Analysis of isotropic chemical shift data from high-resolution solid-state NMR studies of hydrogen-bonded organic compounds

Abstract

The importance of nuclear magnetic resonance (NMR) spectroscopy to the development of modern-day organic chemistry cannot be overestimated. Nevertheless, until very recently routine NMR analyses had to be performed on solutions. In this paper, the application of high-resolution solid-state NMR methods, in particular 13C CP/MAS NMR, to the study of structural properties and hydrogen-bonded solids is reviewed. As a complementary tool to X-ray crystallography, NMR offers the ability to study non-crystalline and heterogeneous materials as well as single crystals and polycrystalline samples, to collect data rapidly (minutes to hours), to use chemically non-destructive methods, and to probe specific nuclei in the sample independently. The two types of spectral information that are usually analyzed are chemical shifts, which are related to the local chemical and electronic environment of an atom, and relaxation times, which are related to dynamic properties of the sample. Examples presented here of the use of solid-state NMR to study molecular structures include the study of keto—enol tautomers in the solid state, packing patterns of organic molecules with inter- and intramolecular hydrogen bonds, phase changes in hydrogen-bonded solids, and proton transfer in the solid state.