Che 440/540 2D-NMR

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

Prototype Pulse Sequence for a 2D-NMR Experiment Relaxation delay 90 o pulse 90 

t

1 (microseconds) o pulse Acquire (

t

2 seconds)

Origin of the Second Dimension Stacked plot of 22 spectra of acetone Resulting interferogram Projection of (a)

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

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

Actual COSY Spectrum of Isobutanol A A B C OH A B A, B C B,C

9 HO 5 4 6 3 2 7 8 1 COSY Spectrum of Ipsenol

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

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

A simulated HMQC spectrum 1 H chemical shifts 13 C chemical shifts no correlation

HMQC Spectrum of Ipsenol diastereotopic CH 2 ’s

COSY Spectrum of Strychnine