Directly and indirectly detected through-bond heteronuclear correlation solid-state NMR spectroscopy under fast MAS

摘要

Two-dimensional through-bond H-1{C-13} Solid-state NMR experiments utilizing fast magic angle spinning (MAS) and homonuclear multipulse H-1 decoupling are presented. Remarkable efficiency of polarization transfer can be achieved at MAS rates exceeding 40 kHz, which is instrumental in these measurements. Schemes utilizing direct and indirect detection of heteronuclei are compared in terms of resolution and sensitivity. A simple procedure for optimization of H-1 homonuclear decoupling sequences under these conditions is proposed. The capabilities of these techniques were confirmed on two naturally abundant solids, tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (f-MLF-OH) and brown coal.