Use of reverse cross-polarization for editing solid-state proton NMR spectra

We present here the use of the cross-polarization - reverse cross-polarization (CP-RCP) method for editing proton spectra by identifying protons attached exclusively to a nucleus such as carbon or nitrogen. Experiments have been done at moderate spinning speeds utilizing the Combined Rotation and Multi-Pulse Scheme (CRAMPS) technique which provided resolution of the spectral lines that is sufficient for several small molecular systems. This approach, in addition to being an editing tool, helps to increase resolution further and also leads to identifying protons such as the OH and the SH protons. Here we present results of the application of the CP-RCP scheme to systems at natural abundance of the nuclei 13C and 15N. The utility of the method has been illustrated for the case several amino acids, a tri-peptide and a synthesized cocrystal.