Resolution enhancement and proton proximity probed by 3D TQ/DQ/SQ proton NMR spectroscopy under ultrafast magic-angle-spinning beyond 70 kHz

摘要: Abstract Proton nuclear magnetic resonance (NMR) in solid state has gained significant attention recent years due to the remarkable resolution and sensitivity enhancement afforded by ultrafast magic-angle-spinning (MAS). In spite of substantial suppression 1H-1H dipolar couplings, proton spectral is still poor compared that 13C or 15N NMR, rendering it challenging for structural conformational analysis complex chemicals biological solids. Herein, utilizing benefits double-quantum (DQ) triple-quantum (TQ) coherences, we propose a 3D single-channel pulse sequence correlates triple-quantum/double-quantum/single-quantum (TQ/DQ/SQ) chemical shifts. addition two-spin proximity information, this TQ/DQ/SQ enables more reliable extraction three-spin information regular 2D TQ/SQ correlation experiment, which could aid revealing network Furthermore, TQ/DQ slice taken at specific SQ shift only reveals local correlations corresponding shift, thus accurate assignments peaks along TQ DQ dimensions simplifies interpretation spectra especially dense networks. The high performance well demonstrated on small compounds, L-alanine tripeptide, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (MLF). We expect new methodology can inspire development multidimensional solid-state NMR sequences using merits coherences enable high-throughput investigations solids abundant protons.