Solid‐State NMR Spectroscopy

Solution proton and carbon nuclear magnetic resonance (1H and 13C NMR) are widely used for the study of drugs, being employed for structure elucidation or identification. One advantage of solid-state NMR is that it offers the potential for analysis of mixed crystals or mixtures because signals from crystal-lographically distinct but chemically identical sites are often resolvable. One advantage of solid-state NMR is that it offers the potential for analysis of mixed crystals or mixtures because signals from crystallographically distinct but chemically identical sites are often resolvable. Solid-state NMR spectroscopy was developed by Schaefer and Stejskal who combined high-powered proton decoupling with cross-polarization (CP) and magic-angle spinning (MAS), techniques that provided an enormous increase in the resolution and sensitivity of solid-state spectra. A complete understanding of the CP experiment requires an understanding of the concept of spin temperature and spin diffusion in solids.