Multiple - quantum magic - angle spinning NMR: a new technique for probing quadrupolar nuclei in solids

Abstract

Recentemente descrevemos um nova técnica capaz de obter espectros de RMN de alta resolução de núcleos quadrupolares com spins múltiplos de 1/2 no estado sólido, baseada no uso combinado de rotação no ângulo mágico (MAS) e espectroscopia múltipla quântica 1 (MQ). Esta revisão descreve aspectos da teoria básica que suporta o experimento de RMN MQMAS de alta resolução e também enfatiza aspectos práticos envolvidos na otimização de sua relação sinal/ruído.Descrevemos também características da forma das linhas espectrais da MQMAS exemplificando com algumas aplicações para vários núcleos quadrupolares.É discutido também a ocorrência de padrões não usuais de bandas laterais ao longo do domínio múltiplo quântico; referências adicionais, que surgiram na literatura recentemente sobre o progresso desta técnica, são também apresentadas. We have recently described a new technique capable of recording high resolution NMR spectra of half-integer quadrupolar nuclei in solid samples, based on the combined use of magic-anglespinning (MAS) and multiple-quantum (MQ) spectroscopy 1. This review summarizes the basic theoretical aspects underlying this high resolution MQMAS NMR experiment, emphasizing as well practical aspects involved in the optimization of its signal-to-noise. We also describe the features of MQMAS spectral lineshapes, and exemplify these with a number of applications on various quadrupolar nuclei. Also discussed is the occurrence of unusual spinning sideband patterns along the multiple-quantum domain; additional references to ongoing progress in the area that has appeared in the recent literature are also presented.

Nucleation and growth of zeolites and inorganic mesoporous solids: Molecular insights from magnetic resonance spectroscopy

“…In particular, multiple-quantum MAS (MQ-MAS) [54][55][56][57] is now widely used to enhance the resolution of solid-state NMR spectra of half-integer quadrupolar nuclei by averaging anisotropic second-order quadrupolar interactions. MQ-MAS is an echo technique that correlates multiplequantum (e.g., often triple-quantum) and single-quantum coherences under MAS conditions.…”

The Route to the Structure Determination of Amorphous Solids: A Case Study of the Ceramic Si3B3N7

“…This problem can be overcome by employing techniques capable of averaging the fourth Legendre polynomial. Among the various strategies developed-dynamic angle spinning (DAS), [49,50] double rotation (DOR), [51,52] and multiple quantum MAS (MQMAS) [53][54][55][56][57] -the latter has attracted much attention because of the versatility and ease of use of the approach.…”

11B-MQMAS and 29Si–{11B} Double-Resonance NMR Studies on the Structure of Binary B2O3–SiO2 Glasses

“…In recent years, however, considerable progress has been achieved in the resolution of quadrupolar broadened MAS NMR spectra. Predominantly, MQMAS spectroscopy, introduced in 1995 by Frydman and coworkers [14][15][16], attracted much attention due to the versatility and ease of use of this approach. In MQMAS spectroscopy, the evolution of a multiple quantum coherence is correlated with the evolution of a single quantum coherence under the conditions of fast MAS, resulting in a separation of the isotropic chemical shifts and the quadrupolar broadening in a 2D experiment.…”