:Eu3+
, Na+
phosphor is the dipole–
dipole interaction. Therefore, Sr2B2O5:Eu3+
, Na+
phosphor is a promising red phosphor for near-UV
LED applications.
Acknowledgements
This work was financially supported by National Natural Science Foundation of China (No.
61076056).
References
[1] M. Yang, L. Liu, F. Chen, Materials Letters, 88 (2012) 116-118.
[2] A.A. Reddy, S. Das, A. Goel, R. Sen, R.e. Siegel, L.s. Mafra, G.V. Prakash, J.M.F. Ferreira, AIP
Advances, 3 (2013) 022126.
[3] J.K. Sheu, S.J. Chang, C.H. Kuo, Y.K. Su, L.W.Wu, IEEE Photonics Technology Letters, 15
(2003) 18-20.
[4] S.W. Ko, D. Shin, Journal of Electroceramics, 23 (2008) 410-414.
[5] A. Suzuki, S. Shionoya, Journal of the Physical Society of Japan, 31 (1971) 1455-1461.
[6] S.-H. Рагк, S.-i. Mho, K.-W. Lee, Notes, 17 (1996) 487.
[7] P. Li, Z. Xu, S. Zhao, F. Zhang, Y. Wang, Materials Research Bulletin, 47 (2012) 3825-3829.
[8] L. Cai, L. Ying, J. Zheng, B. Fan, R. Chen, C. Chen, Ceramics International, 40 (2014)
6913-6918.
[9] W.-R. Liu, C.-H. Huang, C.-P. Wu, Y.-C. Chiu, Y.-T. Yeh, T.-M. Chen, Journal of Materials
Chemistry, 21 (2011) 6869.
[10] R. Guo, S. Tang, B. Cheng, D. Tan, Journal of Luminescence, 138 (2013) 170-173.
[11] R. Wang , J. Xu , C. Chen Chinese journal of luminescence, 30 (2011-10) 983-987.
[12] D.L. Dexter, J.H. Schulman, The Journal of Chemical Physics, 22 (1954) 1063.
[13] I.G.V. Uitert, Journal of the electrochemical society, 114 (1967) 1048-1053.
[14] L. Ozawa, P.M. Jaffe, Journal of the electrochemical society, 118 (1971) 1678-1679.
10 Advanced Research on Material Engineering, Electrical Engineering and
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![Synthesis and Fluorescence Properties of a New Eu(III) Complexes with
β-Diketone Ligand
Ya Nan Lu a
, Xiong Yan Zhao b*
, and Xin Wang c
College of Material Science and Engineering, Hebei University of Science and Technology,
Shijiazhuang, 050018, P. R. China
a
email: 370555496@qq.com, b*
email: zhaoxy66@126.com, c
email: xin.wang.hebust@gmail.com
Keywords: β-diketone, rare earth ions, thermal stability, fluorescence property
Abstract. A novel β-diketone 4-[4-(Dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD) and its
corresponding Eu3+
complex with 1,10-phenanthroline were synthesized. The structure, thermal
behaviour and fluorescence property of the complex was characterized by Fourier Transform
Infrared (FT-IR), thermal gravimetric analysis (TGA) and fluorescence spectrophotometer. The
fluorescence characterization shown that the addition of β-diketone and 1,10-phenanthroline
enhance the fluorescence intensity of the complex. Eu3+
complex was considered to be a valuable
organic light-emitting material with bright red fluorescence because of its strong emission band.
Furthermore, the thermal stability characterizarion shows that the obtained rare earth β-diketone
complexes have good thermostability.
Introduction
Rare earth complex is a kind of luminescent materials that has unique photoluminescence
properties, good monochromaticity and high fluorescence intensity which has attracted increasing
attention recent years[1]. Rare earthEu3+
and Tb3+
have excellent fluorescence and
monochromaticity, their f→f transition appears in the visible area[2-3], but the strength and
efficiency of luminescence are reduced because of their f→f transition are forbidden. Therefore, a
new type of organic ligands that have larger π electron conjugated system, strong UV absorption,
above all, can coordination and excitation rare earth ions need to be designed and prepared[4-5].
β-diketone with a high absorption coefficient and appropriate conjugated system is a kind of good
organic chelating ligand, it can sensitize and has strong coordination ability with rare earth
ions[6-7]. Generally, a second ligand is added to meet the coordination number of center rare earth
ions[8-10]. In order to obtain new rare earth fluorescence materials with effective luminescent
properties, a new type of β-diketone ligand was synthesized in this work. Research shows that
adding aromatic rings with nitrogen atoms, such as 1,10-phenanthroline can enhance rare earth’s
fluorescence. We have synthesized a novel rare-earth complex possessing β-diketone and
1,10-phenanthroline in this research and its fluorescence properties were discussed in details.
Experimental
Materials. 4-Aminoacetophenone(99%) was obtained from Alfa Aesar, benzylbromide(CP) and
europium oxide(Eu2O3, EP) were both purchased from Sinopharm Chemical Reagent Co. Ltd,
1,10-phenanthroline(Phen) and other reagents were commercial products without further
purification. Europium chlorides were obtained by dissolving its oxides (Eu2O3) into concentrated
hydrochloric acid.
Advanced Materials Research Vol. 1003 (2014) pp 11-14
© (2014) Trans Tech Publications, Switzerland
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![Synthesis of 1-[4-(dibenzylamino)phenyl]ethanone(DBMPE). 4-aminoacetophenone(12.16 g
90mmol), benzylbromide(34.2 g 0.2 mol), K2CO3(27.6 g) and KI(0.5 g) were all dissolved in
appropriate amount of DMF(300ml), added the solution into a 500 ml three-necked bottle with
stirring at 120 ℃ for 48 hours. The supernatant was left after experiment and the solvent was
removed by reduced pressure distillation. The final products were obtained by washing and
recrystallized by ethanol.
Synthesis of 4-[4-(dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD). 15 mmol ethyl acetate and
10 mmol DBMPE were added into a 100 ml three necked bottle with stirring under nitrogen at 20℃
for 15 minutes. 50 mmol sodium cyanide were added into the bottle and the reaction temperature
was fixed at 20℃. After stirring of 5 hours at a constant speed, the final products were obtained
followed by pH adjustment, dichloromethane extraction, water elimination, vacuum-rotary
evaporation and separation and purification by silica gel column chromatography.
Synthesis of Eu(DPD)3phen. 4.5 mmol DPD, 1,10-phenanthroline and sodium hydroxide were
dissolved in ethanol, respectively. All the three solutions were blended and poured into a three
necked bottle with a condenser. After reacted at 60℃ for 20 minutes, europium chlorides were
added into the bottle by drop wise manner. After reacted for 2 hours, the Eu(DPD)3phen precipitate
were obtained by vacuum filtration.
Results and Discussion
Structure analysis of the rare earth complexes. The FTIR spectrum of complex was shown in
Fig.1. The absorption band observed at 1580cm-1
is the stretching vibration peak of C=O in
β-diketone. The band at 1424.6 and 1495.8cm−1
are attributed to the bending vibration of C-H and
combined effect of stretching vibration of C=O, C=N in Phen, respectively. In addition, two bands
at 842.4 and 729.8cm-1
are attributed to the bending vibration of hydrogen atoms on benzene rings.
After β-diketone was chelated with rare earth ion, the bands of C=O, C=N, C=C were weaken by
conjugate structure of C=O-Eu and lead to vibration peak redshift. The bands at 458 and 530.8 cm-1
are attributed to the stretching vibration of Eu-O and Eu-N in complex.
3500 3000 2500 2000 1500 1000 500
0
20
40
60
80
100
1399.1
1495.8
1580.3
842.4
729.8
458
Transmittance(%)
Wavenumbers(cm-1)
Fig. 1 FT-IR spectra of the complex
12 Advanced Research on Material Engineering, Electrical Engineering and
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![200 300 400 500 600 700
0
1000
2000
3000
4000
5000
6000
7000
5
D0
→
7
F4
5
D0
→
7
F3
5
D0
→
7
F2
5
D0
→
7
F1
5
D0
→
7
F0
Fluorescence
Intensity(a.u.)
Wavelength(nm)
Fig.3 Fluorescence spectra of complex Eu(DPD)3phen
Conclusions
In this work, a novel β-diketone ligand 4-[4-(Dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD)
and its corresponding complex Eu(DPD)3phen were synthesized and characterized. The FT-IR
spectrum indicates that the oxygen atoms of β-diketone and the nitrogen atoms of phen were
coordinated to the Eu3+
ion. The excitation spectra and emission spectra show Eu3+
complex has
strong fluorescence at 613 nm and emits a strong red luminescence. Due to its good thermal
stability, it can be used as promising candidates for applications in organic light-emitting materials.
Acknowledgements
The Project was supported by the Hebei Province Science and Technology Support Project (Grant
No. 14210309D).
References
[1] S.S. Yang, Q.S. Song, K. Gao: Solid State Sciences Vol. 34 (2014), p. 17-23
[2] Y.J. Li, B. Yan, Y. Li: Journal of Solid State Chemistry Vol. 183 (2010), p. 871-877
[3] A. Ege, M. Ayvacikli, O. Dinçer, et al: Journal of Luminescence Journal of Luminescence Vol.
143 (2013), p. 653-656
[4] D.Z. Ma, Y.Q. Wu, X. Zuo: Materials Letters Vol. 59 (2005), p. 3678-3681
[5] R.R. Tang, W. Zhang, Y.M. Luo, et al: Journal of rare earths Vol. 27 (2009), p. 361-367
[6] X.W. Liu, N. Wang, Q.L. Suo: Journal of rare earths Vol. 26 (2008), p. 778-782
[7] X.W. Liu, J.D. Jiang, S.L. Yong, et al: Journal of rare earths Vol. 30 (2012), p. 520-523
[8] H.F. Jiu, G.D. Liu, Z.J. Zhang, et al: Journal of rare earths Vol. 29 (2011), p. 741-745
[9] Y.F. Zhang, Z. Xu, Y.G. Lü, et al: Journal of rare earths Vol. 25 (2007), p. 143-147
[10] Y.G. Lü, G. Li, C.H. Shi, et al: Transaction of Nonferrous Metals Society of China Vol. 20
(2010), p. 2336-2339
14 Advanced Research on Material Engineering, Electrical Engineering and
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![Synthesis and Photochromism studies of
1-(3,5-dimethyl-4-isoxazole)-2-[2-methyl-5-naphthyl-3-thienyl]
perfluorocyclopentene
Xiaorong Dong, Renjie Wang*, Gang Liu and Shouzhi Pu
Jiangxi key laboratory of Organic Chemistry, Jiangxi Science & Technologe Normal University,
Nanchang 330013, P. R. China
bio-wrj@163.com
Keywords: Diarylethene; Photochromism; Fatigue Resistance; Kinetic;
Abstract. A new class of unsymmetrical photochromic diarylethene bearing an isoxazole moiety
was synthesized. Its photochemical properties, including photochromic behavior and kinetics, have
been investigated systematically. The result indicated that the Diarylethene 1a changed the color
from colorless to pink irradiation with 297 nm UV light, in which absorption maxima were
observed at 522 nm in hexane. The photochromic reaction kinetics indicated that the cyclization
processes of 1a belong to the zeroth order reaction and the cycloreversion process belong to the first
order reaction.
Introduction
Photochromism, a photoinduced reversible reaction between two isomers, is one of the essential
photochemical reactions to facilitate the reversible fluorescence switching process in synthetic
molecules as well as fluorescence proteins [1-4]. Photochromic dithienylethenes are considered to
be among the most promising systems for applications in optical memory media and switching
devices due to their excellent photochromic properties coupled with thermal stability, fatigue
resistance, and sensitivity [5-9]. Therefore, current research interest is focused on the introduction
of heterocycles to obtain novel photochromic materials with excellent properties.
In the past several decades, numerous studies have focused on molecular design, especially the
symmetric and asymmetric synthesis of organic frameworks in diarylethenes with different
heteroaryl units such as thiophene or benzothiophene[10-12]. It has been revealed that the aryl
moieties and the functional substituents have critical effects on photochromic properties. In
particular, diarylethenes with different substituted ring systems have been of considerable interest,
which different substituted ring could be resulted in different color change before and after light
irradiation.
In this research work, a new unsymmetrical photochromic diarylethene bearing an isoxazole
moiety compound 1a was synthesized and its photochemical properties, such as photochromism in
solution as well as in PMMA amorphous film can be easily obtained. The photochromic reaction of
diarylethene 1a is shown in Scheme 1.
F
F
F
F
F
F
S
N
O
F
F
F
F
F
F
S
N
O
UV
Vis
1o 1c
Scheme 1. Photochromism of diarylethene 1a.
Experiments
Synthesis of diarylethene 1a. Synthetic route for diarylethene 1a is shown in Scheme 2.
Diarylethene 1a was characterized by 1
H NMR . 1
H NMR (400 MHz, CDCl3): δ 2.12 (s, 3H, -CH3),
Advanced Materials Research Vol. 1003 (2014) pp 15-18
© (2014) Trans Tech Publications, Switzerland
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![and k of cycloreversion (kc-o, 10-3
) process of 1c were 1.01 mol L-1
s-1
and 1.47 s-1
in hexane,
respectively.
0 10 20 30 40
0.01
0.02
0.03
0.04
0.05
0.06
(A)
Abs
Time (s)
R=0.99593
Y = 0.01606 + 0.00101 * X
0 5 10 15 20 25
0.98
0.99
1.00
1.01
1.02
-log(Abs)
Time (s)
(B)
R=0.99753
Y = 0.97959 + 0.00147 * X
Fig. 2 The cyclization kinetics (A) and cycloreversion kinetics (B) of compound 1a in hexane.
The fatigue resistance of 1a in solution and PMMA film. The fatigue resistance [13-14] of
diarylethene 1a was tested in both hexane and PMMA film at room temperature, and the result is
presented in Fig. 3. In hexane, the coloration and decoloration cycles of 1a could repeat more than
100 times with the degradation of 35% for 1c. After repeating 200 times in PMMA film,
diarylethene 1a still exhibited favorable photochromism with the degradation of 30% for 1c.
Therefore, diarylethene with an isoxazole moiety exhibited fatigue resistance in both hexane and
PMMA film.
20 40 60 80 100
0.00
0.25
0.50
0.75
1.00
A/A
0
(%)
Repeat Cycles
(A)
50 100 150 200
0.00
0.25
0.50
0.75
1.00
A/A
0
(%)
Repeat Cycles
(B)
Fig. 3 Fatigue resistance of diarylethene 1a in air atmosphere at room temperature in hexane (A)
and in PMMA film (B). Initial absorbance of the sample was fixed to 1.0.
Summary
A new unsymmetrical photochromic diarylethene was synthesized. Its photochromic property and
the kinetic reactions were investigated by UV-Vis spectra in hexane solution. The present result
indicated that the diarylethene has good photochromic properties. Furthermore, the compound also
exhibited fatigue resistance.
Acknowledgment
The authors are grateful for the financial support from the National Natural Science Foundation of
China (21262015).
Advanced Materials Research Vol. 1003 17](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-30-320.jpg)
![References
[1] M.-M. Russew and S. Hecht: Adv. Mater. Vol. 22 (2010), p. 3348
[2] Q. Wei and A. Wei: Chem.–Eur. J. Vol. 17 (2011), p. 1080
[3] M. Irie, T. Sasaki, N. Tamai and T. Kawai: Nature, Vol. 420 (2002), p. 759
[4] A. Bianco, G. Lanzani and C. Bertarelli: Photonics Rev. Vol. 5 (2011), p. 711
[5] M. Irie: Chem Rev. Vol. 100 (2000), p. 1685
[6] S. Kobatake and Y. Terakawa: Tetrahedron Lett. Vol. 52 (2011), p. 1905
[7] H. Tian, S.J. Yang: Chem Soc Rev. Vol. 33 (2004), p. 85
[8] H. Tian, Y.L. Feng: J Mater Chem. Vol. 18(2008), p. 1617
[9] A. Bianco, C. Bertarelli and G. Zerbi: Chem Mater. Vol. 17 (2005), p. 869
[10] S.Z. Pu, J.K. Xu, Q. Xiao and B. Chen: Mater. Lett. Vol. 60 (2006), p. 685
[11] S. Kobatake, H. Muto, T. Ishikawa and M. Irie: Nature Vol. 446 (2007), p. 778
[12] X.D. Deng and L.S. Liebeskind: J. Am. Chem. Soc. Vol. 123 (2001), p. 7703
[13] H. Tian and S.J. Yang: Chem. Soc. Rev. 33 (2004), p. 85
[14] M. Irie: Chem. Rev. 100 (2000), p. 1685
18 Advanced Research on Material Engineering, Electrical Engineering and
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![Research on Photochromic Materials with Synthesis and Properties of a
New Unsymmetrical Diarylethene
1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)p
henyl]-3-thienyl} Perfluorocyclopentene
Fang Duan and Gang Liu*
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University,
Nanchang 330013, P. R. China
liugang0926@163.com
Keywords: Diarylethene; Photochromism; Kinetics; Fluorescence.
Abstract. A new photochromic diarylethene having a pyrrole unit, which is named
1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)phenyl]-3-thienyl}perflu
orocyclopentene, was designed and constructed successfully. And its properties have been
discussed systematically, including photochromic, fluorescence switch and kinetics experiments in
acetonitrile solution. The results showed that its photochromic behaviors could be modulated by
UV/Vis light, changing from colorless to blue in acetonitrile solution. What is more, the kinetic
experiments illustrated that the cyclization/cycloreversion process of this compound was
determined to be the zeroth/first reaction.
Introduction
Photochromic materials are a family of compounds which can undergo reversible photo-switches
between two different isomers having remarkably various properties [1]. Photochromic compounds
are the most promising candidates for photoelectronic applications, such as optical memory,
chemical sensor, and molecular switching, because of their thermally-irreversible and
fatigue-resistant photoisomerization performances [2]. During the past decades, the majority of the
study work reported has been devoted to the development of these molecules and investigative
studies of their fundamental properties [3-5]. Up to date, design and synthesis of new photochromic
compounds is an active area of research, and many publications concerning synthesis and
investigation of the properties of diarylethenes with the heterocyclic aryl rings have been reported
[6–8]. Among these novel photochromic diarylethenes, there are few examples of photochromic
diarylethenes bearing pyrrole rings. This special structural characteristic may be in favor of
photochromic reaction. On the basis of these considerations, we design a new class of hybrid
photochromic diarylethene derivatives bearing a pyrrole moiety.
In this paper, we designed and synthesized a new diarylethene, namely
1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)phenyl]-3-thienyl}perflu
orocyclopentene 1o. Its photochromic reactivity, kinetics and fluorescence were investigated in
detail. The photochromic reaction of diarylethene 1o is shown in Scheme 1.
N
NC
F
F
F
F
F F
S
Br
UV
Vis
N
NC
F
F
F
F
F F
S
Br
1o 1c
Scheme 1. Photoisomerization of 1o
Advanced Materials Research Vol. 1003 (2014) pp 19-22
© (2014) Trans Tech Publications, Switzerland
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![Experiments.
Synthsis of diarylethene 1o. The target diarylethenes were synthesized by the method as shown in
Scheme 2. It was synthesized according to the similar procedure of Pu et al [9]. The structure of
compound 1o was characterized by 1
H NMR spectroscopy. NMR spectra were recorded on Bruker
AV400 (400 MHz) spectrometer with CDCl3 as the solvent and tetramethylsilane as an internal
standard. 1
H NMR (400 MHz, CDCl3, TMS): δ 1.70 (s, 3H,-CH3), 1.90 (s, 3H,-CH3), 3.54 (s,
3H,-CH3),4.53 (s, 2H,-CH2), 6.86 (s, 1H, thiophene-H), 7.19 (s, 1H, thiophene-H), 7.34 (d, 2H, J =
8.0 Hz, benzene-H), 7.47(d, 2H, J = 8.0 Hz, benzene-H).
N
NC
Br2
N
NC
Br
C5F8
N
NC
F
F
F
F
F
F F
S
Br
CHO
N
NC
F
F
F
F
F F
S
N
NC
F
F
F
F
F F
S
CHO
NaBH4
THF
N
NC
F
F
F
F
F F
S
CH2OH
LiBr
THF
DMC
三
三
三
三乙
乙
乙
乙胺
胺
胺
胺 N
NC
F
F
F
F
F F
S
Br
S
Br
Glycol
Toluene
Reflux
6
O
O
O
O
Py, TsOH
Acetone
H2O
Reflux
8
7
2 3 4
5
9 1o
Scheme 2. Synthesis of diarylethene 1o
Results and discussion
Photochromism of diarylethene 1o in acetonitrile solution. The diarylethene 1o exhibited good
photochromic properties and could be toggled between its colorless ring-open and colored
ring-closed forms by alternate irradiation with appropriate wavelengths of light. The absorption
spectral changes in acetonitrile are shown in Fig. 1. The open ring isomer had an absorption
maximum at 301 nm which was arisen from π→π*
transition [10] . Upon irradiation with 297 nm
light, the colorless solution of 1o turned to blue due to the appearance of a new broad absorption
band at λ = 617 nm defined as the formation of the closed-ring isomer 1c. Then, the blue colored
solution reverted to colorless upon irradiation with visible light (λ > 450 nm), indicating that 1c
returned to the initial state 1o, and a clear isosbestic point was observed at 322 nm. From the above
description, we can easily get a conclusion that both open-ring isomer and closed-ring isomer of this
diarylethene were stable in solution at room temperature.
Fig. 1 Absorption spectra upon alternating irradiation with UV-Vis light of the compound 1o in
acetonitrile (2.0 × 10-5
mol/L).
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![Photochromic reaction kinetics in acetonitrile solution. The photochromic cyclization and
cycloreversion kinetics of this diarylethene in acetonitrile were determined by UV-Vis spectra upon
alternating irradiation with appropriate wavelength UV and visible light at room temperature. The
cyclization and cycloreversion curves of compound 1 are shown in Fig. 2, respectively. It can be
seen that the relationships between the absorbance and exposal time have good linearity upon
irradiation with 297 nm light (Fig. 2A). It is suggesting that the cyclization process of compound 1o
belong to the zeroth order reaction when open-ring isomer changed to closed-ring isomer. At the
same time, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time
also behave perfect linearity, as shown in Fig.2 (B), indicating that the cycloreversion process
belong to the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3
) of
diarylethene 1c can be easily obtained in solution, respectively.
0 10 20 30 40
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
A
Y=-0.00213+0.00162*X
R=0.99299
Absorbance
Time/s
0 10 20 30 40 50 60
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
Y=0.79934+0.02121*X
R=0.9973
-log(
Abs)
Time/s
B
Fig. 2 The cyclization (A) and cycloreversion (B) kinetics of compound 1o in acetonitrile.
Fluorescence of diarylethene . Fluorescent properties can be useful not only in molecularscale
optoelectronics, but for digital photoswitching of fluorescence. In this work, the fluorescence
properties of the diarylethene1o in solution (2 × 10-5
mol/L) was measured using a Hitachi F-4600
spectrophotometer, and the breadths of excitation and emission were selected 5.0 nm and 10.0 nm.
The fluorescence excitation and emission spectra of 1o in acetonitrile (2 × 10-5
mol/L) at room
temperature was illustrated in Fig. 3. From Fig. 3, we can clearly see that the acetonitrile of
diarylethene 1o exhibited relatively strong fluorescence at 368 nm when excited at 240 nm. The
Stokes shift of the fluorescence was relatively large and the fluorescence spectral edge showed a
red-shift in comparison with the absorption edge. This kind of large Stokes shift has already been
discussed in detail by Sekiya and coworkers [11].
200 250 300 350
0
500
1000
1500
350 400 450 500 550
0
1000
2000
3000
4000
5000
Emission
Intensity
(a.u.)
Ex
Wavelength/nm
Em
Fig. 3 Excitation spectra (-) and fluorescence spectra (-) of 1o in acetonitrile
Fig.4 shows the fluorescence spectral changes of 1o. Diarylethene 1o exhibited good fluorescence
in acetonitrile solution, and the values are 368 nm. The fluorescence intensity of diarylethene 1o
decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer
in acetonitrile. The back irradiation by appropriate wavelength visible light regenerated the
open-ring form of diarylethene 1o and recovered the original emission spectra. The incomplete
Advanced Materials Research Vol. 1003 21](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-34-320.jpg)
![cyclization reaction and the existence of parallel conformations may be the main cause for the
moderate change in fluorescence induced by photoirradiation. The reversible changes of the
emission intensity of diarylethene 1o are useful for application as the fluorescence switches.
360 370 380 390 400
500
1000
1500
2000
2500
3000
3500
Emission
Intensity
(a.u.)
Wavelength /nm
Vis UV
Fig. 4 Fluorescence spectra of diarylethene 1o in acetonitrile (2.0 × 10-5
mol/L) excited at 240 nm
upon irradiation with 297 nm UV light at room temperature.
Summary
In conclusion, a novel diarylethene was synthesized to investigate its photochromism, kinetic and
fluorescence. Diarylethene 1o exhibited photochromism in acetonitrile solution and relatively
strong fluorescence at 368 nm when excited at 240 nm. The results will be helpful for the synthesis
of efficient photoactive diarylethene derivatives with fluorescence switches.
Acknowledgment
The authors are grateful for the financial support from the National Natural Science Foundation of
China (21262015).
References
[1] J. J. Zhang, Q. Zou and H. Tian: Adv. Mater. Vol. 24 (2012), p. 1
[2] M. Natali and S. Giordani: Chem. Soc. Rev. Vol. 41 (2012), p. 4010
[3] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu and T.S. Yang: Dyes and Pigments Vol. 90 (2011), p. 71
[4] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron Vol. 67 (2011), p. 1438
[5] G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980
[6] H. Nishi and S. Kobatake: Macromolecules. Vol. 41 (2008), p. 3995
[7] Q. F. Luo, H. Cheng and H. Tian: Polylm. Chem. Vol. 2 (2011), p. 2435
[8] R. J. Wang, S. Z. Pu, G. Liu, S. Q. Cui and H. Li: Tetrahedron Lett. Vol. 54 (2013), p. 5307
[9] S. Z. Pu, G. Liu, and J. K. Xu. Org. Lett. Vol. 9(2007), p.2139.
[10]Z.X. Li, L.Y. Liao, W. Sun, C.H. Xu, C. Zhang, C.J. Fang and C.H. Yan: J. Phys. Chem. C.
Vol. 112 (2008), p. 5190S.
[11]N. Tanaka, C. Okabe, K. Sakota, and M. Irie:J. Mol. Struct. Elsevier, Amsterdam. vol.
616(2002),p. 113.
22 Advanced Research on Material Engineering, Electrical Engineering and
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![Research on Photochromic Compounds with Synthesis and Properties
of a Novel Unsymmetrical Diarylethene with a Benzothiophene and a
Pyrrole Group
Hongjing Jia, Yinglong Fu and Congbin Fan *
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University,
Nanchang 330013, P. R. China
congbinfan@163.com
Keywords: Unsymmetrical Diarylethene, Photochromic, Kinetics, Optical Storage.
Abstract. A new unsymmetrical photochromic diarylethene 1o, which is named
[1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)]perfluorocyclopentene, was
synthesized. We used it to accomplish recording by optical storage technology as memory medium.
Then its photochromic both in hexane solution and in PMMA film and kinetics experiment were
investigated in detail. The result indicated that this diarylethene had good thermal stability and
exhibited reversible photochromism, changing the color from colorless to violet in hexane solution
upon appropriate irradiation with 297 nm UV light, respectively. What is more, the kinetic
experiments illustrated that the cyclization/cycloreversion process of this compound was determined
to be the zeroth/first reaction. The results demonstrated that the unsymmetrical diarylethene
compound 1o, which we have synthesized, had attractive properties for potential application in
optical storage.
Introduction
During the past several decades, there have been reported various kinds of photochromic
compounds, such as azobenzenes [1], spirobenzopyrans [2], fulgides [3], and so on. Among them,
diarylethene derivatives are regarded as the best promising candidates for such devices, due to their
good thermal stability and remarkable fatigue resistant performances required for optoelectronic
applications [4,5], representatively their potential applications including optoelectronics such as
optical recording, photo-switching, and full-color display devices [6-8]. Therefore, it is especially
important to synthesize diarylethene derivatives and research their structural features.
In previous papers, a large number of publications concerning synthesis and investigation of their
photochromic properties of diarylethene have been reported [9,10]. To the best of our knowledge,
most of the papers concentrated on symmetrical compound. However, there are few publications
report photochromic unsymmetrical hybrid diarylethene derivatives with benzothiophene and pyrrole
moieties.
According to the above aspects, in this work, a new unsymmetrical diarylethenes
1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)perfluorocyclopentene 1o was
synthesized. Then, the photochromic properties and kinetics experiment were discussed and
investigated in detail. The photochromic reaction of diarylethene 1o is shown in Scheme 1.
Scheme 1. Photoisomerization of diarylethene 1o
Advanced Materials Research Vol. 1003 (2014) pp 23-26
© (2014) Trans Tech Publications, Switzerland
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![Experiments
Synthsis of diarylethene 1o. Diarylethene 1o,
1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)perfluorocyclopentene, was
prepared based on the method described in Scheme 2. It was synthesized according to the similar
procedure of Pu et al. [11]. First, the compound 2-methylbenzothiophene 3 were obtained by alkylate
reaction. Then to a stirred solution of 3 in THF, Br2 was added dropwised at room temperature gave
compound 4. Meanwhile, 1,5-dimethyl-1H-pyrrole-2-carbonitrile 5 was slowly added Br2/acetic acid
mixture solution to give 4-bromo-1,5-dimethyl-2-pyrrolecarbonitrile 6. Compound 7 was obtained by
lithiated and coupled with octafluorocyclopentene. Finally compound 4 was further lithiated and then
coupled with compound 7 to give the product diarylethene 1o. After extracting with ethyl acetate and
evaporation in vacuum, the residue was purified by column chromatography on silica gel (petroleum
ether/ethyl acetate = 3:1) to obtain the target compound 1o. The structure of compound 1o was
confirmed by 1
H NMR spectroscopy. NMR spectra were recorded on Bruker AV400 (400 MHz)
spectrometer with CDCl3 as the solvent and tetramethylsilane as an internal standard.1
H NMR (400
MHz, CDCl3, TMS): δ 1.75 (s, 3H, -CH3), 2.30 (s, 3H, -CH3), 3.51 (s, 3H, -CH3), 6.77 (s, 1H,
pyrrole-H), 7.30-7.36 (m, 2H, benzene-H), 7.48 (d, 1H, J = 8.0 Hz, benzene-H), 7.74-7.77 (m, 1H,
benzene-H).
Preparation of PMMA Film. 100 mg of PMMA was first dissolved in 1 mL chloroform, which was
stirred ultrasonically to make it homogeneous. Samples were obtained by dissolving ultrasonically 10
mg of compounds 1 with 1 mL of the PMMA solution, respectively, and the solution was spin-coated
on a glass substrate with a spin rotation speed of 1500 rpm.
Scheme 2. Synthesis of diarylethene 1o
Results and Discussion
Photochromism of the diarylethene 1o. The changes in the absorption spectra of diarylethene 1o,
which were induced by photoirradiation at room temperature in hexane (2.0 × 10-5
mol/L) are shown
in Fig.1. Upon irradiation with 297 nm UV light, the colorless solution of 1o turned to voilet due to
the appearance of a new broad absorption band at λ = 547 nm assigned to the formation of the
closed-ring isomer 1c. Then, the voilet colored solution reverted to colorless upon irradiation with
visible light (λ > 500 nm), indicating that 1c returned to the initial state 1o, and a clear isosbestic point
was observed at 248 nm.
Similarly, the photochromism of diarylethene 1o in the PMMA amorphous film is shown in Fig.
1B. In PMMA film, upon irradiation 297 nm UV light, the color of 1o/PMMA film changed from
colorless to voilet due to the formation of the closed-ring isomer 1c, accompanied by a new broad
absorption band at 572 nm appeared. Then, upon irradiation of appropriate visible light (λ > 500 nm),
the colored PMMA film can back to colorless. From the above description, we can easily get a
conclusion that both open-ring isomer and closed-ring isomer of this diarylethene were stable in
solution at room temperature in darkness.
24 Advanced Research on Material Engineering, Electrical Engineering and
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![300 400 500 600
0.00
0.25
0.50
0.75
Absorbance
Wavelength/nm
Vis
UV
Vis
UV
Vis UV
300 400 500 600 700
0.0
0.5
1.0
1.5
Absorbance
Wavelength/nm
Vis
UV
Vis UV
Fig. 1 Absorption spectra upon alternating irradiation with UV-Vis light of the compound 1o in
hexane (2.0 × 10-5
mol/L).
Photochromic reaction kinetics in hexane solution. The photochromic cyclization and
cycloreversion kinetics of this diarylethene in hexane were determined by UV-Vis spectra upon
alternating irradiation with appropriate wavelength UV and visible light at room temperature. The
cyclization and cycloreversion curves of compound 1o were shown in Fig.2 (A), respectively. It can
be seen that the relationships between the absorbance and exposal time have good linearity upon
irradiation with 297 nm UV light. It is suggesting that the cyclization processes of compound 1o
belong to the zeroth order reactio when open-ring isomers changed to closed-ring isomers. At the
same time, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also
behave perfect linearity, as shown in Fig.2 (B), indicating that the cycloreversion process belong to
the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3
) of diarylethene 1c can
be easily obtained in solution, respectively.
0 8 16 24 32 40
0.01
0.02
0.03
0.04
0.05
0.06
Absorbance
Time/s
A
Y=A+B*X
A=0.0058
B=0.0013
R=0.9991
0 8 16 24 32 40
1.40
1.75
2.10
2.45
2.80
-log(Abs)
Time/s
B
Y=A+B*X
A=1.090
B=0.039
R=0.991
Fig. 2 The cyclization (A) and cycloreversion (B) kinetics of compound 1o in hexane.
Polarization Recording Properties. With a He-Ne laser (wavelength: 650 nm, 105 mW) in the
experimental setup, the evaluation of potential of photochromic diarylethene as a polarization
medium by recording and reading in a real-time operation was investigated. Using diarylethene
1/PMMA film as recording medium, the polarization patterns were recorded and read on the film
under the microscope as shown in Fig. 3. The result indicated that the new photochromic diarylethene
can be applied in high capacity optical storage [12].
Fig. 3 Experimental setup for writing and reading polarization spot patterns.
Advanced Materials Research Vol. 1003 25](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-38-320.jpg)
![Summary
A novel unsymmetrical diarylethene was synthesized to investigate its photochromism, kinetic and
fluorescence. Diarylethene 1o exhibited photochromism in hexane solution. The present results are
useful for the design of efficient photoactive and excellent characteristic diarylethene compounds.
Furthermore, the compound also functioned as a fluorescence switch.
Acknowledgment
The authors are grateful for the financial support from the National Natural Science Foundation of
China (21363009).
References
[1] W. Feng, K. Huang and M.X. Wang: Chin. Phys. Vol. 14 (2005), p. 306
[2] G. Berkovic, V. Krongauz and V. Weiss: Chem. Rev. Vol. 100 (2000), p. 1741
[3] Y.C. Liang, A.S. Dvornikov and P.M. Rentzepis: Macromolecules Vol. 35 (2002), p. 9377
[4] J. Yin, X. Cao, F. Yu, G.A. and S.H. Liu: Tetrahedron Lett. Vol. 49 (2008), p. 1582
[5] G. M. Tsivgoulis and J.M. Lehn: Angew. Chem. Int. Ed. Vol. 34 (1995), p. 1119
[6] M. Iire: Chem. Rev. Vol. 100 (2000), p. 1685
[7] H. Tian and S. J.Yang: Chem. Soc. Rev. Vol. 33 (2004), p. 85
[8] K. Higashiguchi, K. Matsuda, N. Tanifuji and M. Irie: J. Am. Chem. Soc. Vol. 127 (2005), p.
8922
[9] M Irie, O Miyatake, K Uchida and T Eriguchi: J. Am. Chem. Soc. Vol. 116 (1994), p. 9894
[10]K Uchida, T Ishikawa, M Takeshita and Irie M: Tetrahedron Vol. 54 (1998), p. 6627
[11]S.Z. Pu, G. Liu, L. Shen, and J.K. Xu: Organic Letters Vol. 9 (2007), p. 2139
[12]S.Z. Pu, H.H. Tang, B. Chen, J.K. Xu, W.H. Huang: Mater. Lett. Vol. 60 (2006), p. 3553
26 Advanced Research on Material Engineering, Electrical Engineering and
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![Research on Photochromic Materials with Synthesis and Properties of
1-(3,5-Dimethyl-4-isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]
perfluorocyclopentene
Guanming Liao, Dandan Xue, Chunhong Zheng* and Shouzhi Pu
Jiangxi Key Lab of Organic Chemistry, Jiangxi Science and Technology Normal University,
Nanchang 330013, China
zch722108@126.com
Keywords: Diarylethene; Photochromism; Isoxazole moiety; Fluorescence; Kinetic
Abstract. An asymmetrical photochromic diarylethene
1-(3,5-Dimethyl-4-isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene(1o)
was synthesized and its photochromic properties were investigated. Upon irradiation with 297 nm UV
light, 1o exhibited photochromism in hexane solution. The kinetic experiments showed that the
cyclization and cycloreversion processes were zeroth and first order reaction, respectively. Moreover,
diarylethene 1o also exhibited obviously fluorescence switches along with the photochromism.
Introduction
Photochromic materials have attracted a great deal of interest due to their potential application in
optical memories and switching devices [1,2]. Up to date, many types of photochromic compounds
have been reported. Among them, diarylethenes are one of the most promising candidates for
photoelectronic applications owing to their excellent thermal stability and fatigue resistance [3].
Perfluorodiarylethenes are well known as one of the most popular class of photochromic
diarylethenes [1]. Their photochromic properties depend on several factors, such as conformation of
the open-ring isomer [4], nature of heteroarylmoieties [1], and electronic properties of substitutes [5].
Particularly, the nature of heteroaryl moieties mainly dictates the properties of photochromic systems.
Upon recent reports [6-8],the isoxazole moiety induced some new features differing from
diarylethenes with other heteroaryl moieties reported.
As described above, herein, a novel unsymmetrical diarylethene1-(3,5-Dimethyl-4-
isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene (1o) was designed and
synthesized. Diarylethene 1o showed notable photochromism in hexane solution. The schematic
illustration of photochromism is shown in Scheme 1.
Scheme 1. Photochromism of diarylethene 1o.
Advanced Materials Research Vol. 1003 (2014) pp 27-30
© (2014) Trans Tech Publications, Switzerland
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![Experiments
Synthesis of diarylethene 1o. The synthesis route for diarylethene 1o is shown in Scheme 2.
According to the similar procedure [9], diarylethene 1o was synthesized visible as a light yellow with
a 56% yield. 1
H NMR (400 MHz, CDCl3,): δ 1.36 (t, 3H,-CH3), 1.95 (d, 6H, J = 8.0 Hz,-CH3), 3.84 (s,
3H, -CH3), 3.96–3.98 (m, 2H, -CH2), 6.83 (d, 2H, J = 8.0 Hz, benzene-H), 7.02 (s, 1H, thiophene-H),
7.36 (d, 2H, J = 8.0 Hz, benzene-H).
Scheme 2. Synthetic route for the diarylethene 1o.
Results and discussion
Photochromism of diarylethene 1o. The photoisomerization of ring-open isomer 1o and ring-closed
isomer 1c with UV/vis light irradiation was illustrated in Scheme 1.The absorption bands of 1o in
hexane (2.0 × 10-5
mol L-1
) appeared at 286 nm (2.3 × 104
L mol-1
cm-1
). Upon irradiation with 297 nm
light, the colorless solution of 1o was converted into a purple solution of 1c with an absorption band at
533 nm, and 1c could be bleached completely back to 1o with visible light ( λ > 510 nm), resulted in
the color change of the solution from purple to colorless. As shown in Fig. 1, it showed the typical
absorption spectra changes of diarylethene derivatives in solution and it could also be seen clearly that
an isosbestic point appeared in the absorption spectra changes of photocyclization, indicating only
two isomers existed when 1o underwent the photoisomerization reaction.
300 400 500 600 700
0.0
0.1
0.2
0.3
0.4
Absorbance
Wavelength/nm
Vis
UV
Vis
UV
Fig. 1. Absorption spectral and color change of 1o by photoirradiation in hexane (2.0 × 10-5
mol L-1
).
Photochromic reaction kinetics in hexane solution. The photochromic cyclization/cycloreversion
kinetics of 1o in hexane were determined by UV-Vis spectra upon alternating irradiation with UV and
appropriate wavelength visible light at room temperature. The cyclization and cycloreversion curves
of 1o were shown in Fig. 2. It can be seen that the relationships between the absorbance and exposal
time have good linearity upon irradiation with 297 nm UV light. It is demonstrating that the
cyclization processes of 1o belong to the zeroth order reaction when open-ring isomer changed to
closed-ring isomer. The slope of every line in Figs. 2(A) and 2(B) represents the reaction rate constant
(k) of diarylethene 1o in hexane. So all k of cyclization (ko-c, 10-3
) / cycloreversion (kc-o, 10-2
) process
of diarylethene 1o can be easily obtained, which are 1.40 mol L-1
s-1
and 7.80 s-1
in solution,
respectively. As shown in Fig. 2(B), during the cycloreversion of 1c, the relationship between
–log(Abs) and exposal time also behave perfect linearity, indicating that the cycloreversion process
belong to the first order reaction.
28 Advanced Research on Material Engineering, Electrical Engineering and
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![Fluorescence of diarylethene 1o. Fig. 3(A) shows the concentration dependence of fluorescence
emission spectra of 1o in hexane at room temperature, and the breadths of excitation and emission slit
were selected 5.0 nm and 5.0 nm, respectively. When the concentration of 1o in hexane increased
from 1.0 × 10-6
mol L-1
to 5.0 × 10-4
mol L-1
, the maximum emission arose from 451 to 453 nm when
excited at 299 nm and the fluorescence intensity increased with increasing concentration, especially,
when the concentration increased from 2.0 × 10-5
mol L-1
to 5.0 × 10-5
mol L-1
, the relative
fluorescence intensity increased remarkably, but when the concentration increased enough high, the
fluorescence intensity decreased rapidly. This self-quench phenomenon maybe resulted from the
formation of excimers and of exciplexes in high concentration solutions so that deactivation effect
can occur during the excited-state lifetime [10].
0 8 16 24 32 40
0.000
0.012
0.024
0.036
0.048
0.060
Absorbance
Time (s)
Y = 0.00618 + 0.00143 * X
R=0.99482
(A)
0 5 10 15 20 25
0.8
1.2
1.6
2.0
2.4
2.8
-log(Abs)
Time(s)
Y = 0.73704 + 0.07819 * X
R=0.99168
(B)
Fig. 2. The kinetics of diarylethene 1o in hexane: (A) cyclization; (B) cycloreversion.
The fluorescence emission spectra of diarylethene 1o in hexane (2.0 × 10-5
mol L-1
) was evaluated at
room temperature, and the result is shown in Fig. 3(B).The emission peak of 1o in hexane was
observed at 453 nm when excited at 299 nm. Typically, the fluorescence of diarylethene could be
reversibly modulated by photoirradiation during the process of photoisomerization [11-12]. Upon
irradiation with 297 nm light, the emission intensity of 1o was notably decreased in hexane solution
due to the formation of the weak fluorescent closed-ring isomer 1c. The back irradiation by
appropriate visible light regenerated the open-ring isomer 1o and recovered the original emission
intensity. As shown in Fig. 3, the emission intensity of 1o was quenched to ca. 73% in hexane in the
photostationary state. That is to say, the fluorescent modulation efficiency of 1o was 27% in hexane.
400 450 500 550
0
100
200
300
400
1x10-6 mol L-1
2x10-6 mol L-1
5x10-6 mol L-1
1x10-5 mol L-1
2x10-5 mol L-1
5x10-5 mol L-1
1x10-4 mol L-1
2x10-4 mol L-1
5x10-4 mol L-1
Emission
Intensity
(a.u.)
Wavelength (nm)
(A)
400 450 500 550
0
150
300
450
Emission
Intensity
(a.u.)
Wavelength (nm)
Vis
UV
(B)
Fig.3. (A) Fluorescence spectra of diarylethenke 1o in various concentrations in hexane excited at 299
nm at room temperature.(B)Emission intensity changes of diarylethene 1o upon irradiation with 297
nm UV light at room temperature in hexane (5.0 × 10-5
mol L-1
).
Summary
In summary, a novel diarylethene with isoxazole moiety has been synthesized. It showed good
photochromic behavior in hexane solution. Our experimental results showed that the cyclization
process of 1o belongs to the zeroth order reaction and the cycloreversion process belongs to the first
Advanced Materials Research Vol. 1003 29](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-42-320.jpg)
![order reaction, respectively. The fluorescence of the diarylethene 1o could also be reversibly
modulated by photoirradiation.
Acknowledgement
The authors are grateful for the financial support from the National Natural Science Foundation of
China (21362013, 51373072).
References
[1] M. Irie: Chem. Rev. Vol. 100 (2000), p. 1685
[2] H.H. Liu and Y. Chen: Dyes Pigm. Vol. 89 (2011), p. 212
[3] M. Morimoto, S. Kobatake and M. Irie: J. Am. Chem. Soc. Vol. 125 (2003), p. 11080
[4] M. Irie, O. Miyatake, K. Uchida and T. Eriguchi: J. Am. Chem. Soc. Vol. 116 (1994), p. 9894
[5] S.Z. Pu, C.H. Zheng, Z.G. Le, G. Liu and C.B. Fan: Tetrahedron. Vol. 64 (2008), p. 2576
[6] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron.Vol. 67 (2011), p. 1447
[7] G. Liu, M. Liu, S.Z. Pu, C.B. Fan and S.Q. Cui: Tetrahedron.Vol. 68 (2012), p. 2267
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[9] S.Z. Pu, G. Liu and J.K. Xu: Org. Lett. Vol. 9 (2007), p. 2139
[10]T. Fukaminato, T. Kawai, S. Kobatake and M. Irie: J. Phys. Chem. B. Vol. 107 (2003), p. 8372
[11]H. Tian, B.Z. Chen, H.Y. Tu and K.Müllen: Adv. Mater. Vol. 14 (2002), p. 918
[12]S.Z. Xiao, T. Yi, Y.F. Zhou, Q. Zhao, F.Y. Li and C.H. Huang: Tetrahedron. Vol. 62 (2006), p.
10072
30 Advanced Research on Material Engineering, Electrical Engineering and
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![Synthesis and Properties Study of
1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thieny
l]perfluorocyclopentene
Jingjing Liu, Hongjing Jia and Shouzhi Pu*
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University
Nanchang 330013, P.R.China
pushouzhi@tsinghua.org.cn
Keywords: Diarylethene, Photochromism, Pyrimidine, Fluorescence.
Abstract. A novel photochromic diarylethene bearing a pyrimidine moiety,
1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thienyl]perfluorocyclopentene
has been synthesized. Its properties, including photochromic behavior and fluorescent properties,
have been investigated. The compound exhibited remarkable photochromism, changing from
colorless to red after irradiation with UV light in solution. The fluorescence had a remarkable initial
increase with subsequent dramatic decrease with increasing concentration. The results indicated that
the pyrimidine moiety played a very important role during the process of photoisomerization
reactions.
Introduction
Photochromic diarylethenes undergo reversible photoisomerization between two isomers with
different absorption spectra upon irradiation with light of appropriate wavelength [1]. Photochromic
molecules have been attracted much attention from both fundamental as well as practical points of
view because of their potential applications for optical devices, such as optical memories and
switches [2-4]. Among the various types of photochromic compounds, diarylethenes are regarded as
the most promising candidates, because diarylethene derivatives have excellent thermal stability of
the respective isomers, notable fatigue resistance, rapid response, and high reactivity in solid state.
Diarylethene with heterocyclic aryl rings are the most promising candidates for photoelectronic
applications among various types of photochromic compounds [5-7].
In the past several decades, numerous studies have focused on molecular design, especially the
synthesis of symmetrical and asymmetrical frameworks in diarylethenes with different heteroaryl
units. For example, the diarylethenes having two thiophenes [8], furans [9] and thiazoles [10-12]
exhibit excellent thermal stability, and the ones with two indoles, pyrrols, and benzenes are
thermally unstable [12,13]. Nevertheless, the hexatriene backbones necessary for the versatility of
the diarylethenes reported so far have been mostly limited to the five-membered aryl rings. Up to
date, the reports about diarylethenes with six-membered pyrimidine rings are still very rare. In this
work, we synthesized a new diarylethene bearing a pyrimidine moiety, namely
1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thienyl]perfluorocyclopentene
(1o). Its photochromic reactivity and fluorescence were investigated in detail. The photochromic
reaction of diarylethene 1 is shown in Scheme 1.
F
F
F F
F
F
S
F
F
F F
F
F
S
UV
Vis
1c
N
N
O
O
N
N
O
O
1o
Scheme 1. Photochromism of diarylethene 1.
Advanced Materials Research Vol. 1003 (2014) pp 31-34
© (2014) Trans Tech Publications, Switzerland
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![decreased dramatically upon irradiation with 297 nm light, with the photochromism from open-ring
isomer to closed-ring isomer. The emission intensity of diarylethene 1c in a photostationary state was
quenched to ca. 39.9% in hexane and ca. 84.1% in PMMA film. The cyclization reaction which is
not complete and the existence of parallel conformations may be the main cause for the moderate
change in fluorescence induced by photoirradiation. The reversible changes of the emission intensity
of diarylethene 1 are useful for application as the fluorescence switches [14,15].
Figure 2 Fluorescence spectral changes of compound 1 in hexane (1.0 × 10-4
mol/L) (A) and in
PMMA (10%, w/w) (B) with 297 nm UV light.
The concentration dependence on the fluorescence spectrum of diarylethene 1o was measured in
hexane at room temperature, as shown in Figure. 3. When the concentration of diarylethene 1o in
hexane was increased from 1.0 × 10-6
mol/L to 1.0 × 10-4
mol/L, the maximum emission almost
arose at 434 nm when excited at 345 nm, and the relative fluorescence intensity increased
dramatically. However, when the concentration increased from 1.0 × 10-4
to 5.0 × 10-4
mol/L, the
relative fluorescence intensity decreased remarkably. The hexane solution showed very weak
fluorescence when the concentration was increased to 5.0 × 10-4
mol/L. The results showed that the
fluorescence of the compound was remarkably concentration dependent. The results also
demonstrated that molecular aggregation and the fluorescence quenching may occur when the
concentration increases [16].
Figure 3. Fluorescence of diarylethene 1o in various concentrations in hexane excited at 345 nm.
Summary
An unsymmetrical diarylethene with a pyrimidine unit was synthesized to investigate its
photochromism and fluorescence properties. The results showed that diarylethene 1o showed
excellent photochromism in solution. In addition, the diarylethene 1o also exhibited relatively
strong fluorescence in hexane solvent and in PMMA film. Its fluorescence had a remarkable initial
increase with subsequent dramatic decrease with increasing concentration.
Advanced Materials Research Vol. 1003 33](https://image.slidesharecdn.com/2383072-250604232713-4204d8f5/85/Advanced-Research-On-Material-Engineering-Electrical-Engineering-And-Applied-Technology-Ii-Helen-Zhang-46-320.jpg)
![Acknowledgment
The authors are grateful for the financial support from the National Natural Science Foundation of
China (21362013, 51373072).
References
[1] S. Kobatake and M. Irie: Chem. Lett. Vol. 32 (2003), p. 1078
[2] Y. Chen, C.M. Wang, M.G. Fan, B.L. Yao and N. Menke: Opt. Mater. Vol. 26 (2005), p. 75
[3] T. Fukaminato, T. Sasaki, T. Kawai, N. Tamai and M. Irie: J. Am. Chem. Soc. Vol. 126 (2004),
p.14843
[4] S.Z. Pu, F.S. Zhang, J.K. Xu, L. Shen, Q. Xiao and B. Chen: Mater. Lett. Vol. 60 (2006), p. 485
[5] M. Irie: Chem. Rev. Vol. 100 (2000), p. 1685
[6] K. Matsuda and M. Irie: J. Photoch. Photobiol. C. Vol. 5 (2004), p. 169
[7] M. Morimoto and M. Irie: Chem. Commun. Vol. 36 (2006), p. 3895
[8] H. Tian and S.J. Yang: Chem. Soc. Rev. Vol. 33 (2004), p. 85
[9] X.D. Deng and L.S. Liebeskind: J. Am. Chem. Soc. Vol. 123 (2001), p. 7703
[10] K. Uchida, T. shikawa, M. Takeshita and M. Irie: Tetrahedron Vol. 54 (1998), p. 6627
[11] S. Takami and M. Irie: Tetrahedron Vol. 60 (2004), p. 6155
[12] S.Z. Pu, H. Li, G. Liu and W.J. Liu: Tetrahedron Lett. Vol. 5 (2010), p. 3575
[13] K. Uchida, T. Matsuoka, K. Sayo, M. Iwamoto, S. Hayashi and M. Irie: Chem. Lett. Vol. 8
(1999), p. 835
[14] B. Chen, M. Wang, Y. Wu and H. Tian: Chem. Commun. Vol. 21 (2002), p. 1060
[15] H. Tian, B.Z. Chen, H.Y. Tu and K. Müllen: Adv. Mater. Vol. 17 (2002), p. 918
[16]T. Fukaminato, T. Kawai, S. Kobatake and M. Irie: J. Phys. Chem. B. Vol. 107 (2003), p. 8372
34 Advanced Research on Material Engineering, Electrical Engineering and
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![Research on Photochromic Materials with Synthesis and Application of
1-(2-methyl-3-benzothienyl)-2-[2-methyl-(5-ethynyl)
trimethylsilane-3-thienyl] Perfluorocyclopentene
Lele Ma, Hongyan Xu and Gang Liu*
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University,
Nanchang 330013, P.R.China
liugang0926@163.com
Keywords: Photochromism; Fluorescence; Kinetics; Diarylethene.
Abstract. A new unsymmetrical photochromic diarylethene compound,
1-(2-methyl-3-benzothienyl)-2- (2-methyl- (5-ethynyl)trimethylsilane-3-thienyl)
perfluorocyclopentene (1o) has been synthesized, and its optoelectronic properties, such as
photochromism and the fluorescence spectra of diarylethene 1o in hexane solution was investigated.
The results showed that this compound exhibited reversible photochromism in solution. The
maxima absorption of compound closed-ring isomer 1c are 538 nm. Its fluorescence intensity
decreased along with the photochromism from open-ring isomers to closed-ring isomers upon
irradiation with 297 nm UV light.
Introduction
Photochromic materials have been extensively investigated because of their potential application to
photonic devices, such as high-density optical recording materials and photoswitches [1-3] and
full-color display devices [4,5]. During the past decades, the majority of the study work reported
has been devoted to the development of these molecules and investigative studies of their
fundamental properties. In those literatures, diarylethene derivatives with heterocyclic aryl rings are
the most promising organic photochromic compounds for photoelectronic applications because of
the excellent thermal stability of both of the two isomers, fatigue resistant character, rapid response
and high reactivity in solid state [6,7]. Recently, we have been reported some new classes of
photochromic diarylethene derivatives [8-10].
In the present study, we designed a red photochromic diarylethene compound,
1-(2-methyl-3-benzothienyl)-2-(2-methyl-(5-ethynyl)trimethylsilane-3-thienyl)
perfluorocyclopentene (1o). The photochromic reaction of diarylethene 1o is shown in Scheme 1.
Scheme 1. Photochromism of diarylethenes 1
Experiments.
Synthesis of diarylethene 1o. The synthetic route for the diarylethene 1o was described in
according to the method described in Scheme 2. The structure of compound 1o was confirmed by
1
H NMR. NMR spectra were recorded on Bruker AV400 (400 MHz) spectrometer with CDCl3 as
the solvent and tetramethylsilane as an internal standard. 1
H NMR (400 MHz, CDCl3), δ (ppm):
0.15 (s, 9H), 1.73 (s, 3H), 2.18 (s, 3H), 7.12 (s, 1H),7.22-7.27 (m, 2H), 7.45 (d, 1H, J = 8.0Hz),
7.63 (d, 1H, J = 8.0Hz).
Advanced Materials Research Vol. 1003 (2014) pp 35-38
© (2014) Trans Tech Publications, Switzerland
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![Scheme 2. Synthetic route to diarylethene 1o
Results and Discussion
Photochromism in solution.
The changes of diarylethene 1o in the absorption spectra induced by photo-irradiation at room
temperature in hexane solution are shown in Fig. 1. The absorption show spectral changes of
diarylethene 1o in hexane(Fig. 1A) (2.0 × 10-5
mol/L) and in PMMA film(Fig. 1B) (10% w/w) by
photoirradiation, respectively. Upon irradiation with 297 nm light, the color of the solution turned
red, in which the absorption maximum was observed at 538 nm. Reversely, the red solution turned
colorless by irradiation with visible light (λ > 500 nm), indicating that 1c returned to the initial state
1o and a clear isosbestic point was observed at 259 nm. The significant difference in absorption
bands of the closed-ring isomer compared to its open-ring isomer is mainly due to the increase in π
conjugation, which dramatically changes the electronic structure as a whole in such a way that new
electronic transitions are observed in the visible region [11,12].
Fig.1 Absorption spectra changes of 1o in hexane (A) and in PMMA (B)
Photochromic Reaction Kinetics in Hexane Solution. The photochromic cyclization and
cycloreversion kinetics of this diarylethene in hexane were determined by UV-Vis spectra upon
alternating irradiation with appropriate wavelength UV and visible light at room temperature. The
cyclization and cycloreversion curves of 1o were shown in Fig. 2(A) and Fig. 2(B), respectively. It
can be seen that the relationships between the absorbance and exposal time have good linearity
upon irradiation with 297 nm UV light. The slope of line in Fig. 2(A) and Fig. 2(B) represents the
reaction rate constant (k) of 1o in hexane. It is suggesting that the cyclization processes of
compound 1o belong to the zeroth order reaction when open-ring isomers changed to closed-ring
isomers. At the same time, during the cycloreversion of 1c, the relationship between –log(Abs) and
exposal time also behave perfect linearity, as shown in Fig. 2(B), indicating that the cycloreversion
process belong to the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3
) of
diarylethene 1c can be easily obtained in solution, respectively.
36 Advanced Research on Material Engineering, Electrical Engineering and
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![References
[1] Y. Chen, D. X. Zeng, N. Xie: J. Org. Chem. Vol. 70(2004), p. 5001
[2] T. Fukaminato, T. Sasaki, and M. Irie : J. Am. Chem. Soc, Vol.126, p.14843
[3] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu: Dyes and Pigments Vol. 90 (2011), p. 71
[4] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui: Tetrahedron Vol. 67 (2011), p. 1438
[5] G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980
[6] K. Matsuda, M. Irie, J. Photochem. Photobiol. C: Photoch. Vol. 5 (2004), p.169.
[7] H. Tian: Angew. Chem. Int. Ed. Vol. 49 (2010), p.4710
[8] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu and T.S. Yang: Dyes and Pigments Vol. 90 (2011), p. 71
[9] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron Vol. 67 (2011), p. 1438
[10]G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980
[11]S.Z. Pu, C.H. Zheng, Z.G. Le, G. Liu and C.B. Fang: Tetrahedron Vol. 64 (2008), p. 2576
[12]Z. X. Li, L. Y. Liao, W. Sun, C. H. Xu, C. Zhang, C. J. Fang and C. H. Yan: J. Phys. Chem.
Vol. 112 (2008), p. 5190
38 Advanced Research on Material Engineering, Electrical Engineering and
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![Research on Photochromic Compounds with Efficient Synthesis and
Photochromic Properties of
1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]
perfluorocyclopentene
Junjie Song and Gang Liu*
Jiangxi Key Lab of Organic Chemistry, Jiangxi Science and Technology Normal University
Nanchang 330013, China
liugang0926@163.com
Keywords: Phenyl; Diarylethene; Photochromism; Fluorescence
Abstract. A novel isomeric photochromic diarylethene, 1-(2-methyl-5-phenyl-3-thienyl)-
2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]perfluorocyclopentene, was designed and synthesized. Its
fluorescent and photochromic properties were also studied in detail. The compound exhibited
excellent photochromism, changing from colorless to bule after irradiation with UV light both in
solution and in PMMA film. In addition, the fluorescence intensity of the photochromic diarylethene
1a declined remarkably, when irradiation with UV light.
Introduction
Photochromic compounds have been extensively designed and synthesized for their potential
applications in erasable optical memories, displays, and optical switches [1-3]. Thus, further creation
of optoelectronic and photo-optical devices based on photochromic molecular switches which
operate at both molecular and supramolecular levels have recently attracted many attentions [4].
Photochromic is referred to as a photoisomerization process between two isomers having different
absorption spectra [5]. Among the various types of photochromic compounds, diarylethenes are
regarded as the most promising candidates, because of diarylethene derivatives have excellent
thermal stability of the respective isomers, notable fatigue resistance, and rapid response, and high
reactivity in solid state, diarylethene with heterocyclic aryl rings are the most promising candidates
for photoelectronic applications among various types of photochromic compounds [6-8].
F
F
F F
F
F
S
S
F
F
F F
F
F
S S
UV
vis
1a 1b
Scheme 1. Photochromism of dithienylethene 1a.
Up to now, a large number of publications concerning about diarylethene derivatives with different
aryl moieties, such as thiazole [9,10,11], indole [12], benzofuran [13], crysothiophene [14], pyrrole
[15] and indene [16], etc, have been reported. Among these novle photochromic diarylethenes, there
are few examples of photochromic diarylethenes bearing phenanthrene rings. The results highly
encourage us to develop a new class of hybrid photochromic diarylethene derivatives bearing an
phenanthrene moiety. In this paper, we designed and synthesized a new diarylethene bearing
phenanthrene unit and fused ring units, namely 1-(2-methyl-5-phenyl-3-thienyl)
-2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]perfluorocyclopentene (1a). Its photochromic reactivity,
fluorescence were investigated in detail. The photochromic reaction of diarylethene 1a is shown in
Scheme 1.
Advanced Materials Research Vol. 1003 (2014) pp 39-42
© (2014) Trans Tech Publications, Switzerland
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![Experiments
The synthetic route for the diarylethene 1a is shown in Scheme 2. Suzuki coupling of the
bromobenzene derivative with a thiophene boronic acid 2 gave the compound 3. Under an argon gas
atmosphere, compound 4 was dissolved in THF and n-Butyl lithium hexane solution was added at
195 K. Stirring was continued for 30 min at this low temperature, octafluorocyclopentene was added
and the mixture was stirred for 2 h at this temperature. Then compound 5 was yield. Compound 1a
was prepared by reacting compound 3 with compound 5 in dry THF at 195 K. After extracting with
diethyl ether and evaporation in vacuo, the residue was purified by column chromatography on silica
gel to give 1a. The structures of diarylethenes 1a were confirmed by 1
H NMR (400 MHz, CDCl3,
TMS): δ 0.80-0.91 (m, 3H), 1.16-1.25 (m, 4H), 1.35-1.54 (m, 2H), 2.35-2.37 (t, 6H),2.54-2.67 (m,
2H) 7.01-7.18 (d, 2H), 7.21-7.24 (d, 1H), 7.26-7.43 (d, 2H), 7.46-7.52 (t, 2H), 7.71-7.74 (d, 4H)
F
F
F F
F
F
n-BuLi/THF
C5F8,
S
Br
S
Br
B(OH)2
Br
Pd(PPh3)4,Na2CO3,aq
n-BuLi/THF
195K
195K
1a
F
2 3
4 5
S
Br
S
F
F
F F
F
F
S
S
Scheme 2. Synthetic route for the compound 1a.
Results and Discussion
Photochromism of diarylethene. The unsymmetrical diarylethene 1a exhibits good photochromic
properties and can be toggled between its colorless ring-open and colored ring-closed forms by
alternate irradiation with appropriate wavelengths of light. The absorption spectral changes in hexane
are shown in Fig. 1. The open ring isomer has an absorption maximum at 280 which was arisen from
π→π* transition. Upon irradiation with 297 nm UV light, the colorless hexane solution of compound
1a turned blue, in which absorption maximum was observed at 571 nm. The blue color is due to the
formation of the closed ring isomer. When blue solution was irradiated with visible light (λ > 450
nm), the blue color could return back to colorless and its spectrum became the same as that of original
one, indicating compound 1a returned to the initial open ring isomer. The coloration/discoloration
cycle could be repeated more than 50 times and the photostationary spectrum was almost the same as
that of the colored isomer. This indicates a high conversion from the colorless to the colored isomers
by irradiation with 297 nm light.
In order to practical applications in optical devices for the future, it is extremely important that
photochromic materials can keep excellent photochromic in a polymer film, such as the PMMA film.
Dissolved ultrasonically 5 mg diarylethene sample and 50 mg PMMA into 0.5 mL chloroform, the
film was prepared by spin-coating method. In PMMA amorphous film, diarylethene 1a also showed
good photochromic (Fig. 1b) as similar to that in solution. Upon irradiation with 297 nm light, the
colorless diarylethene 1a /PMMA film turned blue for which the absorption maxima were observed at
584 nm, as the closed-ring isomer 1b was generated. The colored diarylethene /PMMA films can
revert to colorless upon irradiation with visible light (λ > 450 nm). The color changes of diarylethene
upon photoirradiation in hexane and in PMMA are also shown in Fig. 1a and Fig. 1b respectively. The
maximum absorption peaks of both the open-ring and the closed-ring isomers in PMMA film are
longer than those in hexane solution. The red shift phenomenon is consistent with those of the
majority of the reported diarylethenes [17].
40 Advanced Research on Material Engineering, Electrical Engineering and
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![Fig. 1 Absorption spectral and color changes of compound 1 in hexane (2.0 × 10-5
mol L-1
) (a) and in
PMMA film (10%, w/w) (b).
Fluorescent of diarylethene. Fluorescent properties can be useful not only in molecularscale
optoelectronics, but for digital photoswitching of fluorescence. In this work, the fluorescence
properties of the diarylethene both in solution and in PMMA film(10% w/w) were measured using a
Hitachi F-4600 spectrophotometer. The result showed that 1a exhibited good fluorescence both in
hexane solution and in PMMA film, and the emission peaks are 393 and 472 nm , respectively.
The fluorescence intensity of diarylethene 1a decreased dramatically along with the photochromism
from open-ring isomer to closed-ring isomer upon irradiation with 297 nm light. As shown in Figure
2, when irradiated by light of 297 nm, the photocyclization reaction was carried out and the
non-fluorescent closed-ring form of the compound were produced. The back irradiation by
appropriate wavelength visible light regenerated the open-ring forms of diarylethene 1a and
recovered the original emission spectra. The emission intensity of diarylethene 1a in a
photostationary state was quenched to ca. 15% in hexane and ca. 33% in PMMA film. The
incomplete cyclization reaction and the existence of parallel conformations may be the main cause for
the moderate change in fluorescence induced by photoirradiation. The reversible changes of the
emission intensity of diarylethene 1a are useful for application as the fluorescence switches [18,19].
Fig. 2 Fluorescence spectral changes of compound 1 in hexane(2.0 × 10-5
mol L-1
) (a) and in PMMA
(b) with 297 nm UV light.
Summary
In conclusion, a new diarylethene derivative, which is described here with good photochromic
properties both in solution and in PMMA amorphous film, has been synthesized. Furthermore, it has
also been demonstrated that both the open ring and closed ring isomers of the diarylethene
compounds exhibit strong fluorescence, and their maximum emission wavelengths were observed at
393 nm when excited at 318 nm. The results illustrated that the diarylethene 1a had attractive
properties for polarization holographic optical recording. Such diarylethene derivatives have been
expected to have wide application in optical data storage and retrieval, rewritable optical memory and
display, various sensors and switches, etc.
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Advanced Research On Material Engineering Electrical Engineering And Applied Technology Ii Helen Zhang
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- 6. Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II Edited by Helen Zhang M. Han X.J. Zhao
- 7. Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II Selected, peer reviewed papers from the 2014 2nd International Conference on Insulating Materials, Material Application and Electrical Engineering (MAEE 2014), July 26-27, 2014, Nanjing, China Edited by Helen Zhang, M. Han and X.J. Zhao
- 8. Copyright 2014 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of the contents of this publication may be reproduced or transmitted in any form or by any means without the written permission of the publisher. Trans Tech Publications Ltd Churerstrasse 20 CH-8808 Pfaffikon Switzerland http://www.ttp.net Volume 1003 of Advanced Materials Research ISSN print 1022-6680 ISSN cd 1022-6680 ISSN web 1662-8985 Full text available online at http://www.scientific.net Distributed worldwide by and in the Americas by Trans Tech Publications Ltd Trans Tech Publications Inc. Churerstrasse 20 PO Box 699, May Street CH-8808 Pfaffikon Enfield, NH 03748 Switzerland USA Phone: +1 (603) 632-7377 Fax: +41 (44) 922 10 33 Fax: +1 (603) 632-5611 e-mail: sales@ttp.net e-mail: sales-usa@ttp.net
- 9. Preface MAEE2014 is a comprehensive conference,and it is an integrated conference concentrating its focus upon Material Engineering, Electrical engineering and Applied Technology. In the proceeding, you can learn much more knowledge about Material Engineering, Electrical engineering and Applied Technology of researchers all around the world. The main role of the proceeding is to be used as an exchange pillar for researchers who are working in the mentioned field. In order to meet high standard of Advanced Material Research ,the organization committee has made their efforts to do the following things. Firstly, poor quality paper has been refused after reviewing course by anonymous referee experts. Secondly, periodically review meetings have been held around the reviewers about five times for exchanging reviewing suggestions. Finally, the conference organization had several preliminary sessions before the conference. Through efforts of different people and departments, the conference will be successful and fruitful. MAEE2014 is co-sponsored by ISER Association, Beijing Gireida Education Research Center and VIP-Information Conference Center,China. The goal of the conference is to provide researchers from environment science, material application and applied technology fields with a free exchanging forum to share the new ideas, new innovation and solutions with each other. In addition, the conference organizer will invite some famous keynote speaker to deliver their speech in the conference. All participants will have chance to discuss with the speakers face to face, which is very helpful for participants. During the organization course, we have got help from different people, different departments, different institutions. Here, we would like to show our first sincere thanks to Mr. Thomas Wohlbier,Anne and Trans Tech Publications for their kind and enthusiastic help and support for our conference. Secondly, the authors should be thanked too for their enthusiastic writing attitudes toward their papers. Thirdly, all members of program chairs, reviewers and program committees should also be appreciated for their hard work. In a word, it is the different team efforts that they make our conference be successful on July 26-27,2 014, Nanjing, China. We hope that all of participants can give us good suggestions to improve our working efficiency and service in the future. And we also hope to get your supporting all the way. Next year, In 2015, we look forward to seeing all of you at MAEE2015. June,2014 MAEE committee
- 10. Committee Honor Chairs Prof. Chen Bin, Beijing Normal University,China Prof. Hu Chen, Peking University,China Chunhua Tan, Beijing Normal University,China Helen Zhang, University of Munich,China Program Committee Chairs Xiong Huang, International Science& Education Researcher Association,China LiDing, International Science& Education Researcher Association,China Zhihua Xu, International Science& Education Researcher Association,China Organizing Chair ZongMing Tu, Beijing Gireida Education Co.Ltd,China Jijun Wang, Beijing Spon Technology Research Institution,China Quanxiang, Beijing Prophet Science and Education Research Center,China Publication Chair Zhihua Xu, International Science& Education Researcher Association,China Sally Wang, Beijing Normal University,China Committee Sally Wang, Beijing normal university,China LiLi, Dongguan University of Technology,China BingXiao, Anhui university,China Z. L. Wang, Wuhan university,China Moon Seho,Hoseo University,Korea Kongel Arearak,Suranaree University of Technology,Thailand Zhihua Xu, International Science& Education Researcher Association,China Xiangrong Jiang, Wuhan University of Technology,China LiHu, Linguistic and Linguidtic Education Association,China Moon Hyan,Sungkyunkwan University, Korea Guangwen, South China University of Technology,China Jack.H. Li, George Mason University, USA Marry. Y. Feng, University of Technology Sydney, Australia Li Hu, Wuhan University of Science and Technology, China, ZhongYan, Wuhan University of Science and Technology, China Haiquan Huang, Hubei University of Technology,China Xiao Bing, WUhan University, China Brown Wu, Sun Yat-Sen University, China Co-sponsored by International Science& Education Researcher Association, China Beijing Gireida Education Research Center VIP-Information Conference Center,China
- 11. Table of Contents Preface and Committee Chapter 1: Chemical Materials Research Kinetics on the Ultrasonic-Assisted Extraction of Polysaccharides from Limonium bicolor kunze (Bge.) X. Song, P. Zhao, Q.H. Meng, Z.S. Tang and C.L. Wang 3 Characterization and Photoluminescence of Sr2B2O5:Eu3+ , Na+ Red Phosphor L.L. Ying, S.S. Zheng, J.H. Zheng, L.H. Cai and C. Chen 7 Synthesis and Fluorescence Properties of a New Eu(III) Complexes with β-Diketone Ligand Y.N. Lu, X.Y. Zhao and X. Wang 11 Synthesis and Photochromism Studies of 1-(3,5-dimethyl-4-isoxazole)-2-[2-methyl-5- naphthyl-3-thienyl] perfluorocyclopentene X.R. Dong, R.J. Wang, G. Liu and S.Z. Pu 15 Research on Photochromic Materials with Synthesis and Properties of a New Unsymmetrical Diarylethene 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4- methylene-bromine)phenyl]-3-thienyl} Perfluorocyclopentene F. Duan and G. Liu 19 Research on Photochromic Compounds with Synthesis and Properties of a Novel Unsymmetrical Diarylethene with a Benzothiophene and a Pyrrole Group H.J. Jia, Y.L. Fu and C.B. Fan 23 Research on Photochromic Materials with Synthesis and Properties of 1-(3,5-Dimethyl-4- isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene G.M. Liao, D.D. Xue, C.H. Zheng and S.Z. Pu 27 Synthesis and Properties Study of 1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9- phenanthrene)-3-thienyl] perfluorocyclopentene J.J. Liu, H.J. Jia and S.Z. Pu 31 Research on Photochromic Materials with Synthesis and Application of 1-(2-methyl-3- benzothienyl)-2-[2-methyl-(5-ethynyl)trimethylsilane-3-thienyl] Perfluorocyclopentene L.L. Ma, H.Y. Xu and G. Liu 35 Research on Photochromic Compounds with Efficient Synthesis and Photochromic Properties of 1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-pentylphenyl)-3-thienyl] perfluorocyclopentene J.J. Song and G. Liu 39 Research on Photochromic Compounds with Efficient Synthesis and Photochromic Properties of 1-(2-methyl-5-chlorine-3-thienyl)-2-[2-methyl -5-(4-chlorophenyl)-3-thienyl] Perfluorocyclopentene F.X. Sun, S.Q. Cui and S.Z. Pu 43 Synthesis, Photochromism and Fluorescent Switch of 1-(2-methyl-1-benzofuran-3-yl)-2-(2- methyl-5-(4-benzylamine)-3-thienyl)) perfluorocyclopentene Z.Y. Tian, S.Q. Cui and S.Z. Pu 47 Efficient Synthesis, Photochromism and Fluorescence Properties of a Novel Diarylethene Bearing a Fluorene S.J. Xia, X.R. Dong and G. Liu 51 Research on Photochromic Compounds with Synthesis and Photochromism of 1-(2-methyl- 3-benzofuryl)-2-{2-methyl-5-[4-formyloxyethyl (Rhodamine-B)] phenyl-3-thienyl} Perfluoroyclopentene D.D. Xue, G.M. Liao, C.H. Zheng and S.Z. Pu 55 Efficient Synthesis, Photochromism and Fluorescence Properties of a Novel Diarylethene Bearing a Naphthalene H.Y. Xu, L.L. Ma and S.Z. Pu 59 Synthesis and Properties of 1-[2,5-dimethyl-3-thienyl]-2-[2-methyl-5-(4-pentylphenyl)-3- thienyl] perfluorocyclopentene C.C. Zhang, S.S. Wei and S.Z. Pu 63
- 12. b Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II Chapter 2: Materials Science, Processing and Application Hydrophobic Modification on Surface of Silicone Rubber by Tetrafluoromethane Radio Frequency Inductively Coupled Plasma S.H. Gao and L.H. Gao 69 Study on Corrosion Behavior of Copper-Clad Steel Bars with Unclad Two-End Faces for Grounding Grids in the Coastal Soil Y.P. Shao, A.J. Yan, X.H. Zhang, Y.N. Wang and Q.Q. Liao 74 Simulation and Test for the Lightning Damage of the Glass Fiber Composites X.N. Chen, J.L. Zhao, Y.S. Zhang and B. Zhang 78 Research on Biological Materials with Effect of Constant Magnetic Field Intervention on Bone Growth and Development in Rabbits L. Lv and J.H. Yang 85 Development of Combined Monitoring System of MOA Insulating Material and CT (Casing Tube) Insulating Material N. Su, Q.L. Xu and C.Y. Gui 91 Study on the Properties of Multi-Extruded Recycled PE and PP L. Sun, X.Y. Zhao and Z.Y. Sun 96 Research on Carbon Materials with Synthesis and Characterization of Graphene-Based P.P. Li and B.X. Deng 100 Influence of Original Surface Roughness on Ultrasonic Deep Rolling Effects D. Pei, F.G. Deng, J.W. Hu, Z.J. Yang and L. Li 105 The Application of Tissue Engineering and Biological Materials on Exercise-Induced Meniscus Injury L. Zhang, Z.Q. Zhao, X.L. Miao and H.M. Zhuang 109 Numerical Study on Bending Behavior of Copper Alloy Thin Plate by Single Pulse Laser S.Q. Jiang, A.H. Liu, X.T. Wang, J.H. Wu and B.K. Li 113 Chapter 3: Power Systems and Electronics Research on Electrical Engineering with a Multi Energy-Type Coordinated Micro-Grid Day-Ahead Scheduling Strategy Based on IPSO Algorithm C.J. Ma and J.X. Lu 119 Research on Electrical Engineering with a New Fault Location Method of Double Terminal Based on HHT J.X. Lu and C.J. Ma 124 Design and Implementation of Frequency Measuring Circuit Based on Countdown Counter L.X. Xu and X. Shi 130 Condition Assessment for Power Transformer Based on Improved Evidence Combination Rule F. Miao, J.W. Ren and J.J. Wei 135 Research on Foronline Short-Term Risk Assessment of Power System with Fast and Accurate Analysis Method Based on State Space Division H.N. Li and J.H. Zhang 140 Influence of Wind Farm with PMSG Type on Small Signal Stability of Power System J.C. Zhang, X.R. Zhu and W. Zhao 148 Reactive Power and Voltage Coordinated Control Research of Wind Farm Adopting Doubly-Fed Induction Generators W. Zhao, X.R. Zhu and J.C. Zhang 152 Phase D-Value Digital Measuring Algorithms Study and Design in Power System W.Y. Su and G. Li 156 Analysis of the Unexpected Opening of ABB Circuit-Breaker Opening under 30% Control Voltage Z.Q. Yu and X. Wang 160 Harmonic Computation and Analysis of Nonlinear Magnetic Field in the Ferromagnetic Core of the Transformer X.J. Zhao, X.L. Chen, C. Cui and Y.T. Zhong 165
- 13. Advanced Materials Research Vol. 1003 c Introduction and Study on Protective Relaying in Power System Y.L. Fan and Q.E. Li 169 Detection Method of Magnetically Controlled Reactor as Excitation Device C.Z. Wang 173 Zero Crossing Point Phase Detector Simulation Based on PROTEUS W.Y. Su and G. Li 177 Chapter 4: Detection, Control and Computational Methods, Algorithms Study on Well Logging Technology with Methods of Evaluating Gas Content of Coal-Bed Methane Reservoir H.J. Yang and H.P. Pan 183 The Improvement of Data Acquisition System in Computerized Well Logging Equipment G. Li, H.P. Pan and S.N. Fang 188 A Detection System of Impurity in Transparent Liquid B. Huang, P. Wang and S.L. Ma 193 Metrology Information System for Management and Field Scene Detection J.W. Qiao, Q.G. Liang and G.M. Tang 198 Research on Controlling and Management Measures with Engineering Technology in Freeway Construction Project H.P. Yin, G. Li and S. Li 203 Research on Embedded System with Implementation of a Moving Object Tracking Algorithm Based on Improved Meanshift on DM6437 Y.F. Liu, Q. Li, H. Fang and H.C. Xu 207 A Research on an Effective Method for Embedded Software Testing J.C. Bi, Q. Li, W.H. Dou and J.F. Xu 211 Design of a New Image Processing System Based on FPGA Q. Li, Y. Yang, Z.K. Li and J. Lu 216 Design and Implementation of an Intelligent Cleaning Robot Based on Fuzzy Control H.Y. Liu 221 Research on Applied-Information Technology with PM2.5 Generation and Evolution Model Based on BP Neural Network Y.H. Xie, X.W. Han and Q. Li 226 Research on Applied-Information Technology with Application of Data Mining in Analysis of Consumer Behavior F.L. Fan, X. Li, X.S. Yu and L. Wang 230 Applied Technology in "GNSS if Signal Acquisition System" and Software Receiver Design Y. Yang, C.L. Yang and Y.F. Liu 235 Data Processing and Applied Technology in the Algorithm and Cracking of NTLM-Hash - A Highly Proficient Parallel Computing Architecture J.C. Bi, C.G. Zhang, Y.F. Liu and W.H. Dou 239 An Algorithm for Testing the Unreachable Instruction of an Assembly Program in Software Coverage Testing J.C. Bi, Y.F. Liu, W.H. Dou and J.F. Xu 245 Design of Embedded Video Monitoring System Based on DM6437 H. Fang, A.H. Li and Y.F. Liu 249 Data Processing with an Innovation Self-Adaptive Denoising Amalgamation Algorithm J.Y. Hu, S.M. Hou and Y.F. Liu 254 The Research of NURBS Curve Interpolation Algorithm Based on Parabolic and the First- Order Taylor Expansion Interpolation Algorithm Z.Q. Zhang, W.J. Wang, J. Zhang, J. Zhao, L.Y. Sun, J.J. Li and L.L. Zhang 260 Guided Waves Propagating Analysis in Hollow Cone X.H. Yin and J.W. Qiao 264 Analysis of Environmental Materials with Correlation between PM2.5 and Other Indexes in AQI of Wuhan Y.H. Xie, X.W. Han, P. Sun and X.L. Zhang 269 Investigation into In-Vehicle Information Security Y. Huang, G.H. Qin, T. Liu, R. Zhao and X.D. Wang 273
- 14. d Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II Research on Permeability Upscaling Based on Numerical Rock Core and Geomechanics C. Niu, D.L. Li and D.T. Lu 279
- 15. CHAPTER 1: Chemical Materials Research
- 16. Kinetics on the ultrasonic-assisted extraction of polysaccharides from Limonium bicolor Kunze (Bge.) Xiao Song, Peng Zhao, Qing-hua Meng, Zhi-shu Tang, Chang-li Wang College of Pharmacy,Shaan Xi University of Chinese Medicine, Xian Yang 712046, China Zhaopeng65@sina.com Keywords: Limonium bicolor Kunze (Bge.); polysaccharide; ultrasonic; extraction; dynamics Abstract. To explore the kinetics parameters in the ultrasonic-assisted extraction from Limonium bicolor Kunze (Bge.) , the kinetic equation for polysaccharide ultrasonic extraction process was established with ball model. According to Fick’s second law of diffusion, extraction process was analysed. The results can provide the valuable theory basis for the technical design and further research of polysaccharide extraction process. Introduction Limonium bicolor Kunze(Bge.) grows and is widely cultivated in Shanxi, Shaanxi,Gansu provinces of China.The full plant is widely used for the treatment of bleeding,cancer nephritis and other weakness symptom as a traditional Chinese medicine[1].Polysaccharides, one of the main functional ingredients in the Limonium bicolor Kunze, has been shown to can signicantly inhibit the growth of hela cells in vitro[2]. Initially classical hot water extraction (HWE) of polysaccharides from Limonium bicolor Kunze (Bge.) has been carried out just to compare with microwave-assisted extraction (MAE). It should be noted that HWE is associated with long extraction time and high temperature. Recently, alternative extraction techniques such as ultrasonic assisted extraction (UAE) and membrane separation technology with lower temperature and enhanced yield had also been reported[3,4]. The extraction process, which is concerned with ultrasonic assisted extraction of the effective compounds from the Limonium bicolor Kunze (Bge.), is quite important and essential in polysaccharides production. The operating conditions, such as extraction temperature, time, power etc. considerably influence yields of the polysaccharides. However, to date, no investigation has been carried out on the extraction process of polysaccharides from Limonium bicolor Kunze (Bge.). Up to now, suitable values of the operating conditions have to be regulated only according to conventional experiences accumulated for centuries owing to lack of scientific methods.Thus the aim of this paper is to increase the ultrasonic assisted extraction rate of polysaccharides from Limonium bicolor Kunze (Bge.). and choose a suitable extraction reactor, the kinetics of ultrasonic assisted extraction polysaccharides from Limonium bicolor Kunze (Bge.) is probed. Methods Materials Limonium bicolor Kunze (Bge.).was purchased from Xi’an medicine produce market, then ground to pass through 60 mesh screen and dried at 80℃. Ethanol, phenol, sulfuric acid and ethyl ether were purchased from Xi’an Chemical Co.( Xi’an,China). All chemicals used in this study were analytical grade. Mathematical model The plant extraction process plays a very important role in plant production. The goal of the plant extraction process is to extract effective compounds from the herb. The real plant extraction process can be divided into five sub-processes on the whole, that is: (1)Diffusion of liquid through the film surrounding the particle to the surface of the solid; (2)Diffusion of solvent through the blanket of remainder to the surface of the un-reacted core; (3)Reaction of solvent with flavonoids at this reaction surface; (4)Diffusion of products through the remainder to the exterior surface of the solid; (5)Diffusion of products through the exterior surface into the liquid phase. The Advanced Materials Research Vol. 1003 (2014) pp 3-6 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.3
- 17. extraction rates of effective compounds, however, are dominated by the diffusion rates. So the herb extraction process model focuses on the diffusion process of the effective compounds, which first diffuse to the surface of the herb from the inside of the herb particle and then move to the bulk of the solution. A rigorous mass transfer model is presented in this paper by analyzing the diffusion process mechanically. Fick’s spherical coordinate equation resolution To study the diffusion phenomena following the ultrasonic-assisted process used in the production of the polysaccharides from Limonium bicolor Kunze (Bge.), the second Fick’s law written in spherical coordinates has been considered. ∂ ∂ + ∂ ∂ = ∂ ∂ r c r r c D t c s 2 2 2 (1) where Ds is the diffusion coefficient (Ds=D+Du, D is the diffusion coefficient with hot water extraction, Du is the diffusion coefficient with ultrasonic-assisted extraction), c is the mobile specie concentration, r is the spherical coordinate, and t is the time. If r c f ⋅ = ， so 2 2 r f D t f s ∂ ∂ = ∂ ∂ ( 0 , 0 = = f r ) (2) And R r = ， R r s out out r c S D V t C = ∂ ∂ − = ⋅ ∂ ∂ (3) Then ( ) ( ) [ ] { } ∑ ∞ = ∞ ∞ − = − − 1 2 2 0 / exp / 6 ) /( ) ( n st D R n C C C C π π (4) If n=1，so： ( ) ( ) [ ] 2 2 2 0 / exp / 6 ) /( ) ( R t D C C C C s π π − = − − ∞ ∞ (5) And ： ( ) ( ) [ ] ( ) [ ] 0 2 6 / ln / ln C C C kt C C C − + = − ∞ ∞ ∞ ∞ π , 2 2 / R D k s π = (6) So the total mass transfer equation can be deduced as above (5) and (6). In this work , Du＞＞ D, so we believe Ds≈Du. Polysaccharide extraction method 15 g Limonium bicolor Kunze (Bge.) (particle radius is about 3 mm) and 300 ml distilled water which had been heated up to 70℃ were added in the 500 mL bottle, then in every equal minutes, 0.1 mL sample was obtained from the extractionsystem to detcet the concentration of polysaccharides. The solution volume of each sample is 0.1mL and the whole extraction process take nine. The extraction system is changed after sampling, so the need to press (7) measured the concentration of polysaccharides amended: ( ) [ ] + − − = ∑ = 9 1 1 . 0 1 1 . 0 300 300 1 n i t n C C n C (7) where Cn is the n-th sample measured polysaccharide concentration correction value, µg / mL; Ci for the n samples the measured values of the polysaccharides concentration, µg / mL; n is the sample number of n = l, 2, ... 9. 4 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 18. Parameter estimation By varying the operating conditions (Table 1), the effects of power and time on the yields of polysaccharides are investigated (the ratio of water to raw material was 20). Table1 Concentration of polysaccharid at different power（mg/mL） extraction time/min Power /W 40 50 60 70 80 5 0.080 0.109 0.142 0.201 0.221 10 0.132 0.160 0.201 0.245 0.260 15 0.183 0.217 0.261 0.282 0.297 20 0.256 0.328 0.392 0.445 0.470 25 0.304 0.390 0.487 0.538 0.554 30 0.338 0.441 0.546 0.601 0.612 35 0.365 0.479 0.575 0.619 0.643 40 0.388 0.502 0.661 0.679 0.697 45 0.402 0.557 0.663 0.679 0.697 50 0.461 0.556 0.660 0.676 0.659 55 0.459 0.553 0.650 0.649 0.659 Table1 gives the results of the concentration of polysaccharides against the extraction time. It was found that the higher the power, the greater the extraction rate.In the extraction process, if the concentration of the polysaccharide extract in a long time remained unchanged, that has been to reach extraction equilibrium at this time. The concentration can be as a polysaccharide extracted from the equilibrium concentration（C∞）. The relation between the extractiontime and the concentration of the polysaccharide (ln[C∞/(C∞-C)]) can be good understood by the curves plotted in Fig. 1. Fig.1 Relationship between ln[C∞/（C∞-C）] and t at different power From Fig.1, the linear regression equation and the corresponding apparent rate constant can be obtained.As shown as in Table 2. Table2 Relationship between ln[C∞/（C∞-C）]and t at different temperature Power/W Linear equation R2 C∞ /mg·mL-1 k×10-4 /s-1 40 ln[C∞/（C∞-C）]=0.0428t- 0.088 0.9945 0.462 7.135 50 ln[C∞/（C∞-C）]= 0.052t-0.167 0.9783 0.557 9.1 60 ln[C∞/（C∞-C）]= 0.057t -0.186 0.9641 0.661 10.72 70 ln[C∞/（C∞-C）]= 0.0683t -0.253 0.9523 0.684 11.44 80 ln[C∞/（C∞-C）]= 0.0723t -0.229 0.9152 0.702 12.08 Advanced Materials Research Vol. 1003 5
- 19. As can be seen from Fig.1 and Table 2, it was found that the derivation of the kinetic equation (6) more in line with the experimental measured data results. The precision of a model can be checked by the determina -tion coefficient (R2 ). The value of the determination coefficient (R2 ) was reasonably close to 1, indicated a high degree of correlation between the observed and predicted values fitting the resulting equation. With increasing power, the apparent rate constant is gradually increased. It was indicate that the increase in power will help speed up the dissolution of the polysaccharides. Conclusions A general mass transfer model for the polysaccharide from Limonium bicolor Kunze (Bge.) with ultrasonic-assisted extraction process is established based on the mass transfer principle in this paper.The results show that the experimental data and kinetic model calculated values are in good agreement. It can provide a theoretical basis for the design of the polysaccharide from Limonium bicolor Kunze (Bge.) with ultrasonic-assisted extraction process and some reference value for similar research. Acknowledgements The authors are grateful for the financial supports to this research from Scientific Research Program Funded by Research Plan in Shaanxi Province, China (No. 2012K19-04-07). References [1] X.H.Tang, M.Shen: Lishizhen Medicine and Materia Medica Research, Vol. 8 (2007) , p.1874 (China). [2] Zhang, L. R, Chen, K. L. Li, N.&Zhou, G. L. (2004). Chemical Journal of Chinese Universities, 11, p.2034-2037 (China) . [3] R.Hofmann, T.Kappler & C. Posten: Separation and Purification Technology, Vol. 51(2006), p.303–309. [4] Z.Hromadkova, A. Ebringerova: Ultrasonics Sonochemistry, Vol.10(2003), p.127–133. 6 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 20. Characterization and photoluminescence of Sr2B2O5:Eu3+ , Na+ red phosphor Lili Ying1, a , Songsheng Zheng1, b , Jianghui Zheng 1, c , Lihan Cai 1, d , Chao Chen*,1 2, e 1 School of Energy Research, Xiamen University, Xiamen, 361005, P.R. China 2 School of Physics and Mechanical & Electrical Engineering, Xiamen University, Xiamen, 361005, P.R. China a liliying1003@gmail.com, b songsheng@xmu.edu.cn, c 89zjh@stu.xmu.edu.cn, d cailihan02@126.com,e cchen@xmu.edu.cn * Corresponding author. Tel. /fax: +86 592 2182458. E-mail address: cchen@xmu.edu.cn Keywords: Phosphors; Luminescence; Borate; Eu3+ ; Abstract. A kind of red emitting phosphor, Sr2B2O5:Eu3+ , Na+ for white light-emitting diodes (W-LED) was synthesized by high-temperature solid-state reaction method. The characterization and luminescence properties of the phosphor were investigated. It is found that this phosphor can be effectively excited by 394 nm near- ultraviolet (n-UV) light, and exhibit bright red emission centered at 613 nm corresponding to the 5 D0→7 F2 transition of Eu3+ ions. It is shown that the 11 mol% of Eu3+ doping concentration in Sr2B2O5:Eu3+ , Na+ phosphor is optimum, and the concentration quenching occurs when the Eu3+ concentration is beyond 11 mol%. The concentration quenching mechanism can be interpreted by the dipole–dipole interaction of Eu3+ ions. The present work suggests that this novel phosphor is a kind of potential red emitting phosphor. 1. Introduction Recently, there has been an upsurge in the research of white-light emitting diodes (W-LEDs), being known as the fourth generation of illumination sources due to their unmatchable benefits , such as high brightness , high color rendering index (CRI), longer lifetime, high luminescence efficiency, low power consumption, and environment-friendliness[1, 2]. The presently commercial W-LED is mainly manufactured by combining a 460nm blue-emitting GaN chip with a yellow- emitting phosphor of Ce3+ doped yttrium aluminum garnet (YAG:Ce3+ ) ,but it suffers from a low color-rendering index and high correlated color temperature(CCT) owing to red emission deficiency in the visible spectrum. To solve this problem, a better route has been proposed to fabricate W-LED by n-UV LED chips coated with RGB (red, green and blue ) tri-color phosphors[3] .There are several phosphors currently available for W-LED application ,such as blue phosphor BaMgAl10O17:Eu2+ [4],green phosphor ZnS:Cu+ /Al3+ [5],and red phosphor Y2O2S:Eu3+ [6].Unfortunately, the sulfide phosphors has low thermal-chemical stability, high toxicity, and inefficient under the excitation of n-UV light with wavelength of 370-410 nm[7]. Therefore, it is highly desirable to develop a new kind of phosphor with high performance for n-UV based W-LED applications. Nowadays, the borate-based phosphor has been paid much attention on account of its low-cost fabrication along with high thermal and chemical stability [8].Examples of these known borate phosphors are, blue phosphor NaSrBO3:Ce3+ [9], green phosphor Na3La2(BO3)3:Ce3+ ,Tb3+ [1],red phosphor La2SrB10O19:Eu3+ [10]etc. In this paper, a kind of red emitting phosphor Sr2B2O5: Eu3+ , Na+ has been synthesized by conventional solid state reaction method at 850 °C. The characterization and photoluminescence properties of Sr2B2O5: Eu3+ , Na+ phosphor have been discussed extensively; meanwhile the dopant concentration of Eu3+ was optimized in order to explore highly efficient phosphors. Advanced Materials Research Vol. 1003 (2014) pp 7-10 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.7
- 21. 2. Experimental A series of Sr2-2xB2O5: xEu3+ , xNa+ phosphors were prepared by high-temperature solid state reaction method. The starting materials were SrCO3 (AR), Eu2O3 (3N), H3BO3 (AR), and Na2CO3 (AR). The stoichiometric materials were weighed and thoroughly mixed in an agate mortar, then transferred to a corundum crucible and pre-calcined at 400 °C for 1 h, subsequently sintered at 850 °C for 3h in air atmosphere. The crystal structure as well as the phase purity of samples was identified by recording X-ray diffraction (XRD) patterns using Rigaku Ultima IV diffractometer with Cu Kα radiation (λ = 0.154 nm) operating at 35kV and 15 mA. The surface morphology and particle size of samples were observed by LEO 1530 scanning electron microscope (SEM). The thermogravimetric analysis (DTA) and derivative thermogravimetric (DTG) curves dependent temperature were obtained by SDT Q600 simultaneous thermo-analytical instrument (TA Instruments-Waters LLC, USA). Photoluminescence excitation and emission spectra were measured by Hitachi F-7000 spectrofluorometer equipped with a 150 W Xenon lamp as an excitation source. All of the measurements were performed at room temperature. 3. Results and discussion Fig.1. (a) shows the XRD pattern of the Sr1.78B2O5:0.11Eu3+ , 0.11Na+ sample and the Inorganic Crystal Structure Database (ICSD) standard pattern. The presenting pattern depicts this phosphor is a single phase and consistent with JCPDs 73-1930. No impurity peaks were detected in the experimental range. It can predict that the doped Eu3+ and Na+ didn’t cause any significant change in host structure and had been efficiently incorporated into the host lattice. According to the ISCD, the crystal structure of Sr2B2O5 phase belongs to the monoclinic space group P21/c with cell parameters a=11.850, b=5.350, c=7.710, V=488.79 Å3 . The corresponding cell parameters of the as-prepared Sr1.78B2O5:0.11Eu3+ , 0.11Na+ from XRD data were refined and calculated to be a=11.880, b=5.342, c=7.736, V=490.94Å3 .It’s found that cell parameters are slightly different form the data of JCPDs 73-1930. In view of the distinct ionic radius among Eu3+ (r=108.7pm), Na+ (r=116pm) and Sr2+ (r=132pm), the incorporation of Eu3+ and Na+ ions is responsible for the distortion. While, the B3+ ions (r=20pm) are too small for Eu3+ or Na+ to occupy. Fig.1 (b) shows the TGA/DTG results of the stoichiometric mixture of SrCO3, Eu2O3, H3BO3 and Na2CO3 heated from room temperature up to 850 °C with a heating rate of 10 °C /min in air. The weight loss before 600 °C was mainly caused by the release of CO2 and H2O from the decomposition of the starting materials. The DTG curve has a conspicuous endothermic peak at around 850 °C, corresponding to a quick weight loss in the interval of that moment temperature, which indicates to the formation of Sr2B2O5 crystalline phase. Thus, the sintering temperature of as-synthesized sample was determined to be 850 °Which is much lower than that of Sr3B2O6:Eu3+ ,Na+[ 11] .The inset of SEM image in fig.1.(b)reveals the surface morphology of the as-synthesized sample and the well-dispersed particles with size ranging in 3–7μm. Fig.1. (a) XRD patterns of Sr1.78B2O5:0.11Eu3+ :0.11Na+ phosphor and standard of JCPDs card No.73-1930(b) The TGA/DTG curves of as-synthesized sample with a heating rate of 10 °C /min in air. Inset is the SEM image of Sr1.78B2O5:0.11Eu3+ :0.11Na+ phosphor 8 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 22. Fig.2. (a) Excitation spectrum (λem=613 nm) and the emission intensity of Sr2−2xB2O5:xEu3+ , xNa+ phosphor with different Eu3+ concentrations (λex=394 nm). (b)The dependence of lgI/x on lgx in the selected Sr2B2O5: Eu3+ , Na+ phosphors (λex=394nm). The excitation spectrum by monitoring the emission at 613 nm (5 D0→7 F2) from Eu3+ ions is depicted in Fig.2 (a). It can be seen that the excitation spectrum consists of a series of sharp peaks at 362nm (7 F0→5 D4), 381nm (7 F0→5 L7), 394nm (7 F0→5 L6), 415nm (7 F0→5 D3), and 465nm (7 F0→5 D2) .The peak intensity at 394nm is the highest one. The emission spectra of Sr1.78B2O5:0.11Eu3+ ,0.11Na+ phosphor under the 394 nm excitation is shown in Fig.2 (a).There are four peaks located at 580nm,593nm,613nm, 621nm,which are attributed to the 5 D0→7 F0,5 D0→7 F1 ,5 D0→7 F2 and 5 D0→7 F2 transitions of Eu3+ ions respectively and the red emission at 613nm is dominated. Therefore, Sr2B2O5: Eu3+ , Na+ phosphor can be well excited by 394nm and emit red light. The emission spectra of Sr2−2xB2O5:xEu3+ , xNa+ phosphor with various Eu3+ concentrations excited by 394 nm near UV light are shown in Fig.2 (a), which display the similar spectrum except for the luminescence intensity. It is confirmed that the crystalline phase did not change a lot with doping different Eu3+ concentrations. The highest integrated emission intensity is noted at the Eu3+ concentration of x=0.11, which is taken as the critical concentration. Lower doping concentrations can lead to weak luminescence and higher dopants will cause concentration quenching of the Eu3+ emission. Since the fluorescence mechanism of Eu3+ in Sr2B2O5:Eu3+ , Na+ phosphors is the electric multiple-multiple interaction by Dexter theory[12].If the energy transfer occurs between the same sort of activators, then the intensity of multipolar interaction can be determined from the change of the emission intensity from the emitting level which has multipolar interaction. The emission intensity (I) per activator ion is given by the equation [13, 14]: I/x=K [1+β(x) Q/3 ]-1 . (1) Where I is the emission intensity of Sr2−2xB2O5:xEu3+ , xNa+ phosphor, x is the activator Eu3+ concentration; Q =6, 8, or 10 is for dipole–dipole (d–d), dipole–quadrupole (d–p), or quadrupole– quadrupole (q–q) interaction, respectively; and K and β are constants for the same excitation condition for a given host crystal. When x is larger than the critical quenching concentration, Eq. (1) can approximately be simplified as Eq. (2) for β(x) Q/3 >>1, where A is a constant. lg(I/x)=A-Q/3lgx. (2) Since the critical concentration of Eu3+ has been determined as 11mol%, the dependence of the emission intensity of the as-synthesized phosphors on corresponding concentration of Eu3+ which is not less than the critical concentration is determined. The plot of lgI/x as a function of lgx is shown Advanced Materials Research Vol. 1003 9
- 23. in Fig.2. (b). It shows that the dependence of lgI/x on lgx is linear and the slope of the fitting line is -1.917.According to the Eq. (2), the value of Q can be calculated as 5.751, which is approximately 6. It indicates that the dipole–dipole (d–d) interaction is the main concentration quenching mechanism of Eu3+ emission in Sr2B2O5: Eu3+ , Na+ phosphors. 4. Conclusions In conclusion, the Sr2B2O5:Eu3+ , Na+ phosphors have been synthesized by solid-state reaction. The emission spectrum indicates that the as-synthesized phosphor emits bright red emission centered at 613nm under 394nm excitation. And the optimum concentration of Eu3+ is testified to be 11mol%. The concentration quenching mechanism of Eu3+ ions in Sr2B2O5:Eu3+ , Na+ phosphor is the dipole– dipole interaction. Therefore, Sr2B2O5:Eu3+ , Na+ phosphor is a promising red phosphor for near-UV LED applications. Acknowledgements This work was financially supported by National Natural Science Foundation of China (No. 61076056). References [1] M. Yang, L. Liu, F. Chen, Materials Letters, 88 (2012) 116-118. [2] A.A. Reddy, S. Das, A. Goel, R. Sen, R.e. Siegel, L.s. Mafra, G.V. Prakash, J.M.F. Ferreira, AIP Advances, 3 (2013) 022126. [3] J.K. Sheu, S.J. Chang, C.H. Kuo, Y.K. Su, L.W.Wu, IEEE Photonics Technology Letters, 15 (2003) 18-20. [4] S.W. Ko, D. Shin, Journal of Electroceramics, 23 (2008) 410-414. [5] A. Suzuki, S. Shionoya, Journal of the Physical Society of Japan, 31 (1971) 1455-1461. [6] S.-H. Рагк, S.-i. Mho, K.-W. Lee, Notes, 17 (1996) 487. [7] P. Li, Z. Xu, S. Zhao, F. Zhang, Y. Wang, Materials Research Bulletin, 47 (2012) 3825-3829. [8] L. Cai, L. Ying, J. Zheng, B. Fan, R. Chen, C. Chen, Ceramics International, 40 (2014) 6913-6918. [9] W.-R. Liu, C.-H. Huang, C.-P. Wu, Y.-C. Chiu, Y.-T. Yeh, T.-M. Chen, Journal of Materials Chemistry, 21 (2011) 6869. [10] R. Guo, S. Tang, B. Cheng, D. Tan, Journal of Luminescence, 138 (2013) 170-173. [11] R. Wang , J. Xu , C. Chen Chinese journal of luminescence, 30 (2011-10) 983-987. [12] D.L. Dexter, J.H. Schulman, The Journal of Chemical Physics, 22 (1954) 1063. [13] I.G.V. Uitert, Journal of the electrochemical society, 114 (1967) 1048-1053. [14] L. Ozawa, P.M. Jaffe, Journal of the electrochemical society, 118 (1971) 1678-1679. 10 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 24. Synthesis and Fluorescence Properties of a New Eu(III) Complexes with β-Diketone Ligand Ya Nan Lu a , Xiong Yan Zhao b* , and Xin Wang c College of Material Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, P. R. China a email: 370555496@qq.com, b* email: zhaoxy66@126.com, c email: xin.wang.hebust@gmail.com Keywords: β-diketone, rare earth ions, thermal stability, fluorescence property Abstract. A novel β-diketone 4-[4-(Dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD) and its corresponding Eu3+ complex with 1,10-phenanthroline were synthesized. The structure, thermal behaviour and fluorescence property of the complex was characterized by Fourier Transform Infrared (FT-IR), thermal gravimetric analysis (TGA) and fluorescence spectrophotometer. The fluorescence characterization shown that the addition of β-diketone and 1,10-phenanthroline enhance the fluorescence intensity of the complex. Eu3+ complex was considered to be a valuable organic light-emitting material with bright red fluorescence because of its strong emission band. Furthermore, the thermal stability characterizarion shows that the obtained rare earth β-diketone complexes have good thermostability. Introduction Rare earth complex is a kind of luminescent materials that has unique photoluminescence properties, good monochromaticity and high fluorescence intensity which has attracted increasing attention recent years[1]. Rare earthEu3+ and Tb3+ have excellent fluorescence and monochromaticity, their f→f transition appears in the visible area[2-3], but the strength and efficiency of luminescence are reduced because of their f→f transition are forbidden. Therefore, a new type of organic ligands that have larger π electron conjugated system, strong UV absorption, above all, can coordination and excitation rare earth ions need to be designed and prepared[4-5]. β-diketone with a high absorption coefficient and appropriate conjugated system is a kind of good organic chelating ligand, it can sensitize and has strong coordination ability with rare earth ions[6-7]. Generally, a second ligand is added to meet the coordination number of center rare earth ions[8-10]. In order to obtain new rare earth fluorescence materials with effective luminescent properties, a new type of β-diketone ligand was synthesized in this work. Research shows that adding aromatic rings with nitrogen atoms, such as 1,10-phenanthroline can enhance rare earth’s fluorescence. We have synthesized a novel rare-earth complex possessing β-diketone and 1,10-phenanthroline in this research and its fluorescence properties were discussed in details. Experimental Materials. 4-Aminoacetophenone(99%) was obtained from Alfa Aesar, benzylbromide(CP) and europium oxide(Eu2O3, EP) were both purchased from Sinopharm Chemical Reagent Co. Ltd, 1,10-phenanthroline(Phen) and other reagents were commercial products without further purification. Europium chlorides were obtained by dissolving its oxides (Eu2O3) into concentrated hydrochloric acid. Advanced Materials Research Vol. 1003 (2014) pp 11-14 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.11
- 25. Synthesis of 1-[4-(dibenzylamino)phenyl]ethanone(DBMPE). 4-aminoacetophenone(12.16 g 90mmol), benzylbromide(34.2 g 0.2 mol), K2CO3(27.6 g) and KI(0.5 g) were all dissolved in appropriate amount of DMF(300ml), added the solution into a 500 ml three-necked bottle with stirring at 120 ℃ for 48 hours. The supernatant was left after experiment and the solvent was removed by reduced pressure distillation. The final products were obtained by washing and recrystallized by ethanol. Synthesis of 4-[4-(dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD). 15 mmol ethyl acetate and 10 mmol DBMPE were added into a 100 ml three necked bottle with stirring under nitrogen at 20℃ for 15 minutes. 50 mmol sodium cyanide were added into the bottle and the reaction temperature was fixed at 20℃. After stirring of 5 hours at a constant speed, the final products were obtained followed by pH adjustment, dichloromethane extraction, water elimination, vacuum-rotary evaporation and separation and purification by silica gel column chromatography. Synthesis of Eu(DPD)3phen. 4.5 mmol DPD, 1,10-phenanthroline and sodium hydroxide were dissolved in ethanol, respectively. All the three solutions were blended and poured into a three necked bottle with a condenser. After reacted at 60℃ for 20 minutes, europium chlorides were added into the bottle by drop wise manner. After reacted for 2 hours, the Eu(DPD)3phen precipitate were obtained by vacuum filtration. Results and Discussion Structure analysis of the rare earth complexes. The FTIR spectrum of complex was shown in Fig.1. The absorption band observed at 1580cm-1 is the stretching vibration peak of C=O in β-diketone. The band at 1424.6 and 1495.8cm−1 are attributed to the bending vibration of C-H and combined effect of stretching vibration of C=O, C=N in Phen, respectively. In addition, two bands at 842.4 and 729.8cm-1 are attributed to the bending vibration of hydrogen atoms on benzene rings. After β-diketone was chelated with rare earth ion, the bands of C=O, C=N, C=C were weaken by conjugate structure of C=O-Eu and lead to vibration peak redshift. The bands at 458 and 530.8 cm-1 are attributed to the stretching vibration of Eu-O and Eu-N in complex. 3500 3000 2500 2000 1500 1000 500 0 20 40 60 80 100 1399.1 1495.8 1580.3 842.4 729.8 458 Transmittance(%) Wavenumbers(cm-1) Fig. 1 FT-IR spectra of the complex 12 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 26. Thermal properties. The TGA curve of rare earth β-diketone complexes was shown in Fig.2. It can be seen that there is no mass loss occurs below 200℃ which indicates the absence of water molecular in its structure. A further increase of temperature leads the complex decompose intensely at about 300℃ and decompose complete at 600℃. The mass loss of complexes is percentage 73.87% according to the calculation. The mass loss between 300℃ and 600℃ is attributable to the decomposition of free ligands DPDand second ligand phen. This result shows that the β-diketone complexes have good thermostability. Fig. 2 TGA curve of the complex Fluorescence properties. The fluorescence characteristics of the complex in solid state are characterized by fluorescence spectrophotometer and the date are listed in Table 1. The corresponding fluorescence spectra are shown in Fig.3. Table 1 Fluorescence spectra date of Eu(DPD)3phen Complexes λex（nm) λem(nm) Emission Intensity(a.u.) Transition Eu(DPD)3phen 306 580 82 5 D0→7 F0 590 64 5 D0→7 F1 613 6139 5 D0→7 F2 652 7 5 D0→7 F3 706 3 5 D0→7 F4 Because of the π→π* transition on the ligand, the maximum intension of excitation spectra of the complexes are observed at 306 nm. The 5 D0→7 F1 transition of Eu+ is magnetic dipole transition, the emission intensity is not affected by the coordination of rare earth ions. The 5 D0→7 F2 transition is electric dipole transition, the coordination environment has strong influence on its emission intensity, so it is also known as ultrasensitive transition. It is clear from Fig.3 that the intension of 5 D0→7 F2 transition is much stronger than 5 D0→7 F1 transition. This result indicates that the coordination environment of Eu+ ions have low symmetry. It leads that the complexes have good monochromaticity and the addition of ligands enhanced the fluorescence intensity of complexes. Advanced Materials Research Vol. 1003 13
- 27. 200 300 400 500 600 700 0 1000 2000 3000 4000 5000 6000 7000 5 D0 → 7 F4 5 D0 → 7 F3 5 D0 → 7 F2 5 D0 → 7 F1 5 D0 → 7 F0 Fluorescence Intensity(a.u.) Wavelength(nm) Fig.3 Fluorescence spectra of complex Eu(DPD)3phen Conclusions In this work, a novel β-diketone ligand 4-[4-(Dibenzylamino)phenyl]-2,4-dioxobutanoic(DPD) and its corresponding complex Eu(DPD)3phen were synthesized and characterized. The FT-IR spectrum indicates that the oxygen atoms of β-diketone and the nitrogen atoms of phen were coordinated to the Eu3+ ion. The excitation spectra and emission spectra show Eu3+ complex has strong fluorescence at 613 nm and emits a strong red luminescence. Due to its good thermal stability, it can be used as promising candidates for applications in organic light-emitting materials. Acknowledgements The Project was supported by the Hebei Province Science and Technology Support Project (Grant No. 14210309D). References [1] S.S. Yang, Q.S. Song, K. Gao: Solid State Sciences Vol. 34 (2014), p. 17-23 [2] Y.J. Li, B. Yan, Y. Li: Journal of Solid State Chemistry Vol. 183 (2010), p. 871-877 [3] A. Ege, M. Ayvacikli, O. Dinçer, et al: Journal of Luminescence Journal of Luminescence Vol. 143 (2013), p. 653-656 [4] D.Z. Ma, Y.Q. Wu, X. Zuo: Materials Letters Vol. 59 (2005), p. 3678-3681 [5] R.R. Tang, W. Zhang, Y.M. Luo, et al: Journal of rare earths Vol. 27 (2009), p. 361-367 [6] X.W. Liu, N. Wang, Q.L. Suo: Journal of rare earths Vol. 26 (2008), p. 778-782 [7] X.W. Liu, J.D. Jiang, S.L. Yong, et al: Journal of rare earths Vol. 30 (2012), p. 520-523 [8] H.F. Jiu, G.D. Liu, Z.J. Zhang, et al: Journal of rare earths Vol. 29 (2011), p. 741-745 [9] Y.F. Zhang, Z. Xu, Y.G. Lü, et al: Journal of rare earths Vol. 25 (2007), p. 143-147 [10] Y.G. Lü, G. Li, C.H. Shi, et al: Transaction of Nonferrous Metals Society of China Vol. 20 (2010), p. 2336-2339 14 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 28. Synthesis and Photochromism studies of 1-(3,5-dimethyl-4-isoxazole)-2-[2-methyl-5-naphthyl-3-thienyl] perfluorocyclopentene Xiaorong Dong, Renjie Wang*, Gang Liu and Shouzhi Pu Jiangxi key laboratory of Organic Chemistry, Jiangxi Science & Technologe Normal University, Nanchang 330013, P. R. China bio-wrj@163.com Keywords: Diarylethene; Photochromism; Fatigue Resistance; Kinetic; Abstract. A new class of unsymmetrical photochromic diarylethene bearing an isoxazole moiety was synthesized. Its photochemical properties, including photochromic behavior and kinetics, have been investigated systematically. The result indicated that the Diarylethene 1a changed the color from colorless to pink irradiation with 297 nm UV light, in which absorption maxima were observed at 522 nm in hexane. The photochromic reaction kinetics indicated that the cyclization processes of 1a belong to the zeroth order reaction and the cycloreversion process belong to the first order reaction. Introduction Photochromism, a photoinduced reversible reaction between two isomers, is one of the essential photochemical reactions to facilitate the reversible fluorescence switching process in synthetic molecules as well as fluorescence proteins [1-4]. Photochromic dithienylethenes are considered to be among the most promising systems for applications in optical memory media and switching devices due to their excellent photochromic properties coupled with thermal stability, fatigue resistance, and sensitivity [5-9]. Therefore, current research interest is focused on the introduction of heterocycles to obtain novel photochromic materials with excellent properties. In the past several decades, numerous studies have focused on molecular design, especially the symmetric and asymmetric synthesis of organic frameworks in diarylethenes with different heteroaryl units such as thiophene or benzothiophene[10-12]. It has been revealed that the aryl moieties and the functional substituents have critical effects on photochromic properties. In particular, diarylethenes with different substituted ring systems have been of considerable interest, which different substituted ring could be resulted in different color change before and after light irradiation. In this research work, a new unsymmetrical photochromic diarylethene bearing an isoxazole moiety compound 1a was synthesized and its photochemical properties, such as photochromism in solution as well as in PMMA amorphous film can be easily obtained. The photochromic reaction of diarylethene 1a is shown in Scheme 1. F F F F F F S N O F F F F F F S N O UV Vis 1o 1c Scheme 1. Photochromism of diarylethene 1a. Experiments Synthesis of diarylethene 1a. Synthetic route for diarylethene 1a is shown in Scheme 2. Diarylethene 1a was characterized by 1 H NMR . 1 H NMR (400 MHz, CDCl3): δ 2.12 (s, 3H, -CH3), Advanced Materials Research Vol. 1003 (2014) pp 15-18 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.15
- 29. 2.33 (s, 3H, -CH3), 2.43 (s, 3H, -CH3), 7.44 (s, 1H, thiophen-H), 7.58 (t, 3H, J = 6.4 Hz, anphthyl-H), 7.72 (d, 1H, J = 6.0 Hz, phenyl-H), 7.92 (t, 3H, J = 6.0 Hz, anphthyl-H); 13 C NMR(100 MHz, CDCl3): δ 10.7, 12.1, 14.4, 29.7, 124.3, 124.9, 125.2, 126.2, 126.7, 126.9, 127.4, 127.7, 128.0, 128.5, 128.8, 129.1, 130.8, 131.5, 133.9, 140.6, 142.0. N O I Br2 1. CS2, ice-bath 2. Acetic acid N O Br C5F8 n-BuLi,195K F F F F F F F N O S Br n-BuLi,195K F F F F F F S N O 1a Scheme 2. Synethesis of diarylethenes 1a. Results and Discussion Photochromism of 1a in solution and PMMA film. The novel diarylethene 1o exhibits good photochromic properties both in hexane and in PMMA film. Fig. 1A shows the absorption spectral and color changes of 1a in hexane (2.0 × 10−5 mol L-1 ). The maximum absorption of the colorless 1a was observed at 297 nm in hexane. Upon irradiation with 297 nm light, the colorless solution of 1o turned to pink, in which absorption band was observed at 522 nm. The pink color was due to form the closed ring isomer 1c. The color could bleach by irradiation with visible light (λ > 500 nm). Similarly, the color could change upon UV light (297 nm) irradiation in PMMA film (Fig. 1B). Upon irradiation with 297 nm UV light, the color of 1a/PMMA film changed from colorless to pink with the appearance of a new absorption band centered at 522 nm, which was assigned to the formation of the closed-ring isomer 1c. The colored PMMA film can invert to colorless upon irradiation of appropriate visible light (λ > 500 nm). 300 400 500 600 700 0.0 0.1 0.2 0.3 0.4 Absorbance Wavelength (nm) Vis UV Vis UV A 300 400 500 600 700 0.0 0.1 0.2 0.3 0.4 Absorbance Wavelength (nm) Vis UV Vis UV B Fig.1 Absorption spectral changes of compound 1a in hexane (A) and in PMMA film (B). Photochromic reaction kinetics in hexane solution. The photochromic cyclization/cycloreversion kinetics of 1a in hexane were determined by UV-Vis spectra upon alternating irradiation with UV and appropriate wavelength visible light at room temperature. The cyclization and cycloreversion curves of 1a were shown in Fig. 2. It can be seen that the relationships between the absorbance and exposal time have good linearity upon irradiation with 297 nm UV light suggesting that the cyclization processes of 1o belong to the zeroth order reaction when open-ring isomer changed to closed-ring isomer. The slope of every line in Fig. 2 represents the reaction rate constant (k) of diarylethene 1a in hexane. As shown in Fig. 2B, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also behave perfect linearity, indicating that the cycloreversion process belong to the first order reaction. So k of cyclization process (ko-c, 10-3 ) of diarylethene 1o 16 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 30. and k of cycloreversion (kc-o, 10-3 ) process of 1c were 1.01 mol L-1 s-1 and 1.47 s-1 in hexane, respectively. 0 10 20 30 40 0.01 0.02 0.03 0.04 0.05 0.06 (A) Abs Time (s) R=0.99593 Y = 0.01606 + 0.00101 * X 0 5 10 15 20 25 0.98 0.99 1.00 1.01 1.02 -log(Abs) Time (s) (B) R=0.99753 Y = 0.97959 + 0.00147 * X Fig. 2 The cyclization kinetics (A) and cycloreversion kinetics (B) of compound 1a in hexane. The fatigue resistance of 1a in solution and PMMA film. The fatigue resistance [13-14] of diarylethene 1a was tested in both hexane and PMMA film at room temperature, and the result is presented in Fig. 3. In hexane, the coloration and decoloration cycles of 1a could repeat more than 100 times with the degradation of 35% for 1c. After repeating 200 times in PMMA film, diarylethene 1a still exhibited favorable photochromism with the degradation of 30% for 1c. Therefore, diarylethene with an isoxazole moiety exhibited fatigue resistance in both hexane and PMMA film. 20 40 60 80 100 0.00 0.25 0.50 0.75 1.00 A/A 0 (%) Repeat Cycles (A) 50 100 150 200 0.00 0.25 0.50 0.75 1.00 A/A 0 (%) Repeat Cycles (B) Fig. 3 Fatigue resistance of diarylethene 1a in air atmosphere at room temperature in hexane (A) and in PMMA film (B). Initial absorbance of the sample was fixed to 1.0. Summary A new unsymmetrical photochromic diarylethene was synthesized. Its photochromic property and the kinetic reactions were investigated by UV-Vis spectra in hexane solution. The present result indicated that the diarylethene has good photochromic properties. Furthermore, the compound also exhibited fatigue resistance. Acknowledgment The authors are grateful for the financial support from the National Natural Science Foundation of China (21262015). Advanced Materials Research Vol. 1003 17
- 31. References [1] M.-M. Russew and S. Hecht: Adv. Mater. Vol. 22 (2010), p. 3348 [2] Q. Wei and A. Wei: Chem.–Eur. J. Vol. 17 (2011), p. 1080 [3] M. Irie, T. Sasaki, N. Tamai and T. Kawai: Nature, Vol. 420 (2002), p. 759 [4] A. Bianco, G. Lanzani and C. Bertarelli: Photonics Rev. Vol. 5 (2011), p. 711 [5] M. Irie: Chem Rev. Vol. 100 (2000), p. 1685 [6] S. Kobatake and Y. Terakawa: Tetrahedron Lett. Vol. 52 (2011), p. 1905 [7] H. Tian, S.J. Yang: Chem Soc Rev. Vol. 33 (2004), p. 85 [8] H. Tian, Y.L. Feng: J Mater Chem. Vol. 18(2008), p. 1617 [9] A. Bianco, C. Bertarelli and G. Zerbi: Chem Mater. Vol. 17 (2005), p. 869 [10] S.Z. Pu, J.K. Xu, Q. Xiao and B. Chen: Mater. Lett. Vol. 60 (2006), p. 685 [11] S. Kobatake, H. Muto, T. Ishikawa and M. Irie: Nature Vol. 446 (2007), p. 778 [12] X.D. Deng and L.S. Liebeskind: J. Am. Chem. Soc. Vol. 123 (2001), p. 7703 [13] H. Tian and S.J. Yang: Chem. Soc. Rev. 33 (2004), p. 85 [14] M. Irie: Chem. Rev. 100 (2000), p. 1685 18 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 32. Research on Photochromic Materials with Synthesis and Properties of a New Unsymmetrical Diarylethene 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)p henyl]-3-thienyl} Perfluorocyclopentene Fang Duan and Gang Liu* Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, P. R. China liugang0926@163.com Keywords: Diarylethene; Photochromism; Kinetics; Fluorescence. Abstract. A new photochromic diarylethene having a pyrrole unit, which is named 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)phenyl]-3-thienyl}perflu orocyclopentene, was designed and constructed successfully. And its properties have been discussed systematically, including photochromic, fluorescence switch and kinetics experiments in acetonitrile solution. The results showed that its photochromic behaviors could be modulated by UV/Vis light, changing from colorless to blue in acetonitrile solution. What is more, the kinetic experiments illustrated that the cyclization/cycloreversion process of this compound was determined to be the zeroth/first reaction. Introduction Photochromic materials are a family of compounds which can undergo reversible photo-switches between two different isomers having remarkably various properties [1]. Photochromic compounds are the most promising candidates for photoelectronic applications, such as optical memory, chemical sensor, and molecular switching, because of their thermally-irreversible and fatigue-resistant photoisomerization performances [2]. During the past decades, the majority of the study work reported has been devoted to the development of these molecules and investigative studies of their fundamental properties [3-5]. Up to date, design and synthesis of new photochromic compounds is an active area of research, and many publications concerning synthesis and investigation of the properties of diarylethenes with the heterocyclic aryl rings have been reported [6–8]. Among these novel photochromic diarylethenes, there are few examples of photochromic diarylethenes bearing pyrrole rings. This special structural characteristic may be in favor of photochromic reaction. On the basis of these considerations, we design a new class of hybrid photochromic diarylethene derivatives bearing a pyrrole moiety. In this paper, we designed and synthesized a new diarylethene, namely 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-{2-methyl-[5-(4-methylene-bromine)phenyl]-3-thienyl}perflu orocyclopentene 1o. Its photochromic reactivity, kinetics and fluorescence were investigated in detail. The photochromic reaction of diarylethene 1o is shown in Scheme 1. N NC F F F F F F S Br UV Vis N NC F F F F F F S Br 1o 1c Scheme 1. Photoisomerization of 1o Advanced Materials Research Vol. 1003 (2014) pp 19-22 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.19
- 33. Experiments. Synthsis of diarylethene 1o. The target diarylethenes were synthesized by the method as shown in Scheme 2. It was synthesized according to the similar procedure of Pu et al [9]. The structure of compound 1o was characterized by 1 H NMR spectroscopy. NMR spectra were recorded on Bruker AV400 (400 MHz) spectrometer with CDCl3 as the solvent and tetramethylsilane as an internal standard. 1 H NMR (400 MHz, CDCl3, TMS): δ 1.70 (s, 3H,-CH3), 1.90 (s, 3H,-CH3), 3.54 (s, 3H,-CH3),4.53 (s, 2H,-CH2), 6.86 (s, 1H, thiophene-H), 7.19 (s, 1H, thiophene-H), 7.34 (d, 2H, J = 8.0 Hz, benzene-H), 7.47(d, 2H, J = 8.0 Hz, benzene-H). N NC Br2 N NC Br C5F8 N NC F F F F F F F S Br CHO N NC F F F F F F S N NC F F F F F F S CHO NaBH4 THF N NC F F F F F F S CH2OH LiBr THF DMC 三 三 三 三乙 乙 乙 乙胺 胺 胺 胺 N NC F F F F F F S Br S Br Glycol Toluene Reflux 6 O O O O Py, TsOH Acetone H2O Reflux 8 7 2 3 4 5 9 1o Scheme 2. Synthesis of diarylethene 1o Results and discussion Photochromism of diarylethene 1o in acetonitrile solution. The diarylethene 1o exhibited good photochromic properties and could be toggled between its colorless ring-open and colored ring-closed forms by alternate irradiation with appropriate wavelengths of light. The absorption spectral changes in acetonitrile are shown in Fig. 1. The open ring isomer had an absorption maximum at 301 nm which was arisen from π→π* transition [10] . Upon irradiation with 297 nm light, the colorless solution of 1o turned to blue due to the appearance of a new broad absorption band at λ = 617 nm defined as the formation of the closed-ring isomer 1c. Then, the blue colored solution reverted to colorless upon irradiation with visible light (λ > 450 nm), indicating that 1c returned to the initial state 1o, and a clear isosbestic point was observed at 322 nm. From the above description, we can easily get a conclusion that both open-ring isomer and closed-ring isomer of this diarylethene were stable in solution at room temperature. Fig. 1 Absorption spectra upon alternating irradiation with UV-Vis light of the compound 1o in acetonitrile (2.0 × 10-5 mol/L). 20 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 34. Photochromic reaction kinetics in acetonitrile solution. The photochromic cyclization and cycloreversion kinetics of this diarylethene in acetonitrile were determined by UV-Vis spectra upon alternating irradiation with appropriate wavelength UV and visible light at room temperature. The cyclization and cycloreversion curves of compound 1 are shown in Fig. 2, respectively. It can be seen that the relationships between the absorbance and exposal time have good linearity upon irradiation with 297 nm light (Fig. 2A). It is suggesting that the cyclization process of compound 1o belong to the zeroth order reaction when open-ring isomer changed to closed-ring isomer. At the same time, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also behave perfect linearity, as shown in Fig.2 (B), indicating that the cycloreversion process belong to the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3 ) of diarylethene 1c can be easily obtained in solution, respectively. 0 10 20 30 40 -0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 A Y=-0.00213+0.00162*X R=0.99299 Absorbance Time/s 0 10 20 30 40 50 60 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Y=0.79934+0.02121*X R=0.9973 -log( Abs) Time/s B Fig. 2 The cyclization (A) and cycloreversion (B) kinetics of compound 1o in acetonitrile. Fluorescence of diarylethene . Fluorescent properties can be useful not only in molecularscale optoelectronics, but for digital photoswitching of fluorescence. In this work, the fluorescence properties of the diarylethene1o in solution (2 × 10-5 mol/L) was measured using a Hitachi F-4600 spectrophotometer, and the breadths of excitation and emission were selected 5.0 nm and 10.0 nm. The fluorescence excitation and emission spectra of 1o in acetonitrile (2 × 10-5 mol/L) at room temperature was illustrated in Fig. 3. From Fig. 3, we can clearly see that the acetonitrile of diarylethene 1o exhibited relatively strong fluorescence at 368 nm when excited at 240 nm. The Stokes shift of the fluorescence was relatively large and the fluorescence spectral edge showed a red-shift in comparison with the absorption edge. This kind of large Stokes shift has already been discussed in detail by Sekiya and coworkers [11]. 200 250 300 350 0 500 1000 1500 350 400 450 500 550 0 1000 2000 3000 4000 5000 Emission Intensity (a.u.) Ex Wavelength/nm Em Fig. 3 Excitation spectra (-) and fluorescence spectra (-) of 1o in acetonitrile Fig.4 shows the fluorescence spectral changes of 1o. Diarylethene 1o exhibited good fluorescence in acetonitrile solution, and the values are 368 nm. The fluorescence intensity of diarylethene 1o decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer in acetonitrile. The back irradiation by appropriate wavelength visible light regenerated the open-ring form of diarylethene 1o and recovered the original emission spectra. The incomplete Advanced Materials Research Vol. 1003 21
- 35. cyclization reaction and the existence of parallel conformations may be the main cause for the moderate change in fluorescence induced by photoirradiation. The reversible changes of the emission intensity of diarylethene 1o are useful for application as the fluorescence switches. 360 370 380 390 400 500 1000 1500 2000 2500 3000 3500 Emission Intensity (a.u.) Wavelength /nm Vis UV Fig. 4 Fluorescence spectra of diarylethene 1o in acetonitrile (2.0 × 10-5 mol/L) excited at 240 nm upon irradiation with 297 nm UV light at room temperature. Summary In conclusion, a novel diarylethene was synthesized to investigate its photochromism, kinetic and fluorescence. Diarylethene 1o exhibited photochromism in acetonitrile solution and relatively strong fluorescence at 368 nm when excited at 240 nm. The results will be helpful for the synthesis of efficient photoactive diarylethene derivatives with fluorescence switches. Acknowledgment The authors are grateful for the financial support from the National Natural Science Foundation of China (21262015). References [1] J. J. Zhang, Q. Zou and H. Tian: Adv. Mater. Vol. 24 (2012), p. 1 [2] M. Natali and S. Giordani: Chem. Soc. Rev. Vol. 41 (2012), p. 4010 [3] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu and T.S. Yang: Dyes and Pigments Vol. 90 (2011), p. 71 [4] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron Vol. 67 (2011), p. 1438 [5] G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980 [6] H. Nishi and S. Kobatake: Macromolecules. Vol. 41 (2008), p. 3995 [7] Q. F. Luo, H. Cheng and H. Tian: Polylm. Chem. Vol. 2 (2011), p. 2435 [8] R. J. Wang, S. Z. Pu, G. Liu, S. Q. Cui and H. Li: Tetrahedron Lett. Vol. 54 (2013), p. 5307 [9] S. Z. Pu, G. Liu, and J. K. Xu. Org. Lett. Vol. 9(2007), p.2139. [10]Z.X. Li, L.Y. Liao, W. Sun, C.H. Xu, C. Zhang, C.J. Fang and C.H. Yan: J. Phys. Chem. C. Vol. 112 (2008), p. 5190S. [11]N. Tanaka, C. Okabe, K. Sakota, and M. Irie:J. Mol. Struct. Elsevier, Amsterdam. vol. 616(2002),p. 113. 22 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 36. Research on Photochromic Compounds with Synthesis and Properties of a Novel Unsymmetrical Diarylethene with a Benzothiophene and a Pyrrole Group Hongjing Jia, Yinglong Fu and Congbin Fan * Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, P. R. China congbinfan@163.com Keywords: Unsymmetrical Diarylethene, Photochromic, Kinetics, Optical Storage. Abstract. A new unsymmetrical photochromic diarylethene 1o, which is named [1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)]perfluorocyclopentene, was synthesized. We used it to accomplish recording by optical storage technology as memory medium. Then its photochromic both in hexane solution and in PMMA film and kinetics experiment were investigated in detail. The result indicated that this diarylethene had good thermal stability and exhibited reversible photochromism, changing the color from colorless to violet in hexane solution upon appropriate irradiation with 297 nm UV light, respectively. What is more, the kinetic experiments illustrated that the cyclization/cycloreversion process of this compound was determined to be the zeroth/first reaction. The results demonstrated that the unsymmetrical diarylethene compound 1o, which we have synthesized, had attractive properties for potential application in optical storage. Introduction During the past several decades, there have been reported various kinds of photochromic compounds, such as azobenzenes [1], spirobenzopyrans [2], fulgides [3], and so on. Among them, diarylethene derivatives are regarded as the best promising candidates for such devices, due to their good thermal stability and remarkable fatigue resistant performances required for optoelectronic applications [4,5], representatively their potential applications including optoelectronics such as optical recording, photo-switching, and full-color display devices [6-8]. Therefore, it is especially important to synthesize diarylethene derivatives and research their structural features. In previous papers, a large number of publications concerning synthesis and investigation of their photochromic properties of diarylethene have been reported [9,10]. To the best of our knowledge, most of the papers concentrated on symmetrical compound. However, there are few publications report photochromic unsymmetrical hybrid diarylethene derivatives with benzothiophene and pyrrole moieties. According to the above aspects, in this work, a new unsymmetrical diarylethenes 1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)perfluorocyclopentene 1o was synthesized. Then, the photochromic properties and kinetics experiment were discussed and investigated in detail. The photochromic reaction of diarylethene 1o is shown in Scheme 1. Scheme 1. Photoisomerization of diarylethene 1o Advanced Materials Research Vol. 1003 (2014) pp 23-26 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.23
- 37. Experiments Synthsis of diarylethene 1o. Diarylethene 1o, 1-(2-methyl-benzothiophene)-2-(2-cyano-1,5-dimethyl-4-pyrryl)perfluorocyclopentene, was prepared based on the method described in Scheme 2. It was synthesized according to the similar procedure of Pu et al. [11]. First, the compound 2-methylbenzothiophene 3 were obtained by alkylate reaction. Then to a stirred solution of 3 in THF, Br2 was added dropwised at room temperature gave compound 4. Meanwhile, 1,5-dimethyl-1H-pyrrole-2-carbonitrile 5 was slowly added Br2/acetic acid mixture solution to give 4-bromo-1,5-dimethyl-2-pyrrolecarbonitrile 6. Compound 7 was obtained by lithiated and coupled with octafluorocyclopentene. Finally compound 4 was further lithiated and then coupled with compound 7 to give the product diarylethene 1o. After extracting with ethyl acetate and evaporation in vacuum, the residue was purified by column chromatography on silica gel (petroleum ether/ethyl acetate = 3:1) to obtain the target compound 1o. The structure of compound 1o was confirmed by 1 H NMR spectroscopy. NMR spectra were recorded on Bruker AV400 (400 MHz) spectrometer with CDCl3 as the solvent and tetramethylsilane as an internal standard.1 H NMR (400 MHz, CDCl3, TMS): δ 1.75 (s, 3H, -CH3), 2.30 (s, 3H, -CH3), 3.51 (s, 3H, -CH3), 6.77 (s, 1H, pyrrole-H), 7.30-7.36 (m, 2H, benzene-H), 7.48 (d, 1H, J = 8.0 Hz, benzene-H), 7.74-7.77 (m, 1H, benzene-H). Preparation of PMMA Film. 100 mg of PMMA was first dissolved in 1 mL chloroform, which was stirred ultrasonically to make it homogeneous. Samples were obtained by dissolving ultrasonically 10 mg of compounds 1 with 1 mL of the PMMA solution, respectively, and the solution was spin-coated on a glass substrate with a spin rotation speed of 1500 rpm. Scheme 2. Synthesis of diarylethene 1o Results and Discussion Photochromism of the diarylethene 1o. The changes in the absorption spectra of diarylethene 1o, which were induced by photoirradiation at room temperature in hexane (2.0 × 10-5 mol/L) are shown in Fig.1. Upon irradiation with 297 nm UV light, the colorless solution of 1o turned to voilet due to the appearance of a new broad absorption band at λ = 547 nm assigned to the formation of the closed-ring isomer 1c. Then, the voilet colored solution reverted to colorless upon irradiation with visible light (λ > 500 nm), indicating that 1c returned to the initial state 1o, and a clear isosbestic point was observed at 248 nm. Similarly, the photochromism of diarylethene 1o in the PMMA amorphous film is shown in Fig. 1B. In PMMA film, upon irradiation 297 nm UV light, the color of 1o/PMMA film changed from colorless to voilet due to the formation of the closed-ring isomer 1c, accompanied by a new broad absorption band at 572 nm appeared. Then, upon irradiation of appropriate visible light (λ > 500 nm), the colored PMMA film can back to colorless. From the above description, we can easily get a conclusion that both open-ring isomer and closed-ring isomer of this diarylethene were stable in solution at room temperature in darkness. 24 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 38. 300 400 500 600 0.00 0.25 0.50 0.75 Absorbance Wavelength/nm Vis UV Vis UV Vis UV 300 400 500 600 700 0.0 0.5 1.0 1.5 Absorbance Wavelength/nm Vis UV Vis UV Fig. 1 Absorption spectra upon alternating irradiation with UV-Vis light of the compound 1o in hexane (2.0 × 10-5 mol/L). Photochromic reaction kinetics in hexane solution. The photochromic cyclization and cycloreversion kinetics of this diarylethene in hexane were determined by UV-Vis spectra upon alternating irradiation with appropriate wavelength UV and visible light at room temperature. The cyclization and cycloreversion curves of compound 1o were shown in Fig.2 (A), respectively. It can be seen that the relationships between the absorbance and exposal time have good linearity upon irradiation with 297 nm UV light. It is suggesting that the cyclization processes of compound 1o belong to the zeroth order reactio when open-ring isomers changed to closed-ring isomers. At the same time, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also behave perfect linearity, as shown in Fig.2 (B), indicating that the cycloreversion process belong to the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3 ) of diarylethene 1c can be easily obtained in solution, respectively. 0 8 16 24 32 40 0.01 0.02 0.03 0.04 0.05 0.06 Absorbance Time/s A Y=A+B*X A=0.0058 B=0.0013 R=0.9991 0 8 16 24 32 40 1.40 1.75 2.10 2.45 2.80 -log(Abs) Time/s B Y=A+B*X A=1.090 B=0.039 R=0.991 Fig. 2 The cyclization (A) and cycloreversion (B) kinetics of compound 1o in hexane. Polarization Recording Properties. With a He-Ne laser (wavelength: 650 nm, 105 mW) in the experimental setup, the evaluation of potential of photochromic diarylethene as a polarization medium by recording and reading in a real-time operation was investigated. Using diarylethene 1/PMMA film as recording medium, the polarization patterns were recorded and read on the film under the microscope as shown in Fig. 3. The result indicated that the new photochromic diarylethene can be applied in high capacity optical storage [12]. Fig. 3 Experimental setup for writing and reading polarization spot patterns. Advanced Materials Research Vol. 1003 25
- 39. Summary A novel unsymmetrical diarylethene was synthesized to investigate its photochromism, kinetic and fluorescence. Diarylethene 1o exhibited photochromism in hexane solution. The present results are useful for the design of efficient photoactive and excellent characteristic diarylethene compounds. Furthermore, the compound also functioned as a fluorescence switch. Acknowledgment The authors are grateful for the financial support from the National Natural Science Foundation of China (21363009). References [1] W. Feng, K. Huang and M.X. Wang: Chin. Phys. Vol. 14 (2005), p. 306 [2] G. Berkovic, V. Krongauz and V. Weiss: Chem. Rev. Vol. 100 (2000), p. 1741 [3] Y.C. Liang, A.S. Dvornikov and P.M. Rentzepis: Macromolecules Vol. 35 (2002), p. 9377 [4] J. Yin, X. Cao, F. Yu, G.A. and S.H. Liu: Tetrahedron Lett. Vol. 49 (2008), p. 1582 [5] G. M. Tsivgoulis and J.M. Lehn: Angew. Chem. Int. Ed. Vol. 34 (1995), p. 1119 [6] M. Iire: Chem. Rev. Vol. 100 (2000), p. 1685 [7] H. Tian and S. J.Yang: Chem. Soc. Rev. Vol. 33 (2004), p. 85 [8] K. Higashiguchi, K. Matsuda, N. Tanifuji and M. Irie: J. Am. Chem. Soc. Vol. 127 (2005), p. 8922 [9] M Irie, O Miyatake, K Uchida and T Eriguchi: J. Am. Chem. Soc. Vol. 116 (1994), p. 9894 [10]K Uchida, T Ishikawa, M Takeshita and Irie M: Tetrahedron Vol. 54 (1998), p. 6627 [11]S.Z. Pu, G. Liu, L. Shen, and J.K. Xu: Organic Letters Vol. 9 (2007), p. 2139 [12]S.Z. Pu, H.H. Tang, B. Chen, J.K. Xu, W.H. Huang: Mater. Lett. Vol. 60 (2006), p. 3553 26 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 40. Research on Photochromic Materials with Synthesis and Properties of 1-(3,5-Dimethyl-4-isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl] perfluorocyclopentene Guanming Liao, Dandan Xue, Chunhong Zheng* and Shouzhi Pu Jiangxi Key Lab of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, China zch722108@126.com Keywords: Diarylethene; Photochromism; Isoxazole moiety; Fluorescence; Kinetic Abstract. An asymmetrical photochromic diarylethene 1-(3,5-Dimethyl-4-isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene(1o) was synthesized and its photochromic properties were investigated. Upon irradiation with 297 nm UV light, 1o exhibited photochromism in hexane solution. The kinetic experiments showed that the cyclization and cycloreversion processes were zeroth and first order reaction, respectively. Moreover, diarylethene 1o also exhibited obviously fluorescence switches along with the photochromism. Introduction Photochromic materials have attracted a great deal of interest due to their potential application in optical memories and switching devices [1,2]. Up to date, many types of photochromic compounds have been reported. Among them, diarylethenes are one of the most promising candidates for photoelectronic applications owing to their excellent thermal stability and fatigue resistance [3]. Perfluorodiarylethenes are well known as one of the most popular class of photochromic diarylethenes [1]. Their photochromic properties depend on several factors, such as conformation of the open-ring isomer [4], nature of heteroarylmoieties [1], and electronic properties of substitutes [5]. Particularly, the nature of heteroaryl moieties mainly dictates the properties of photochromic systems. Upon recent reports [6-8],the isoxazole moiety induced some new features differing from diarylethenes with other heteroaryl moieties reported. As described above, herein, a novel unsymmetrical diarylethene1-(3,5-Dimethyl-4- isoxazolyl)-2-[2-methyl-5-(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene (1o) was designed and synthesized. Diarylethene 1o showed notable photochromism in hexane solution. The schematic illustration of photochromism is shown in Scheme 1. Scheme 1. Photochromism of diarylethene 1o. Advanced Materials Research Vol. 1003 (2014) pp 27-30 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.27
- 41. Experiments Synthesis of diarylethene 1o. The synthesis route for diarylethene 1o is shown in Scheme 2. According to the similar procedure [9], diarylethene 1o was synthesized visible as a light yellow with a 56% yield. 1 H NMR (400 MHz, CDCl3,): δ 1.36 (t, 3H,-CH3), 1.95 (d, 6H, J = 8.0 Hz,-CH3), 3.84 (s, 3H, -CH3), 3.96–3.98 (m, 2H, -CH2), 6.83 (d, 2H, J = 8.0 Hz, benzene-H), 7.02 (s, 1H, thiophene-H), 7.36 (d, 2H, J = 8.0 Hz, benzene-H). Scheme 2. Synthetic route for the diarylethene 1o. Results and discussion Photochromism of diarylethene 1o. The photoisomerization of ring-open isomer 1o and ring-closed isomer 1c with UV/vis light irradiation was illustrated in Scheme 1.The absorption bands of 1o in hexane (2.0 × 10-5 mol L-1 ) appeared at 286 nm (2.3 × 104 L mol-1 cm-1 ). Upon irradiation with 297 nm light, the colorless solution of 1o was converted into a purple solution of 1c with an absorption band at 533 nm, and 1c could be bleached completely back to 1o with visible light ( λ > 510 nm), resulted in the color change of the solution from purple to colorless. As shown in Fig. 1, it showed the typical absorption spectra changes of diarylethene derivatives in solution and it could also be seen clearly that an isosbestic point appeared in the absorption spectra changes of photocyclization, indicating only two isomers existed when 1o underwent the photoisomerization reaction. 300 400 500 600 700 0.0 0.1 0.2 0.3 0.4 Absorbance Wavelength/nm Vis UV Vis UV Fig. 1. Absorption spectral and color change of 1o by photoirradiation in hexane (2.0 × 10-5 mol L-1 ). Photochromic reaction kinetics in hexane solution. The photochromic cyclization/cycloreversion kinetics of 1o in hexane were determined by UV-Vis spectra upon alternating irradiation with UV and appropriate wavelength visible light at room temperature. The cyclization and cycloreversion curves of 1o were shown in Fig. 2. It can be seen that the relationships between the absorbance and exposal time have good linearity upon irradiation with 297 nm UV light. It is demonstrating that the cyclization processes of 1o belong to the zeroth order reaction when open-ring isomer changed to closed-ring isomer. The slope of every line in Figs. 2(A) and 2(B) represents the reaction rate constant (k) of diarylethene 1o in hexane. So all k of cyclization (ko-c, 10-3 ) / cycloreversion (kc-o, 10-2 ) process of diarylethene 1o can be easily obtained, which are 1.40 mol L-1 s-1 and 7.80 s-1 in solution, respectively. As shown in Fig. 2(B), during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also behave perfect linearity, indicating that the cycloreversion process belong to the first order reaction. 28 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 42. Fluorescence of diarylethene 1o. Fig. 3(A) shows the concentration dependence of fluorescence emission spectra of 1o in hexane at room temperature, and the breadths of excitation and emission slit were selected 5.0 nm and 5.0 nm, respectively. When the concentration of 1o in hexane increased from 1.0 × 10-6 mol L-1 to 5.0 × 10-4 mol L-1 , the maximum emission arose from 451 to 453 nm when excited at 299 nm and the fluorescence intensity increased with increasing concentration, especially, when the concentration increased from 2.0 × 10-5 mol L-1 to 5.0 × 10-5 mol L-1 , the relative fluorescence intensity increased remarkably, but when the concentration increased enough high, the fluorescence intensity decreased rapidly. This self-quench phenomenon maybe resulted from the formation of excimers and of exciplexes in high concentration solutions so that deactivation effect can occur during the excited-state lifetime [10]. 0 8 16 24 32 40 0.000 0.012 0.024 0.036 0.048 0.060 Absorbance Time (s) Y = 0.00618 + 0.00143 * X R=0.99482 (A) 0 5 10 15 20 25 0.8 1.2 1.6 2.0 2.4 2.8 -log(Abs) Time(s) Y = 0.73704 + 0.07819 * X R=0.99168 (B) Fig. 2. The kinetics of diarylethene 1o in hexane: (A) cyclization; (B) cycloreversion. The fluorescence emission spectra of diarylethene 1o in hexane (2.0 × 10-5 mol L-1 ) was evaluated at room temperature, and the result is shown in Fig. 3(B).The emission peak of 1o in hexane was observed at 453 nm when excited at 299 nm. Typically, the fluorescence of diarylethene could be reversibly modulated by photoirradiation during the process of photoisomerization [11-12]. Upon irradiation with 297 nm light, the emission intensity of 1o was notably decreased in hexane solution due to the formation of the weak fluorescent closed-ring isomer 1c. The back irradiation by appropriate visible light regenerated the open-ring isomer 1o and recovered the original emission intensity. As shown in Fig. 3, the emission intensity of 1o was quenched to ca. 73% in hexane in the photostationary state. That is to say, the fluorescent modulation efficiency of 1o was 27% in hexane. 400 450 500 550 0 100 200 300 400 1x10-6 mol L-1 2x10-6 mol L-1 5x10-6 mol L-1 1x10-5 mol L-1 2x10-5 mol L-1 5x10-5 mol L-1 1x10-4 mol L-1 2x10-4 mol L-1 5x10-4 mol L-1 Emission Intensity (a.u.) Wavelength (nm) (A) 400 450 500 550 0 150 300 450 Emission Intensity (a.u.) Wavelength (nm) Vis UV (B) Fig.3. (A) Fluorescence spectra of diarylethenke 1o in various concentrations in hexane excited at 299 nm at room temperature.(B)Emission intensity changes of diarylethene 1o upon irradiation with 297 nm UV light at room temperature in hexane (5.0 × 10-5 mol L-1 ). Summary In summary, a novel diarylethene with isoxazole moiety has been synthesized. It showed good photochromic behavior in hexane solution. Our experimental results showed that the cyclization process of 1o belongs to the zeroth order reaction and the cycloreversion process belongs to the first Advanced Materials Research Vol. 1003 29
- 43. order reaction, respectively. The fluorescence of the diarylethene 1o could also be reversibly modulated by photoirradiation. Acknowledgement The authors are grateful for the financial support from the National Natural Science Foundation of China (21362013, 51373072). References [1] M. Irie: Chem. Rev. Vol. 100 (2000), p. 1685 [2] H.H. Liu and Y. Chen: Dyes Pigm. Vol. 89 (2011), p. 212 [3] M. Morimoto, S. Kobatake and M. Irie: J. Am. Chem. Soc. Vol. 125 (2003), p. 11080 [4] M. Irie, O. Miyatake, K. Uchida and T. Eriguchi: J. Am. Chem. Soc. Vol. 116 (1994), p. 9894 [5] S.Z. Pu, C.H. Zheng, Z.G. Le, G. Liu and C.B. Fan: Tetrahedron. Vol. 64 (2008), p. 2576 [6] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron.Vol. 67 (2011), p. 1447 [7] G. Liu, M. Liu, S.Z. Pu, C.B. Fan and S.Q. Cui: Tetrahedron.Vol. 68 (2012), p. 2267 [8] S.Z. Pu, Z.P. Tong, G. Liu and R.J. Wang. J: Mater. Chem. C. Vol. 1 (2013), p. 4726 [9] S.Z. Pu, G. Liu and J.K. Xu: Org. Lett. Vol. 9 (2007), p. 2139 [10]T. Fukaminato, T. Kawai, S. Kobatake and M. Irie: J. Phys. Chem. B. Vol. 107 (2003), p. 8372 [11]H. Tian, B.Z. Chen, H.Y. Tu and K.Müllen: Adv. Mater. Vol. 14 (2002), p. 918 [12]S.Z. Xiao, T. Yi, Y.F. Zhou, Q. Zhao, F.Y. Li and C.H. Huang: Tetrahedron. Vol. 62 (2006), p. 10072 30 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 44. Synthesis and Properties Study of 1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thieny l]perfluorocyclopentene Jingjing Liu, Hongjing Jia and Shouzhi Pu* Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University Nanchang 330013, P.R.China pushouzhi@tsinghua.org.cn Keywords: Diarylethene, Photochromism, Pyrimidine, Fluorescence. Abstract. A novel photochromic diarylethene bearing a pyrimidine moiety, 1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thienyl]perfluorocyclopentene has been synthesized. Its properties, including photochromic behavior and fluorescent properties, have been investigated. The compound exhibited remarkable photochromism, changing from colorless to red after irradiation with UV light in solution. The fluorescence had a remarkable initial increase with subsequent dramatic decrease with increasing concentration. The results indicated that the pyrimidine moiety played a very important role during the process of photoisomerization reactions. Introduction Photochromic diarylethenes undergo reversible photoisomerization between two isomers with different absorption spectra upon irradiation with light of appropriate wavelength [1]. Photochromic molecules have been attracted much attention from both fundamental as well as practical points of view because of their potential applications for optical devices, such as optical memories and switches [2-4]. Among the various types of photochromic compounds, diarylethenes are regarded as the most promising candidates, because diarylethene derivatives have excellent thermal stability of the respective isomers, notable fatigue resistance, rapid response, and high reactivity in solid state. Diarylethene with heterocyclic aryl rings are the most promising candidates for photoelectronic applications among various types of photochromic compounds [5-7]. In the past several decades, numerous studies have focused on molecular design, especially the synthesis of symmetrical and asymmetrical frameworks in diarylethenes with different heteroaryl units. For example, the diarylethenes having two thiophenes [8], furans [9] and thiazoles [10-12] exhibit excellent thermal stability, and the ones with two indoles, pyrrols, and benzenes are thermally unstable [12,13]. Nevertheless, the hexatriene backbones necessary for the versatility of the diarylethenes reported so far have been mostly limited to the five-membered aryl rings. Up to date, the reports about diarylethenes with six-membered pyrimidine rings are still very rare. In this work, we synthesized a new diarylethene bearing a pyrimidine moiety, namely 1-(2,4-dimethoxyl-5-pyrimidinyl)-2-[2-methyl-5-(9-phenanthrene)-3-thienyl]perfluorocyclopentene (1o). Its photochromic reactivity and fluorescence were investigated in detail. The photochromic reaction of diarylethene 1 is shown in Scheme 1. F F F F F F S F F F F F F S UV Vis 1c N N O O N N O O 1o Scheme 1. Photochromism of diarylethene 1. Advanced Materials Research Vol. 1003 (2014) pp 31-34 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.31
- 45. Experiments The synthetic route for the diarylethene 1 is shown in Scheme 2. Suzuki coupling of the 9-bromophenanthrene with a thiophene boronic acid 2 gave the compound 3. Then, compound 3 was lithiated and coupled with perfluorocyclopentene to give mono-substituted perfluorocyclopentene derivative 4. Finally, 5-bromo-2,4-dimethoxypyrimidine was lithiated and then coupled with compound 4 to give the unsymmetrical diarylethene derivative 1o. The structure of diarylethene 1o was confirmed by 1 H NMR (400 MHz, CDCl3, TMS): δ 2.13 (s, 3H, -CH3), 3.78 (s, 3H, -OCH3), 3.98 (s, 3H, -OCH3), 7.02 (s, 1H, thiophene-H), 7.51-7.65 (m, 4H, benzene-H), 7.71 (s, 1H, benzene-H), 7.81 (d, 1H, J = 8.0 Hz, benzene-H), 8.07 (d, 1H, J = 8.0 Hz, benzene-H), 8.32 (s, 1H, pyrimidine-H), 8.61 (d, 1H, J = 8.0 Hz, benzene-H), 8.63 (d, 1H, J = 8.0 Hz, benzene-H). S S Br B(OH)2 Pd(PPh3)4 NaCO3,aq. Br n-BuLi, 195K C5F8 2 F F F F F F F S n-BuLi, 195K 3 4 N N O O Br F F F F F F S N N O O 1o Br Scheme 2. Synthetic route for the compound 1o. Results and Discussion Photochromism of Diarylethene. The changes in the absorption spectra of diarylethene 1o induced by photoirradiation at room temperature in hexane were shown in Figure 1. Upon irradiation with 297 nm UV light, the colorless solution of 1o turned to red with a new visible absorption band centered at 515 nm (ε = 3.5 × 103 L mol-1 cm-1 ) attributable to the closed-ring isomer 1c. The red colored solution reverted to colorless upon irradiation with visible light (λ > 450 nm), indicating that 1c returned to the initial state 1o, and a clear isosbestic point was observed at 330 nm. Figure 1. Absorption spectra and color change of diarylethene 1o with stimulation of 297 nm light in hexane (2.0 × 10-5 mol L-1 ) at room temperature. Fluorescence of Diarylethene. Fluorescent properties can be useful in molecular scale optoelectronics, but for digital photoswitching of fluorescence. In our present work, the fluorescence properties of the compound 1 in both the solution (c = 1.0 × 10-4 mol L-1 ) and PMMA film(10%w/w) were measured using a Hitachi F-4600 spectrophotometer, and the breadths of emission slit were selected 5.0 nm and 5.0 nm. As shown in Figure 2, the fluorescence intensity of diarylethene 1o 32 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 46. decreased dramatically upon irradiation with 297 nm light, with the photochromism from open-ring isomer to closed-ring isomer. The emission intensity of diarylethene 1c in a photostationary state was quenched to ca. 39.9% in hexane and ca. 84.1% in PMMA film. The cyclization reaction which is not complete and the existence of parallel conformations may be the main cause for the moderate change in fluorescence induced by photoirradiation. The reversible changes of the emission intensity of diarylethene 1 are useful for application as the fluorescence switches [14,15]. Figure 2 Fluorescence spectral changes of compound 1 in hexane (1.0 × 10-4 mol/L) (A) and in PMMA (10%, w/w) (B) with 297 nm UV light. The concentration dependence on the fluorescence spectrum of diarylethene 1o was measured in hexane at room temperature, as shown in Figure. 3. When the concentration of diarylethene 1o in hexane was increased from 1.0 × 10-6 mol/L to 1.0 × 10-4 mol/L, the maximum emission almost arose at 434 nm when excited at 345 nm, and the relative fluorescence intensity increased dramatically. However, when the concentration increased from 1.0 × 10-4 to 5.0 × 10-4 mol/L, the relative fluorescence intensity decreased remarkably. The hexane solution showed very weak fluorescence when the concentration was increased to 5.0 × 10-4 mol/L. The results showed that the fluorescence of the compound was remarkably concentration dependent. The results also demonstrated that molecular aggregation and the fluorescence quenching may occur when the concentration increases [16]. Figure 3. Fluorescence of diarylethene 1o in various concentrations in hexane excited at 345 nm. Summary An unsymmetrical diarylethene with a pyrimidine unit was synthesized to investigate its photochromism and fluorescence properties. The results showed that diarylethene 1o showed excellent photochromism in solution. In addition, the diarylethene 1o also exhibited relatively strong fluorescence in hexane solvent and in PMMA film. Its fluorescence had a remarkable initial increase with subsequent dramatic decrease with increasing concentration. Advanced Materials Research Vol. 1003 33
- 47. Acknowledgment The authors are grateful for the financial support from the National Natural Science Foundation of China (21362013, 51373072). References [1] S. Kobatake and M. Irie: Chem. Lett. Vol. 32 (2003), p. 1078 [2] Y. Chen, C.M. Wang, M.G. Fan, B.L. Yao and N. Menke: Opt. Mater. Vol. 26 (2005), p. 75 [3] T. Fukaminato, T. Sasaki, T. Kawai, N. Tamai and M. Irie: J. Am. Chem. Soc. Vol. 126 (2004), p.14843 [4] S.Z. Pu, F.S. Zhang, J.K. Xu, L. Shen, Q. Xiao and B. Chen: Mater. Lett. Vol. 60 (2006), p. 485 [5] M. Irie: Chem. Rev. Vol. 100 (2000), p. 1685 [6] K. Matsuda and M. Irie: J. Photoch. Photobiol. C. Vol. 5 (2004), p. 169 [7] M. Morimoto and M. Irie: Chem. Commun. Vol. 36 (2006), p. 3895 [8] H. Tian and S.J. Yang: Chem. Soc. Rev. Vol. 33 (2004), p. 85 [9] X.D. Deng and L.S. Liebeskind: J. Am. Chem. Soc. Vol. 123 (2001), p. 7703 [10] K. Uchida, T. shikawa, M. Takeshita and M. Irie: Tetrahedron Vol. 54 (1998), p. 6627 [11] S. Takami and M. Irie: Tetrahedron Vol. 60 (2004), p. 6155 [12] S.Z. Pu, H. Li, G. Liu and W.J. Liu: Tetrahedron Lett. Vol. 5 (2010), p. 3575 [13] K. Uchida, T. Matsuoka, K. Sayo, M. Iwamoto, S. Hayashi and M. Irie: Chem. Lett. Vol. 8 (1999), p. 835 [14] B. Chen, M. Wang, Y. Wu and H. Tian: Chem. Commun. Vol. 21 (2002), p. 1060 [15] H. Tian, B.Z. Chen, H.Y. Tu and K. Müllen: Adv. Mater. Vol. 17 (2002), p. 918 [16]T. Fukaminato, T. Kawai, S. Kobatake and M. Irie: J. Phys. Chem. B. Vol. 107 (2003), p. 8372 34 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 48. Research on Photochromic Materials with Synthesis and Application of 1-(2-methyl-3-benzothienyl)-2-[2-methyl-(5-ethynyl) trimethylsilane-3-thienyl] Perfluorocyclopentene Lele Ma, Hongyan Xu and Gang Liu* Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, P.R.China liugang0926@163.com Keywords: Photochromism; Fluorescence; Kinetics; Diarylethene. Abstract. A new unsymmetrical photochromic diarylethene compound, 1-(2-methyl-3-benzothienyl)-2- (2-methyl- (5-ethynyl)trimethylsilane-3-thienyl) perfluorocyclopentene (1o) has been synthesized, and its optoelectronic properties, such as photochromism and the fluorescence spectra of diarylethene 1o in hexane solution was investigated. The results showed that this compound exhibited reversible photochromism in solution. The maxima absorption of compound closed-ring isomer 1c are 538 nm. Its fluorescence intensity decreased along with the photochromism from open-ring isomers to closed-ring isomers upon irradiation with 297 nm UV light. Introduction Photochromic materials have been extensively investigated because of their potential application to photonic devices, such as high-density optical recording materials and photoswitches [1-3] and full-color display devices [4,5]. During the past decades, the majority of the study work reported has been devoted to the development of these molecules and investigative studies of their fundamental properties. In those literatures, diarylethene derivatives with heterocyclic aryl rings are the most promising organic photochromic compounds for photoelectronic applications because of the excellent thermal stability of both of the two isomers, fatigue resistant character, rapid response and high reactivity in solid state [6,7]. Recently, we have been reported some new classes of photochromic diarylethene derivatives [8-10]. In the present study, we designed a red photochromic diarylethene compound, 1-(2-methyl-3-benzothienyl)-2-(2-methyl-(5-ethynyl)trimethylsilane-3-thienyl) perfluorocyclopentene (1o). The photochromic reaction of diarylethene 1o is shown in Scheme 1. Scheme 1. Photochromism of diarylethenes 1 Experiments. Synthesis of diarylethene 1o. The synthetic route for the diarylethene 1o was described in according to the method described in Scheme 2. The structure of compound 1o was confirmed by 1 H NMR. NMR spectra were recorded on Bruker AV400 (400 MHz) spectrometer with CDCl3 as the solvent and tetramethylsilane as an internal standard. 1 H NMR (400 MHz, CDCl3), δ (ppm): 0.15 (s, 9H), 1.73 (s, 3H), 2.18 (s, 3H), 7.12 (s, 1H),7.22-7.27 (m, 2H), 7.45 (d, 1H, J = 8.0Hz), 7.63 (d, 1H, J = 8.0Hz). Advanced Materials Research Vol. 1003 (2014) pp 35-38 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.35
- 49. Scheme 2. Synthetic route to diarylethene 1o Results and Discussion Photochromism in solution. The changes of diarylethene 1o in the absorption spectra induced by photo-irradiation at room temperature in hexane solution are shown in Fig. 1. The absorption show spectral changes of diarylethene 1o in hexane(Fig. 1A) (2.0 × 10-5 mol/L) and in PMMA film(Fig. 1B) (10% w/w) by photoirradiation, respectively. Upon irradiation with 297 nm light, the color of the solution turned red, in which the absorption maximum was observed at 538 nm. Reversely, the red solution turned colorless by irradiation with visible light (λ > 500 nm), indicating that 1c returned to the initial state 1o and a clear isosbestic point was observed at 259 nm. The significant difference in absorption bands of the closed-ring isomer compared to its open-ring isomer is mainly due to the increase in π conjugation, which dramatically changes the electronic structure as a whole in such a way that new electronic transitions are observed in the visible region [11,12]. Fig.1 Absorption spectra changes of 1o in hexane (A) and in PMMA (B) Photochromic Reaction Kinetics in Hexane Solution. The photochromic cyclization and cycloreversion kinetics of this diarylethene in hexane were determined by UV-Vis spectra upon alternating irradiation with appropriate wavelength UV and visible light at room temperature. The cyclization and cycloreversion curves of 1o were shown in Fig. 2(A) and Fig. 2(B), respectively. It can be seen that the relationships between the absorbance and exposal time have good linearity upon irradiation with 297 nm UV light. The slope of line in Fig. 2(A) and Fig. 2(B) represents the reaction rate constant (k) of 1o in hexane. It is suggesting that the cyclization processes of compound 1o belong to the zeroth order reaction when open-ring isomers changed to closed-ring isomers. At the same time, during the cycloreversion of 1c, the relationship between –log(Abs) and exposal time also behave perfect linearity, as shown in Fig. 2(B), indicating that the cycloreversion process belong to the first order reaction. So all k of cyclization/cycloreversion process (ko-c, 10-3 ) of diarylethene 1c can be easily obtained in solution, respectively. 36 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 50. Fig. 2 The cyclization (A) and cycloreversion (B) kinetics of 1o in hexane. Fluorescence of diarylethene. Fluorescent properties can be not only use in molecularscale optoelectronics, but also for digital photoswitching of fluorescence. In this work, the fluorescence properties of the diarylethene in both solution (2.0 × 10-5 mol/L) and PMMA film (10% w/w) were measured using a Hitachi F-4600 spectrophotometer. Upon irradiation with UV light, the fluorescence of 1 effectively decreased along with photocyclization due to the production of the non-fluorescence closed-ring isomer 1. Fig. 3 Fluorescence spectral changes of compound 1 in hexane (2.0 × 10P -5 mol/L) (A) and in PMMA (10%, w/w) (B) with 297 nm UV light. Summary A new unsymmetrical photochromic diarylethene was synthesized. Its photochromic properties and fluorescent properties were investigated. The results showed that this compound exhibited reversible photochromism in solution and in PMMA film. The results will be helpful to the synthesis of photoactive diarylethene derivatives with new molecular skeletons and to design new photochromic systems for further potential applications. Acknowledgment The authors are grateful for the financial support from the National Natural Science Foundation of China (21262015). Advanced Materials Research Vol. 1003 37
- 51. References [1] Y. Chen, D. X. Zeng, N. Xie: J. Org. Chem. Vol. 70(2004), p. 5001 [2] T. Fukaminato, T. Sasaki, and M. Irie : J. Am. Chem. Soc, Vol.126, p.14843 [3] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu: Dyes and Pigments Vol. 90 (2011), p. 71 [4] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui: Tetrahedron Vol. 67 (2011), p. 1438 [5] G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980 [6] K. Matsuda, M. Irie, J. Photochem. Photobiol. C: Photoch. Vol. 5 (2004), p.169. [7] H. Tian: Angew. Chem. Int. Ed. Vol. 49 (2010), p.4710 [8] G. Liu, S.Z. Pu, X.M. Wang, W.J. Liu and T.S. Yang: Dyes and Pigments Vol. 90 (2011), p. 71 [9] S.Z. Pu, H. Li, G. Liu, W.J. Liu, S.Q. Cui and C.B. Fan: Tetrahedron Vol. 67 (2011), p. 1438 [10]G. Liu, S.Z. Pu and R.J. Wang: Org. Lett. Vol. 15 (2013), p. 980 [11]S.Z. Pu, C.H. Zheng, Z.G. Le, G. Liu and C.B. Fang: Tetrahedron Vol. 64 (2008), p. 2576 [12]Z. X. Li, L. Y. Liao, W. Sun, C. H. Xu, C. Zhang, C. J. Fang and C. H. Yan: J. Phys. Chem. Vol. 112 (2008), p. 5190 38 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 52. Research on Photochromic Compounds with Efficient Synthesis and Photochromic Properties of 1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-pentylphenyl)-3-thienyl] perfluorocyclopentene Junjie Song and Gang Liu* Jiangxi Key Lab of Organic Chemistry, Jiangxi Science and Technology Normal University Nanchang 330013, China liugang0926@163.com Keywords: Phenyl; Diarylethene; Photochromism; Fluorescence Abstract. A novel isomeric photochromic diarylethene, 1-(2-methyl-5-phenyl-3-thienyl)- 2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]perfluorocyclopentene, was designed and synthesized. Its fluorescent and photochromic properties were also studied in detail. The compound exhibited excellent photochromism, changing from colorless to bule after irradiation with UV light both in solution and in PMMA film. In addition, the fluorescence intensity of the photochromic diarylethene 1a declined remarkably, when irradiation with UV light. Introduction Photochromic compounds have been extensively designed and synthesized for their potential applications in erasable optical memories, displays, and optical switches [1-3]. Thus, further creation of optoelectronic and photo-optical devices based on photochromic molecular switches which operate at both molecular and supramolecular levels have recently attracted many attentions [4]. Photochromic is referred to as a photoisomerization process between two isomers having different absorption spectra [5]. Among the various types of photochromic compounds, diarylethenes are regarded as the most promising candidates, because of diarylethene derivatives have excellent thermal stability of the respective isomers, notable fatigue resistance, and rapid response, and high reactivity in solid state, diarylethene with heterocyclic aryl rings are the most promising candidates for photoelectronic applications among various types of photochromic compounds [6-8]. F F F F F F S S F F F F F F S S UV vis 1a 1b Scheme 1. Photochromism of dithienylethene 1a. Up to now, a large number of publications concerning about diarylethene derivatives with different aryl moieties, such as thiazole [9,10,11], indole [12], benzofuran [13], crysothiophene [14], pyrrole [15] and indene [16], etc, have been reported. Among these novle photochromic diarylethenes, there are few examples of photochromic diarylethenes bearing phenanthrene rings. The results highly encourage us to develop a new class of hybrid photochromic diarylethene derivatives bearing an phenanthrene moiety. In this paper, we designed and synthesized a new diarylethene bearing phenanthrene unit and fused ring units, namely 1-(2-methyl-5-phenyl-3-thienyl) -2-[2-methyl-5-(4-pentylphenyl)-3-thienyl]perfluorocyclopentene (1a). Its photochromic reactivity, fluorescence were investigated in detail. The photochromic reaction of diarylethene 1a is shown in Scheme 1. Advanced Materials Research Vol. 1003 (2014) pp 39-42 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1003.39
- 53. Experiments The synthetic route for the diarylethene 1a is shown in Scheme 2. Suzuki coupling of the bromobenzene derivative with a thiophene boronic acid 2 gave the compound 3. Under an argon gas atmosphere, compound 4 was dissolved in THF and n-Butyl lithium hexane solution was added at 195 K. Stirring was continued for 30 min at this low temperature, octafluorocyclopentene was added and the mixture was stirred for 2 h at this temperature. Then compound 5 was yield. Compound 1a was prepared by reacting compound 3 with compound 5 in dry THF at 195 K. After extracting with diethyl ether and evaporation in vacuo, the residue was purified by column chromatography on silica gel to give 1a. The structures of diarylethenes 1a were confirmed by 1 H NMR (400 MHz, CDCl3, TMS): δ 0.80-0.91 (m, 3H), 1.16-1.25 (m, 4H), 1.35-1.54 (m, 2H), 2.35-2.37 (t, 6H),2.54-2.67 (m, 2H) 7.01-7.18 (d, 2H), 7.21-7.24 (d, 1H), 7.26-7.43 (d, 2H), 7.46-7.52 (t, 2H), 7.71-7.74 (d, 4H) F F F F F F n-BuLi/THF C5F8, S Br S Br B(OH)2 Br Pd(PPh3)4,Na2CO3,aq n-BuLi/THF 195K 195K 1a F 2 3 4 5 S Br S F F F F F F S S Scheme 2. Synthetic route for the compound 1a. Results and Discussion Photochromism of diarylethene. The unsymmetrical diarylethene 1a exhibits good photochromic properties and can be toggled between its colorless ring-open and colored ring-closed forms by alternate irradiation with appropriate wavelengths of light. The absorption spectral changes in hexane are shown in Fig. 1. The open ring isomer has an absorption maximum at 280 which was arisen from π→π* transition. Upon irradiation with 297 nm UV light, the colorless hexane solution of compound 1a turned blue, in which absorption maximum was observed at 571 nm. The blue color is due to the formation of the closed ring isomer. When blue solution was irradiated with visible light (λ > 450 nm), the blue color could return back to colorless and its spectrum became the same as that of original one, indicating compound 1a returned to the initial open ring isomer. The coloration/discoloration cycle could be repeated more than 50 times and the photostationary spectrum was almost the same as that of the colored isomer. This indicates a high conversion from the colorless to the colored isomers by irradiation with 297 nm light. In order to practical applications in optical devices for the future, it is extremely important that photochromic materials can keep excellent photochromic in a polymer film, such as the PMMA film. Dissolved ultrasonically 5 mg diarylethene sample and 50 mg PMMA into 0.5 mL chloroform, the film was prepared by spin-coating method. In PMMA amorphous film, diarylethene 1a also showed good photochromic (Fig. 1b) as similar to that in solution. Upon irradiation with 297 nm light, the colorless diarylethene 1a /PMMA film turned blue for which the absorption maxima were observed at 584 nm, as the closed-ring isomer 1b was generated. The colored diarylethene /PMMA films can revert to colorless upon irradiation with visible light (λ > 450 nm). The color changes of diarylethene upon photoirradiation in hexane and in PMMA are also shown in Fig. 1a and Fig. 1b respectively. The maximum absorption peaks of both the open-ring and the closed-ring isomers in PMMA film are longer than those in hexane solution. The red shift phenomenon is consistent with those of the majority of the reported diarylethenes [17]. 40 Advanced Research on Material Engineering, Electrical Engineering and Applied Technology II
- 54. Fig. 1 Absorption spectral and color changes of compound 1 in hexane (2.0 × 10-5 mol L-1 ) (a) and in PMMA film (10%, w/w) (b). Fluorescent of diarylethene. Fluorescent properties can be useful not only in molecularscale optoelectronics, but for digital photoswitching of fluorescence. In this work, the fluorescence properties of the diarylethene both in solution and in PMMA film(10% w/w) were measured using a Hitachi F-4600 spectrophotometer. The result showed that 1a exhibited good fluorescence both in hexane solution and in PMMA film, and the emission peaks are 393 and 472 nm , respectively. The fluorescence intensity of diarylethene 1a decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm light. As shown in Figure 2, when irradiated by light of 297 nm, the photocyclization reaction was carried out and the non-fluorescent closed-ring form of the compound were produced. The back irradiation by appropriate wavelength visible light regenerated the open-ring forms of diarylethene 1a and recovered the original emission spectra. The emission intensity of diarylethene 1a in a photostationary state was quenched to ca. 15% in hexane and ca. 33% in PMMA film. The incomplete cyclization reaction and the existence of parallel conformations may be the main cause for the moderate change in fluorescence induced by photoirradiation. The reversible changes of the emission intensity of diarylethene 1a are useful for application as the fluorescence switches [18,19]. Fig. 2 Fluorescence spectral changes of compound 1 in hexane(2.0 × 10-5 mol L-1 ) (a) and in PMMA (b) with 297 nm UV light. Summary In conclusion, a new diarylethene derivative, which is described here with good photochromic properties both in solution and in PMMA amorphous film, has been synthesized. Furthermore, it has also been demonstrated that both the open ring and closed ring isomers of the diarylethene compounds exhibit strong fluorescence, and their maximum emission wavelengths were observed at 393 nm when excited at 318 nm. The results illustrated that the diarylethene 1a had attractive properties for polarization holographic optical recording. Such diarylethene derivatives have been expected to have wide application in optical data storage and retrieval, rewritable optical memory and display, various sensors and switches, etc. Advanced Materials Research Vol. 1003 41
- 55. Another Random Document on Scribd Without Any Related Topics
- 56. Chapter Twenty Five. One Sunday Morning. The Rector of a large West-end church was ill. His illness was not very serious, nor did it threaten to be protracted, but it fell at a bad moment. It was the middle of the season, the time at which his church was more crowded than at any other of the year. He was an earnest and thoughtful man, and one who, despite much discouragement, laboured energetically to do his best; but on the Friday evening, preceding the second Sunday in June, he was obliged to acknowledge that for some days he would be unfit to officiate in his usual place. “What shall I do?” he said in distress. “What shall I do about the sermon on Sunday morning? The curates can manage the rest, but it will be as much as they can do. I cannot ask either of them to prepare another sermon so hurriedly. And the one I had ready has cost me much time and thought—I had even built some hopes upon it. One never knows—” “Your sermon will keep till another Sunday. That is not the question,” said his wife. “No, truly,” he agreed, with some bitterness; “my sermon, as you say, will keep. Nor can I flatter myself that any one will be the loser if it never be preached at all. Do sermons ever do good, I sometimes ask myself? Yet many of us—I could almost say most of us—do our best. We spare neither time nor trouble nor prayer; but all falls on stony ground, it seems to me. And we are but human—liable to error and mistake, and but few among us have great gift of
- 57. eloquence. It is easy, I know, to pick holes and criticise; but is the fault all on the side of the sermons, I wonder?” “You misunderstood me, Reginald,” said his wife gently. “No, truly; the fault must lie in great part with the hearers. All other efforts to instruct or do good are received with some amount of respect and appreciation. No popular lecturers, for instance, are listened to with such indifference or criticised so captiously as the mass of English clergy. It is the tone of the day, the fashion of the age. Though one rose from the dead—nay, if an angel from heaven came down to preach one Sunday morning,” she went on with sad impressiveness, “he would be found fault with, or sneered at, or criticised, and accused of having nothing to say, or not knowing how to say it; yes, I verily believe it would be so.” Her husband smiled, though his smile was a melancholy one, at her earnestness. “I have it,” he exclaimed suddenly; “I will write to Lyle by to-night’s post. He will come if he can, I am sure, and I know he only preaches occasionally where he is.” The letter was written and despatched. Mr Lyle was a young clergyman doing assistant duty temporarily at a church in the suburbs while waiting for a living promised to him. His answer came by return. He would be glad to do as his friend asked. “But I shall go straight to Saint X’s on Sunday morning,” he wrote. “I shall not probably be able to reach it till the last moment, as I have an early service here. Ask them to count on me for nothing but the sermon. I shall look in after the service and shall hope to find you better.” “He will be here at luncheon, then, I suppose?” said the Rector’s wife—Mildred was her name.
- 58. “Doubtless; at least you will ask him to come. You can wait to see him after the service,” her husband replied. “With you there he will have one attentive hearer, I can safely promise him,” he added, with a smile. “I cannot help listening, even when it is not you, Reginald,” she said naïvely. “It seems to me only natural to do so and to try to gain something at least. We cannot expect perfection in sermons surely, even less than in lesser things. And if the perfection were there, could we, imperfect as we are, recognise it?” Sunday morning rose, bright and glowing over the great city —a real midsummer’s day. “How beautiful it must be in the country to-day!” thought Mildred, as she made her way to church; “it is beautiful even here in town. I wonder why I feel so happy to-day. It is greatly, no doubt, that Reginald is better, and the sunshine is so lovely. When I feel as I do this morning I long to believe that the world is growing better, not worse, that the misery, and the ignorance, and the sins are lessening, however slowly; I feel as if I could give my life to help it on.” There was scarcely any one in the church when she entered and sat down in her accustomed place. Gradually it filled— up the aisles flecked with the brilliant colours of the painted windows, as the sunshine made its way through them, the congregation crowded in, in decorous silence. There were but few poor, few even of the the so-called working classes, for Saint X’s is in a rich and fashionable neighbourhood, yet there was diversity enough and of many kinds among those now pressing in through its doors. There were old, and middle-aged, and young—from the aged lady on her son’s arm, who, as she feebly moved along, said to herself that
- 59. this might perhaps be her last attendance at public worship, to the little round-eyed wondering cherub coming to church for the first time. There was the anxious mother of a family, who came from a vague feeling that it was a right and respectable thing to do, though it was but seldom that she could sufficiently distract her mind from cares and calculations to take in clearly the sense of the words that fell upon her ears. There was the man of learning, who smiled indulgently at the survival of the ancient creeds and customs, while believing them doomed. There were bright and lovely young faces, whose owners, in the heyday of youth and prosperity, found it difficult to put aside for the time the thoughts of present enjoyment for graver matters. There were some in deep mourning, to whom, on the other hand, it seemed impossible that aught in life could ever cheer or interest them again. There were men and women of many different and differing modes of thought, all assembled for the avowed purpose of praying to God and praising Him in company, and of listening to the exhortation or instruction of a man they recognised as empowered to deliver it. And among them all, how many, think you, prayed from the heart and not only with the lips? how many thrilled with solemn rejoicing as the beautiful words of adoration rose with the strains of the organ’s tones? how many ever thought of the “sermon,” save as a most legitimate subject for sharp criticism or indifferent contempt? The service went on with the usual decorum. From her place Mildred could see all that passed. She noticed that the two curates were alone and unaided. “Mr Lyle cannot yet have come,” she thought nervously. “Surely nothing can have detained him?” and a slight misgiving, lest he should not have got away in time, began
- 60. to assail her. But when the moment for commencing the Communion service came, the sight of a third white- surpliced figure removed all her apprehensions, and with a sigh of relief she knelt again, joining her voice to the responses. She observed that the new-comer took no active part in the service; he remained kneeling where she had first perceived him. But it seemed to her that the music and the voices had never sounded so rich and melodious, and once or twice tones caught her ears which she fancied she had not before remarked. “I wonder if it can be Mr Lyle singing,” she thought. “I do not remember if Reginald ever mentioned his having a beautiful voice.” And when the time came for the preacher to ascend the pulpit, she watched for him with increased interest. It needed but the first few syllables which fell from his lips to satisfy her that his was the voice which she had perceived; and with calm yet earnest expectancy she waited to hear what he had to say. At the first glance he looked very young. His face was pale, and he was of a fair complexion. There was nothing in him to strike or attract a careless or superficial observer. But when the soft yet penetrating tones of his voice caught the ear, one felt constrained to bestow a closer attention on the speaker, and this, once given, was not easily withdrawn. For there was a power in his eyes, though their habitual expression was mild, such as it would be vain for me to attempt to describe—a strength and firmness in the lines of the youthful face which marked him as one not used to speak in vain. “Is he young?” thought Mildred more than once. “It seems in some way difficult to believe it, though his features are in
- 61. no way time-worn; and those wonderful eyes are as clear and candid as the eyes of a child that has scarcely yet learned to look out on to this troubled world.” And her perplexity was shared by many among the hearers. They had settled themselves comfortably to listen or not to listen, according to their wont, as the preacher ascended the pulpit steps. A momentary feeling of surprise—in a few cases of disappointment—passed through the congregation on catching sight of the unfamiliar face. “Another new curate, no doubt,” thought a portly and pompous churchwarden. “And what a boy! Well, if the Rector chooses to throw away his money on three when two are quite enough for the work, it is no business of ours. Still, it would be more becoming to consult us, and not to set a beardless youth like that to teach us. I, for one, shall not irritate myself by listening to his platitudes.” And he ensconsed himself more snugly in his corner to carry out his intention. But what was there in that vibrating voice that would be heard?—that so often as Mr Goldmain turned his thoughts in other directions, drew them back again like a flock of rebellious sheep, constraining him to hearken? Then his mood changed: annoyed, he knew not why, he set himself to cavil and object. “Arrant Socialism!” he called the sermon when describing it afterwards. “Shallow, superficial, unpractical nonsense, about drawing all classes together by sympathy and charity. It sounds plausible enough, I daresay; so did many of the theories and doctrines of the first movers in the great French Revolution, I have no doubt. No, no! Let each do his duty in that station of life where God has placed him; that is
- 62. my interpretation of religion. Our great charitable institutions must be kept up, of course, so that the deserving poor may be helped when they really need it; though even among the respectable, in nine cases out of ten, my dear sir, you may believe me, it’s their own fault. But as for this dream of universal brotherhood, ‘of the rich mingling in the daily life of the poor, weeping with them in their sorrows, rejoicing in their joys,’ it is sentimental twaddle. It would revolutionise society, it would break down all the barriers which keep the masses in their places. And to have this nonsense preached to us by a chit of a boy, it makes me lose my temper, I confess. I have not seen our worthy Rector yet, but when I do, I must tell him plainly that if he is not more careful whom he puts in his pulpit when he is absent or ill—hypochondriacal fellow he is, I fancy—I shall look out for seats in some other church than Saint X’s.” Such was Mr Goldmain’s impression of the sermon. For though he closed his eyes in order that those about him might think he was asleep, he did not succeed in achieving even the shortest of dozes. Nay, more, he felt as if mentally stung by nettles for the rest of the day, so irritated, and, though for worlds he would not have confessed it, ill at ease, had the strange preacher’s discourse left him. But the soil of his conscience was choked with thorns; there was room for naught beside. Mr Goldmain was of this world, worldly, and such he remained. He might have spared himself the trouble of thinking of how he appeared to those around him. They were none of them paying any attention to him. In the next seat sat some richly-clad ladies of uncertain age. They had become members of the Saint X’s congregation because they had been told they would find its Rector’s views in no way “extreme.” For these worthy women had an exaggerated
- 63. horror of everything “high,” or, as they expressed it, “verging on papistry.” That God could be worshipped “in spirit and in truth,” in any but their own pet “evangelical” fashion, was a possibility that had not yet suggested itself to their dull brains. And they too, this Sunday morning, felt a shock of disapproval when, looking up at the sound of the vibrating voice, the fair face of the strange preacher met their gaze. “Like a young novice, or whatever it is they call those who are going to be priests; looks as if he fasted and half- starved himself,” whispered one to the other. “The Rector should be more careful. Who knows but what he is a Jesuit in disguise?” replied the third. And at intervals during the sermon little groans or ejaculations of disapproval might have been heard from the seats of the wealthy spinsters. “I did my best not to listen,” said the eldest candidly, as they were walking home, “for I knew in a moment what it was going to be. But no doubt he had a persuasive tone and manner. Poor deluded young man—he will be over to Rome in no time! Did you hear—all that about ‘the Church?’—” “The ‘invisible’ Church, he spoke of also, I think,” suggested the younger sister timidly. “Ah, I daresay, just to hide their real meaning; but I can see through it. There was all that in favour of images, too— symbols he called them. What was it he said, Janet? You have the best memory.” ”‘The childlike expressions of human yearnings after the Divine, which is not for you to condemn or despise,’” quoted Janet.
- 64. “Ah, yes—all very fine. We shall be having Madonnas and rosaries and graven images in our English churches next,” said the eldest sister somewhat confusedly. “He seemed to me a conscientious young man, very much in earnest, I should have said,” observed the younger sister humbly. “Of course, they take that tone; that is the very danger of it,” answered the elder lady. “I really must ask the Rector to be on his guard.” And yet by another group seated just across the aisle the stranger’s sermon had been criticised in a very different fashion. By some among his hearers his views were pronounced to be, not too “high,” or “leading to Rome,” but dangerously “broad.” “I dislike those allusions to ‘evolution’ and ‘development’ in the pulpit. It is not the place for science; our preachers should keep to the Bible, and not give heed to all the talk of the day about matters which have nothing to do with religion,” said an elderly gentleman dogmatically. His companion smiled; they, too, were walking down the street. “Yes, religion or teachers of religion get rather out of their depth when they touch upon science, certainly,” he said. “But if science be true, and religion be true, truths cannot disagree,” said a young girl, who was walking between the two, her bright intelligent face raised to the last speaker, her brother, as he spoke. “You are a very clever and learned man, Gerald, and I am only a very young and ignorant girl, but yet I feel you are wrong, and I never felt this more intensely than when listening to this stranger this morning. Why should we refuse to believe what we cannot
- 65. understand? Is it not the very height of presumption, and even stupidity, to do so? I cannot remember his words, but they seemed to me to say it as I have never heard it said before. And—I hoped you felt it so, too.” But the philosopher only shook his head. The two were some paces in front of the old gentleman by now; they knew that such talk annoyed him, hedged in, in his “orthodoxy.” “I am glad if you were pleased, my dear child,” said the brother; “but I must keep to my old opinion. Reality and dreams cannot be reconciled. We can only know that which we have experience of. Still, I allow that he put it in rather an original way.” “You mean,” said the girl, eagerly, “when he said that our refusing to believe in God and the spiritual universe, because we cannot see and touch them, is like a deaf-mute refusing to believe in music—that we complain of the things of God not being proved and explained to us before we have learned the alphabet of the spiritual language.” “That we complain of not being treated as gods before we have learned to live as men. Yes, that was rather fine,” the other allowed. “But still, my dear child, I cannot see that these discussions are profitable. We have plenty to do and learn about matters as to which we can arrive at certainty. Why not be content to leave those matters as to which we know nothing? I don’t quarrel with the clergy for trying to bring us to a different way of thinking; it is their business, and as long as there are priests, we must submit to their platitudes. But what can a young theologian, determined to see things in but one way, know of the researches of science, the true spirit of philosophy?”
- 66. The girl looked grievously disappointed, and tears filled her beautiful eyes. “Gerald,” she said, “I could not live in the negation of all belief that you advocate; still less,” she went on in a lower voice, “could I die in it. Uncle thought the preacher dangerously ‘liberal;’ you think him narrow and ignorant. For me, I can only say, if I may use the words without irreverence, that my heart burned within me as I listened.” “Little enthusiast!” said her brother, smiling. Mentally he thought to himself that it would really be a pity if Agatha went too far in “that direction,” and his eyes wandering across the street, caught sight of a party of young people, laughing and talking, though in well-bred fashion, as they went along. “She should be more like other girls of her age,” he reflected, as his glance again fell on the thoughtful young face at his side. “You should be pleased and flattered, Agatha,” he said, “that I gave so much attention as I did to this pet preacher of yours.” “I don’t know him, Gerald,” she replied. “I never saw or heard him before.” “Really,” he said, “I had half an idea that you had some reason for so particularly asking me to go to church this morning.” “Oh, no. I expected the Rector would be preaching himself,” she said. “But I am glad you came, Gerald. You do allow that it was a remarkable sermon.” “Ye-es,” he replied, smiling again, and with that Agatha was forced to be contented.
- 67. Across the street the same subject was being discussed. “I feel quite tired,” laughed one of the pretty girls to the man beside her. “Do you know, for once in my life, I really listened to the sermon?” “You don’t mean to say so,” he replied. But something in his tone made her glance up at him archly. “Why do you seem so conscious?” she said. “Were you asleep?” “No, I scarcely think so. I was very sleepy at the beginning, it was so hot. But there was something rather impressive in that fellow’s voice. To confess the truth, I caught myself listening, like you.” “If one could always listen, it would make church-going less wearisome,” said the girl. “As a rule, I never attempt it; they always say the same thing.” “And there was nothing particularly new in what that pale- faced young man had to say this morning, after all,” said her companion. “It was the mere accident of his having an unusually good voice.” “Yes, I suppose so,” replied the young lady, indifferently, “though I’ve really forgotten what it was about—there are too many other things to think about when one is young and—” “Lovely,” interrupted her companion. “Yes—and for my part I don’t see what we’re in the world for, if it isn’t to make ourselves as happy as we can. That’s my religion.” “A very pleasant one, if it has no other merit,” the girl replied, with a laugh.
- 68. At that moment a carriage passed them. It had but one occupant—an elderly lady. Her face, though worn and even prematurely aged, was sweet and calm. Her glance fell for an instant on the upturned laughing face of the girl. “Something in her recalls my Margaret,” thought the lady; “but Margaret was more serious. How is it that they all seem to have been so near me to-day? All my dead children who have left me—I am so glad I went to church. I have not felt so near them all for years. I could almost fancy that young man knew something of my sorrows, his glance rested on me once or twice with such sympathy. How beautiful and how strengthening were his words! Yes—we are not really separated—I am content to wait while God has work for me to do here. And I am glad I am rich when I feel how many I can help. God bless that preacher, whoever he is, for the strength and comfort he has given me to-day.” Mildred in her place sat quietly waiting till the congregation had dispersed. Then she rose and went forward to speak to the verger. “Will you tell the clergyman,” she said, “Mr Lyle is his name —that I hope he will return with me to the rectory to luncheon. I will wait here till he comes out.” The man went with her message. But in a moment or two he reappeared looking somewhat surprised. “He has gone, ma’am,” he said. “I can’t make out how he went off so quickly. No one seems to have seen him.” “He must have hurried off at once. No doubt I shall find him at home,” she said, feeling nevertheless a little disappointed. She had looked forward to the few minutes’ talk with the preacher who had so impressed her; she would have liked to thank him without delay.
- 69. “I shall feel too shy to say it to him before Reginald, I am afraid,” she thought. “I am a little surprised he did not tell me more of this Mr Lyle.” And she set off eagerly to return home. At the church door she almost ran against one of the curates, an honest and hard-working, but dictatorial young man, with whom she did not feel much sympathy. He accompanied her a few steps down the street. “And how did you like the sermon?” he said. Mildred replied by repeating his own question, hoping thus to escape a discussion she felt sure would not be to her mind. “How did you like it, Mr Grenfell?” she asked. He smiled in a superior way, conscious to his fingertips of his unassailable theology. “I daresay he may come to be something of a preacher in time,” he said. “But he was crude—very crude—and I should say he would do well to go through a good course of divinity. He evidently thinks he knows all about it; but if I could have a talk with him I could knock his arguments to shivers, I could—” “Mr Grenfell,” said Mildred, feeling very repelled by his manner, “do you think religion is only theology of the Schools? If you could not feel the love of God, and love to man—the ‘enthusiasm of humanity,’ if you like to call it so— breathing through Mr Lyle’s every word and look and tone, I am sorry for you.” Mr Grenfell grew very red.
- 70. “I am sorry,” he began, “I did not mean—I will think over what you say. Perhaps it is true that we clergy get into that way of thinking—as if religion were a branch of learning more than anything else. Thank you,” and with a shake of the hand he turned away. A step or two further on, Mildred overtook a young man—a cripple, and owing to his infirmity, in poor circumstances, though a gentleman by birth. She was passing with a kindly bow, when he stopped her. “Might I ask the name of the clergyman who preached this morning?” he asked, raising his face, still glowing with pleasure, to hers. “Mr Lyle,” she replied; “at least,” as for the first time a slight misgiving crossed her mind, “I feel almost sure that is his name.” “Thank you,” the cripple said. “I am glad to know it, though it matters little. Whoever he was, I pray God to bless him, I little knew what I was going to church to hear this morning; I felt as if an angel had unawares come to speak to us.” And in the relief of this warm sympathy Mildred held out her hand. “Thank you, Mr Denis, for speaking so,” she said; “you are the first who seem to have felt as I did.” Then she hurried on. She found her husband on the sofa, but looking feverish and uneasy. “How?” he began, but she interrupted him.
- 71. “Is Mr Lyle not here?” she said. “Mr Lyle!” Reginald repeated. “What do you mean? You had scarcely gone when a special messenger brought this from him;” and he held out a short note of excessive regret and apology from the young priest, at finding the utter impossibility of reaching Saint X’s in time for the morning service. “I have been on thorns,” said the Rector, “and I could do nothing. There was no one to send. Did Grenfell preach, or was there no sermon?” Mildred sat down, feeling strangely bewildered. “I cannot explain it,” she said. “Reginald, tell me what is Mr Lyle’s personal appearance? Can he have come after all? even after despatching his message? Is he slight and fair— rather tall and almost boyish-looking, but with most sweet yet keen eyes, and a wonderful voice?” The Rector could hardly help smiling. “Lyle,” he replied, “is slight, but short, and dark—very dark, with a quick lively way of moving, and a rather thin, though clear voice. He has not a grain of music or poetry in his composition.” Nothing could be more unlike the preacher of that morning. Mildred told her husband all she could recollect of the sermon. Its vivid impression remained; but the words had grown hazy, and curiously enough she could not recall the text. But Reginald listened with full sympathy and belief. “I wish I could have heard it,” he said. “Were the days for such blessed visitations not over, I should think.” But there he hesitated.
- 72. Mildred understood, and the words of the cripple, Mr Denis —“an angel unawares”—returned to her memory. The events I have related were never explained, nor of the many who had been present that Sunday morning at Saint X’s did any ever again look upon the fair face of the mysterious stranger. But—till the matter had passed from the minds of all but two or three—the Rector had to listen with patience to much fault-finding with the sermon, and with its preacher. The End.
- 73. | Chapter 1 | | Chapter 2 | | Chapter 3 | | Chapter 4 | | Chapter 5 | | Chapter 6 | | Chapter 7 | | Chapter 8 | | Chapter 9 | | Chapter 10 | | Chapter 11 | | Chapter 12 | | Chapter 13 | | Chapter 14 | | Chapter 15 | | Chapter 16 | | Chapter 17 | | Chapter 18 | | Chapter 19 | | Chapter 20 | | Chapter 21 | | Chapter 22 | | Chapter 23 | | Chapter 24 | | Chapter 25 |
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