Homonuclear decoupling in the C indirect dimension of HSQC experiments for C-enriched compounds.

The two most compelling methods for broadband homonuclear decoupling currently available, Zangger-Sterk (ZS) and pure shift yielded by chirp excitation (PSYCHE), were successfully adapted and tested on the C isotope. When applied during the indirect carbon evolution in the HSQC experiment, they both entirely eliminated the extended carbon-carbon multiplet structures observed in this dimension of a non-decoupled HSQC spectrum of C-enriched cholesterol. The optimized selective pulse modulated using novel non-equidistant scheme for multisite refocusing (ZS) and the small flip angle saltire chirps (PSYCHE) both proved to be robust and efficient in providing decoupled spectra with a sensitivity of about 25% that of the non-decoupled HSQC spectra with improved quality compared to earlier results.