1. NMR Nuclear Magnetic Resonance Dr. A.G. Nikalje
Pharmaceutical Chemistry Department

3. 1H, 13C, 15N, 19F, 31P

4. One Level is more populated than the other
Therefore a Resulting Net Magnetization will be Macroscopically Observable

5. CW Continous Wave

6. The Exact Resonance Frequency Varies with the Chemical and Electronical Environment of the Nucleus – This is Called the Chemical Shift d (measured in ppm)

7. The Chemical Shift is Measured Relative to a Reference or ‘Standard’ ppm ‘parts per million’ d=(w-wref)/wref * 106
The most common standard for 1H and 13C NMR is
TMS Tetramethylsilan
CH3
CH3 – Si - CH3

9. NMR is ‘quantitative’
The intensity is measured as the integral below the resonance signal. The intensities are proportional to the number of protons, that contribute to the signal.

11. Each Particular Arrangement of Nuclei has a Characteristic
Coupling Pattern n Neighbors – (n+1) Lines
A – B
B – A – B
C – B – A

12. CH2 CH3 example No spin-spin coupling is observed if:
protons are separated by four or more single bonds, i.e.,  
H-C-C-C-H
protons are equivalent, i.e.,within a CH3 or CH2 group

13. Pick the molecule that gives rise to the following 1H NMR spectrum!

14. Assign the Signals to the Correct Hydrogens

16. (almost) pure a D Glucose
~50% - 50% a/b D Glucose

17. FT NMR
‘Pulse Echo’ NMR
‘Broadband Excitation’
Record ‘Transient Response’
FID Free Induction Decay
Extract Frequencies by
Fourier Transform to get NMR Spectrum

21. More Complex Experiments
Measurement of Relaxation Times (‘Lifetimes’)
Inversion Recovery

25. ?

27. ?

28. 13C NMR Spectroscopy
Sensitivity low: only 1.1% natural abundance
Complicated 1H coupling pattern,
no couplings between 13Cs (due to low abundance)
S/N can be improved by 1H ‘broadband decoupling’ and FT averaging

29. 3JHH coupling constants contain
Geometrical Information on Torsion Angles
‘Karplus Relation’

31. COSY Correlated SpectroscopY
Two Dimensional NMR Spectroscopy
A Signal as a function of two times becomes after 2D FT
Spectrum as a function of two frequencies
Usually presented as ‘contour plot’
COSY Correlated SpectroscopY

33. Cyclosporin A

34. Hb
CH3g/d etc HN Ha

35. ‘complex’ spectra can be resolved using 2dimensional NMR methods