Cosy,nosy

COSY NOSY NMR

1. Prepared By : Mahendra G S M-Pharm, Pharmaceutical Chemistry JSSCP, MYSURU 2D NMR: Cosy,Nosy, Hector

2. Need for 2D NMR!!!

3. Need of the Hour: 2D Nuclear Magnetic Resonance(NMR) The first two-dimensional experiment was proposed by Jean Jenner . 2D NMR is a set of nuclear magnetic resonance spectroscopy (NMR) methods which give data plotted in a space defined by two frequency axes rather than one. 2D NMR spectra provide more information about a molecule than one-dimensional NMR spectra.

4. 2D NMR is Nuclear magnetic resonance spectroscopy in which we provide a 90 degree pulse to our sample which is placed in uniform magnetic field then we wait for (0ms-5ms ) depending upon the experiment type then again we provide again 90 degree pulse and this time we measure signal as FID. As a result we get Two FID signals which are plotted with respect to time domain. To get a meaningful data , we apply Fourier transform program on FIDs to get frequency in terms of ppm. Principle of 2D NMR

5. Stages of 2D NMR: Preparation : 90 degree pulse excite nuclei in sample. Evolution (t1) : let them nuclei precision freely. Mixing : again 90 degree radio Frequency pulses are applied and create transverse magnetization Detection (t2): observable transverse magnetization is recorded. It is usually labeled with t2

6. Cosy- Correlation Spectroscopy Noesy - Nuclear Over Hauser effect Spectroscopy Hetcor -Heteronuclear Correlation Many Others like: Ecosy Roesy Tcosy Types of 2D NMR

7. COSY- Correlation Spectroscopy COSY The two axes now both correspond to the 1 H NMR spectrum . 1 H- 1 H COSY provides connectivity information by allowing one to identify spin-coupled protons. x,y -coordinates of cross peaks are spin-coupled protons .

8. The two-dimensional spectrum that results from the COSY experiment shows the frequencies for a single isotope , most commonly hydrogen ( 1 H) along both axes. COSY spectra show two types of peaks: A. Diagonal peaks  B. cross peaks  

9. H-H COSY Spectrum

10. Example- Nitropropane C NO 2 CH 3 H C H 3 doublet septet

11. C NO 2 CH 3 H - CH 3 - CH 3 - CH - CH Points on diagonal: H’s correlated with themselves! Not important.

12. COSY Spectrum Methyl Ethyl Ketone b a c c a b

13. 1 H and 13 C spectra plotted separately on two frequency axes Coordinates of cross peak connect signal of carbon to protons that are bonded to it. Hetcor -Heteronuclear Spectroscopy

14. 1 H- 13 C HETCOR 1 H-NMR 13 C-NMR

15. COSY: 1 H- 1 H correlations via spin coupling interactions, nuclei must be closely connected by bonds . NOESY is a type of 2D NMR that is also a 1 H- 1 H correlation. It correlates nuclei that are physically near each other in space , but not necessarily coupled to one another. It takes advantage of the Nuclear Overhauser Effect, recall from our discussion of 13 C NMR. Nuclear Over Hauser effect Spectroscopy( Noesy )

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