Measuring J_HH values with a selective constant-time 2D NMR protocol

Proton-proton scalar couplings play important roles in molecule structure elucidation. However, measurements of J_HH values in complex coupled spin systems remain challenging. In this study, we develop a selective constant-time (SECT) 2D NMR protocol with which scalar coupling networks involving chosen protons can be revealed, and corresponding J_HH values can be measured through doublets along the F1 dimension. All J_HH values within a network of n fully coupled protons can be separately determined with (n − 1) SECT experiments. Additionally, the proposed pulse sequence possesses satisfactory sensitivity and handy implementation. Therefore, it will interest scientists who intend to address structural analyzes of molecules with overcrowded spectra, and may greatly facilitate the applications of scalar-coupling constants in molecule structure studies.