Constant time inverse-detection gradient accordion rescaled heteronuclear multiple bond correlation spectroscopy: CIGAR-HMBC

A further refinement of the recently reported IMPEACH MBC long-range hetero nuclear shift correlation experiment is described. The new experiment, CIGA R-HMBC (constant time inverse-detected gradient accordion rescaled long-ran ge heteronuclear multiple bond correlation), modifies the constant time var iable delay of the IMPEACI.-MBC experiment to allow user-determined scaling of Fl modulation. The refinement offered in the CIGAR-HMBC experiment allo ws the investigator to reintroduce whatever degree of Fl modulation is desi red to authenticate weak long-range responses. Results obtained with the CI GAR-HMBC experiment using a range of values for J(scale) are compared with results obtained with identically optimized ACCORD-HMBC and IMPEACH-MBC exp eriments. Copyright (C) 2000 John Wiley & Sons, Ltd.