Improved Performance Accordion Heteronuclear Multiple-Bond Correlation Spectroscopy-IMPEACH-MBC

摘要

A modification of the recently reported ACCORD-HMBC longrange heteronuclear shift correlation experiment is described. The new experiment, IMPEACH-MAC (improved performance accordion heteronuclear multiple-bond correlation), introduces a new pulse sequence element, a constant time variable delay. The incorporation of the constant time variable delay into the IMPEACH-MBC sequence suppresses ~1H-~1H coupling modulation inherent to the utilization of the accordion principle to sample a broad range of potential long-range heteronuclear couplings. ~1H-~1H coupling modulation, which introduces an F_1 modulation or a "skew" of responses in the second frequency domain of the ACCORD-HMBC experiment, is suppressed in the IMPEACH-MBC experiment. Results of identically optimized IMPEACH-MBC and ACCORD-HMBC experiments performed on a sample of strychnine are compared.