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無機物理方法（核磁共振部分）

無機物理方法（核磁共振部分）. The Physical Methods in Inorganic Chemistry (Fall Term, 2004) (Fall Term, 2005) Department of Chemistry National Sun Yat-sen University. Chemical Shift and J-Coupling. Chemical Shift. The surrounding electrons cause a shielding magnetic field at the nucleus.

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無機物理方法（核磁共振部分）

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  1. 無機物理方法（核磁共振部分） The Physical Methods in Inorganic Chemistry(Fall Term, 2004) (Fall Term, 2005)Department of ChemistryNational Sun Yat-sen University

  2. Chemical Shift and J-Coupling

  3. Chemical Shift The surrounding electrons cause a shielding magnetic field at the nucleus

  4. Different environments cause different shieldings (Representing different local chemical environments, Proctor and Yu, 1951)

  5. Shielding Anisotropy (CSA) Electron clouds are seldom spherically symmetrical. They are anisotropic in almost all molecules. B0 B0 Chemical shift anisotropy (CSA) tensor In liquids, CSA is averaged out by rapid molecular tumbling; in solids, CSA is kept.

  6. Oriented Molecules B0

  7. Oriented Single Crystals B0

  8. Powder (Polycrystalline Solid) B0

  9. Chemical Shift Tensor

  10. Anti-shielding Is Possible

  11. Some proton chemical shifts Most shielded Reference shift Least shielded

  12. CHARACTERISTIC PROTON CHEMICAL SHIFTS

  13. Carbon-13 Chemical Shifts

  14. Phosphorous-31 Chemical Shifts

  15. Phosphorous (III) Chemical Shift Table (from Bruker Almanac 1991)

  16. Phosphorous (V) Chemical Shift Table (from Bruker Almanac 1991)

  17. Fluorine-19 Chemical Shifts

  18. Nitrogen-14 Chemical Shifts

  19. B-11 Chemical Shift

  20. Factors Affecting Chemical Shift • Temperature • Solvents (pH, concentration) • Pressure

  21. Major Contributions To CS

  22. Applications of Chemical Shift

  23. Applications of Chemical Shift http://www.bmrb.wisc.edu/data_access/outlier_selection_grid.html

  24. Applications of Chemical Shift

  25. Applications of Chemical Shift Relaxation, dynamics Solid state NMR CS Imaging ……

  26. Story Goes On

  27. N N S S Indirect Dipolar Interaction(J-Coupling) Interaction between spins mediated by electrons around them. J-coupling is usually much smaller than direct dipolar coupling.

  28. NMR/I J-Coupling

  29. Homonuclear system

  30. X X A X A Heteronuclear SystemAX System

  31. General Cases of Two-Site Homonuclear Systems 000…00 00000…000 100…00 10000…000 010…00 01000…000 1=“up” 0=“down” 001…00 00100…000 Spin A: … … 110…00 11000…000 011…00 01100…000 0011..00 00110…000 Spin B: … … 111…01 11111…101 111…10 11111…110 111…11 11111…111 Spin A Spin B

  32. Exercise: Who are They?

  33. ABC System

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