Homonuclear decoupling in the 13C indirect dimension of HSQC experiments for 13C‐enriched compounds

• Published in: Magnetic resonance in chemistry 2018-10, Vol.56 (10), p.1021-1028
• Main Authors: Brucka, Marta, Sheberstov, Kirill F., Jeannerat, Damien
• Format: Article
• Language: English
• Subjects: 13C; 13C‐enriched compounds; Broadband; broadband homonuclear decoupling; Carbon; Carbon 13; Cholesterol; Decoupling; HSQC; modulated selective pulses; NMR; PSYCHE; saltire chirps; Spectral sensitivity; Zangger–Sterk
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.4697

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 13C 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 13C‐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. Elimination of the homonuclear 13C–13C coupling interactions was successfully achieved in the indirect dimension of the HSQC experiment of 13C‐enriched cholesterol. The implementation of the Zangger–Sterk method with non‐equidistantly modulated selective pulse and the pure shift yielded by chirp excitation (PSYCHE) method, respectively, produced decoupled HSQC spectra with improved quality compared to earlier results.