SENSITIVITY-ENHANCED AND GRADIENT-ENHANCED HETERO (OMEGA(1)) HALF-FILTERED TOCSY EXPERIMENT FOR MEASURING LONG-RANGE COUPLING-CONSTANTS

An enhanced version of the X(omega(1)) half-filtered TOCSY experiment for measurement of long-range heteronuclear coupling constants is prop osed which yields high-quality spectra with substantially increased se nsitivity and resolution. The modified method features gradient-enhanc ed X filtering sequences, broadband homonuclear decoupling during t(1) , optional (1)J(XH) scaling in the F-1 domain, and gradient coherence selection in combination with the sensitivity-enhanced protocol for th e TOCSY transfer, These modifications extend the applicability of the method-coupling constants can be measured accurately for natural abund ance samples at low concentrations and for compounds yielding complex spectra, Computer-aided analysis of E.COSY-type multiplets is applied for the determination of heteronuclear long-range coupling constants. (C) 1998 Academic Press.