Enhanced sensitivity in high-resolution H-1 solid-state NMR spectroscopy with DUMBO dipolar decoupling under ultra-fast MAS

The solid-state NMR H-1 homonuclear decoupling sequences in the DUMBO family are shown to be effective at ultra-fast MAS rates of up to 65 kHz. The sequences are applied to model compounds glycine and [2-C-13]-L-alanine as well as the dipeptide beta-L-Asp-L-Ala in windowed and continuous phase-modulated versions. They are shown to achieve especially impressive resolution when implemented in a 2D constant-time experiment. At 65 kHz MAS, H-1 resolution using homonuclear decoupling is similar to that obtained at lower MAS rates, but peak intensity, and therefore spectral sensitivity, is improved by a factor of 5 over homonuclear-decoupled spectra at 10 kHz MAS. (C) 2008 Elsevier B. V. All rights reserved.