Effects of a solid proton transfer on the 13C, 14N residual dipolar coupling in CPMAS NMR. Implications for the shape of the potential energy function

A rapid spin–lattice 14N relaxation caused by an N–H proton transfer reaction in the solid state is likely to affect the 13C, 14N residual dipolar coupling generally observed in 13C CPMAS spectroscopy. A simple analysis is presented for studying the conditions under which the carbon resonances will be self-decoupled from the influence of 14N nuclei. The implications of the results as to the nature of the proton potential energy profile are also discussed.