Two-dimensional NMR (2D-NMR) techniques such as COSY and HETCOR provide additional structural information about molecules beyond what can be learned from one-dimensional NMR. COSY identifies protons that are spin-coupled to each other, while HETCOR connects carbon signals to the protons bonded to those carbons. These 2D NMR techniques simplify analysis of complex molecules like proteins by separating overlapping signals.

1. Two-Dimensional NMR (2D-NMR)
Prepared By
MAHENDRA G S
Pharmaceutical Chemistry
JSSCP,Mysuru.

2. Two-Dimensional NMR (2D-NMR)
2
•Basis: interaction of nuclear spins (1H with 1H, 1H with 13C, etc.) plotted in two dimensions
•Applications:
Simplifies analysis of more complex or ambiguous cases such as proteins
Obtain structural information not accessible by one-dimensional NMR methods
•Techniques include:
Correlation Spectroscopy (COSY)
Heteronuclear Correlation Spectroscopy (HETCOR)
Heteronuclear Multiple-Quantum Coherence (HMQC)
Nuclear Overhauser Effect Spectroscopy (NOESY)
Incredible Natural Abundance Double Quantum Transfer Experiment (INADEQUATE)
Many others

3. 2D-NMR
3
COSY: Correlation of 1H-1H coupling
O
O
H
CH2OH
O
H
CH2OH
HO
H
OH
H
H
HO
HO
HO
H
H
CH2
H
OH
1
2
3
4
5
6
7
8
9
10
11
12
•Dots = correlations
•Ignore dots on diagonal
Sucrose 1H-NMR
Sucrose1H-NMR
Examples
•H6 and H5 are coupled
•Identify H8 by its coupling with H9
H8

4. 1D NMR = 1 frequency axis
2D NMR = 2 frequency axes
COSY = Correlated Spectroscopy
1H-1H COSY provides connectivity information
by allowing one to identify spin-coupled protons.
x,y-coordinates of cross peaks are spin-coupled
protons
2D NMR:
COSY AND HETCOR

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

6. Interpreting a 1H-1H COSY Spectrum
1. Draw a diagonal line from the lower left to
upper right corner. Each contour represent
carbons bond to H in the compound.
2. The contours not on the diagonal are called
cross peaks. The connectivity information is
found here.

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

8. COSY Spectrum
Methyl Ethyl Ketone
connectivity
b
a c
c
a
b

9. 1H-1H COSY ii i iii iv v
v
iv
iii
i
ii

10. 1H-1H COSY
No connectivity
i
i

11. 1H-1H COSY
a)
b)
ii
iii

12. 1H-1H COSY
a)
b)
c)
iii
iii
iv

13. 1H-1H COSY
a)
b)
c) d)
e)
iv
iv
v

14. 1H-1H COSY
a)
b)
c) d)
e)
f)

15. 1H and 13C spectra plotted separately on two
frequency axes
Coordinates of cross peak connect signal of carbon
to protons that are bonded to it.
HETCOR

16. 1H-13C HETCOR
1H-NMR
13C-NMR

17. 1H-13C HETCORO
13C
1H
v
iv
iii
i
ii
1H-NMR
13C-NMR
CH3COCH2CH2CH2CH3