Progress in Multiple-Quantum Magic-Angle Spinning NMR Spectroscopy

Abstract

Recent advances in nuclear magnetic resonance spectroscopy of quadrupolar (I>1/2) nuclei with half-integer spins in solids have been reviewed. The advent of multiple-quantum (MQ) magic-angle spinning (MAS) spectroscopy gave new momentum to the study of quadrupolar nuclei in materials of academic and industrial interest such as minerals, ceramics and glasses, microporous and mesoporous solids and biological materials. It is now possible to record high-resolution solid-state NMR spectra of a range of important nuclei, namely ¹¹B, ¹⁷O, ²³Na, ²⁷Al, ⁷¹Ga, ⁹¹Nb. Since its introduction in 1995 MQMAS NMR has evolved considerably and, at present, a range of very useful related techniques are available and have been reviewed, in particular satellite transition (ST) MAS, Inverse-STMAS NMR, fast amplitude modulation, and techniques based on the dipolar interactions between quadrupolar and spin-1/2 nuclei, such as cross-polarization MQMAS and MQ heteronuclear correlation spectroscopy (HETCOR) and the recently introduced J-coupling based experiments (such as J-HMQC).