Transverse dephasing optimised NMR spectroscopy in solids: natural-abundance 13C correlation spectra

The transverse dephasing optimized (TDOP) approach can be used to obtain heteronuclear decoupling sequences that increase significantly coherence lifetimes in solid-state NMR spectroscopy, leading to a dramatic improvement in the sensitivity of correlation experiments. Herein we demonstrate experimentally on several model organic compounds that, by applying this procedure, solid-state 13C-refocused INADEQUATE experiments are feasible at natural abundance on medium-sized molecules. Examples are provided for powdered crystalline cholesteryl acetate as well as for a sample of brucine, a less ordered compound. Effects of molecular dynamics on the sensitivity of the experiment are also discussed for a sample of tyrosine ethyl ester.