1H13C two-dimensional chemical shift correlation spectroscopy using DEPT

The DEPT sequence (I) is readily extended to two-dimensional (2D) heteronuclear NMR applications, a number of which we describe briefly. In more detail, we show that it can be extended to ‘H-13C chemical shift correlation spectroscopy, by including appropriate incremented delay periods, but without additional pulses. The method has several valuable advantages over the normal form (2) of ‘H-13C chemical shift correlation spectroscopy. First, provided phase-sensitive 2D software is available, separate CH3, CH2, and CH 2D subspectra, i.e., 2D spectrum editing, may be achieved. Second, phase errors are fully refocused using the DEPT sequence and thus also the 2D DEPT sequence. This enables phase correction in both dimensions, thus improving lineshapes by eliminating the need to do a magnitude calculation as is normally done. Third, the normal form of heteronuclear chemical shift correlation spectroscopy may also be improved by the addition of refocusing pulses so that phase errors are refocused. The resulting 7 or 8 pulse sequences (sequences [C] and [B] of Ref. (3)) may be considered to be 2D extensions of the INEPT (4) sequence. Thus it is also possible to achieve 2D spectrum editing with these methods in the same way as one-dimensional editing using INEPT (3). But the 2D DEPT sequence described here contains fewer pulses and is also more accurate for spectrum editing, just as DEPT is more accurate than INEPT for one-dimensional editing (1).