Che 440/540 2D-NMR .

Che 440/540 2D-NMR

http://www.ch.ic.ac.uk/ectoc/echet96/papers/107/index.htm

Relaxation delay

90o pulse

t1 (microseconds)

90o pulse

Prototype Pulse Sequence for a 2D-NMR Experiment

Acquire (t2 seconds)

Stacked plot of 22spectra of acetone

Projection of (a)

Resulting interferogram

Origin of the Second Dimension

Fourier transform of a series of interferograms creates the second dimension.

A Simulated 1H-1H Correlated Spectroscopy (COSY) Spectrum

Actual COSY Spectrum of Isobutanol

OH

A

A BC

A, B

A

B

B,CC

COSY Spectrum of Ipsenol

HO

1

23

4

5 6 7

8

9

Basics of HETCOR and HMQC

• Heteronuclear correlated (HETCOR) and heteronuclear multiple quantum coherence (HMQC) spectroscopy show direct correlations between hydrogens and their directly bonded carbons.

• In HETCOR the signal is detected by observing 13C, and in HMQC by observing 1H. The HMQC experiment is shorter, but the pulse sequence is more complicated.

Both give the same information: one-bond 1H-13C correlations

13C chemicalshifts

1H chemicalshifts

no correlation

A simulated HMQC spectrum

HMQC Spectrum of Ipsenol

diastereotopic CH2’s

COSY Spectrum of Strychnine