Structure elucidation by computer use
- 2. ROLE OF COMPUTER IN DETERMINATION OF MOLECULAR STRUCTURES • SUBMITTED TO: • MAM AMINA UMER • SUBMITTED BY: • 2018-CH-9 • 2018-CH-35 • 2018-CH-57
- 3. HAMZA SOHAIL • IR Spectroscopy • X-ray Crystallography • Electron Diffraction • Nuclear Magnetic Resonance Spectroscopy
- 4. Infra Red Spectroscopy For determination of molecular structures Most powerful Technique Atoms start vibrating due to IR rays Vibrating Phenomen on At which those vibrations happened Frequency Determina tion
- 5. X-RAY CRYSTALLOGRAPHY X rays beam directed at crystal Core electrons diffract x rays Mobile detector that measures position and relative intensities Electron density map 3D image projected on computer
- 6. ELECTRON DIFFRACTION Much similar to X-ray crystallography Beam of electron that scatter off molecular electrons Much smaller and low melting Must maintain its structure Accuracy of atom location is lower
- 7. 50 years ago •Most efficient technique •Complete analysis Non destructive technique •Latest Instruments •Large amount of sample required Very accurate technique •Sample weighing less than a milligram •Physical Principles must understand Nuclear Magnetic Resonance Spectroscopy
- 8. NMR Isotopes have characteristics spin Integral spin 1, 2, 3 etc. Structure determined by computer By using spin Few have no spin C-12, O-16 etc. Fractional spin 0.5, 1.5 etc.
- 9. Spinning charge produces magnetic field Two states of spin exists +1/2 & -1/2 Energy difference is very small ∆𝐸 depends upon external 𝐁 Characteristics
- 10. Figure shows that spin states have same E when B is zero Spin states diverge when field increases Two states of spin
- 11. Strong magnetic field is necessary Earth’s magnetic field does not remain constant Latest instruments use magnets of magnetic field 1- 20 T At ground level=0.0001 T SI unit of B is Tesla
- 12. • Even at high fields, energy difference is less than 0.1 calorie per mole. • For nmr purposes small energy difference depend upon: • 1). Strength of magnetic field • 2). Specific nucleus • Usually given in terms of frequency in units of Mega Hertz (MHz) • Ranging from 20-900 MHz.
- 14. COMPUTER GENERATION OF MOLECULAR STRUCTURE BY THE SMOG PROGRAM MUHAMMAD AHMED
- 15. ROLE OF COMPUTER IN DETERMINING MOLECULAR STRUCTURES • Abstract : 1. Theoretical Graph Algorithm 2. Effectively use for substructures 3. Consideration of various Valence states 4. Forbidden structures 5. Output graphs visualized as 2D
- 16. INTRODUCTION TO SMOG PROGRAM • Importance in mathematical chemistry • Important in developing organic structures • SMOG software designer • Main objective • Techniques like Spectroscopy and QASAR studies etc.
- 17. ELEMENTS OF METHADOLOGY Molecular Graphs Various Valence states
- 18. VARIOUS VALENCE STATES Valence state of elements Generation process repeated Considering example of C2H2N2O
- 19. FlowsheetDiagram
- 20. CONCLUSION conclusion SMOG programs runs on IBM PC compatible computer with an EGA or VGA card. SMOG program is written in CC++ Required 2-3 Mb for storing structure The program occupies 1 Mb of disk space.
- 22. HISTORY
- 23. 19 𝑡ℎ century • Computer-assisted Method CASE • Computer-aided Structure Elucidation • information extracted from different forms of spectra Forty years ago • CASE was applied to "small molecules" • The First Reports Concerned To Case Systems Were Published History
- 25. General principles of the CASE systems A molecule as a "machine" for coding structural information we excite the system with electromagnetic radiation . we obtain IR, UV-VIS, NMR, Raman and mass-spectra The molecule under analysis acts like a specific coding machine The goal of a analyst is to decode these codes and extract the max information of a structure
- 26. Sample Footer Text 1/17/2019 26 Some examples
- 28. At this time, well over a quarter million new compounds are synthesized and about 27 million compounds have been identified The StrucEluc system (structure elucidation) provides capabilities to form user databases It can be successfully used for the creation of a user database even if only one compound of a similar structure is known User data base application
- 29. SYSTEM EFFICIENCY AND FUTURE WORK StrucEl uc system System is based on highly sophisticated, flexible for structure generation Developed for the calculations of properties of organic molecules from their structures Widely used at many pharmaceutical companies and universities worldwide The total time for solving problems < one minute
- 30. MOST COMMON SOFTWARE'S OF CASE • Mnova • CMC-se by Bruker
- 34. It’s use in different areas
- 36. •Fully automated structure elucidation •Will receive increasing acceptance in the next decade •StrucEluc system is still being intensively developed •Developed over a period of forty years This development path has forced the developers to solve many problems for the development of a software capable reducing the time and effort In order to expand the general application, improved workflows and usability of the system and increased reliability of results The efficiency of expert systems is enhanced the solution of increasingly complex structural problems will be achievable. Ultimately be integrated directly to analytical instruments for the purpose of organic analysis Conclusion