Heteronuclear 2D J-spectroscopy

Heteronuclear 2D J spectroscopy was first demonstrated on the proton-coupled carbon-13 quartet of iodomethane 36 spectra of this type appeared in a bewildering variety of guises in the subsequent months, as heteronuclear J spectroscopy proved an ideal vehicle for the development of experimental methods in two-dimensional NMR.37 38 The principal motivation for early work on J spectroscopy was the suppression of static field inhomogeneity effects in fj, in order to allow very high resolution studies of proton-coupling fine structure in carbon-13 spectra. 

Figure 9. Pulse sequence used in acquiring the spectrum of Figure 8 this "gated decoupler" method for heteronuclear 2D J spectroscopy results in the multiplet splittings in fj appearing to be halved.

The third class are /-resolved experiments. These produce spectra with the peaks at the frequencies along /2 corresponding to the resonances observed in the ID spectrum of the detected nucleus. In homonu-clear 2D /-spectroscopy, the peaks are dispersed into the fi dimension based on homonuclear /-coupling. In heteronuclear 2D J-spectroscopy, the peaks are dispersed into the dimension based on heteronuclear /-coupling (e.g. detection of in fi and at the shift of each a multiplet, resulting from all of the resolved /(-p couplings, is observed in / ). 

D.L. Foxall, Broadband Decoupled Heteronuclear Correlation and Semiselective Heteronuclear 2D J Spectroscopy, Varian Application Note, 1984. 

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