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Perspectives of fast magic‐angle spinning 87 Rb NMR of organic solids at high magnetic fields
Author(s) -
Wu Gang,
Terskikh Victor,
Wong Alan
Publication year - 2021
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.5097
Subject(s) - chemistry , carbon 13 nmr satellite , nmr spectra database , magic angle spinning , quadrupole , solid state nuclear magnetic resonance , ionophore , magic angle , analytical chemistry (journal) , nuclear magnetic resonance spectroscopy , alkali metal , chemical shift , spectral line , nuclear magnetic resonance crystallography , fluorine 19 nmr , nuclear magnetic resonance , stereochemistry , atomic physics , organic chemistry , physics , astronomy , calcium
We report solid‐state 87 Rb NMR spectra from two Rb‐ionophore complexes obtained with fast magic‐angle spinning (MAS) (up to 60 kHz) at 21.1 T. These Rb‐ionophore complexes containing macrocycles such as benzo‐15‐crown‐5 and cryptand [2.2.2] are typical of organic Rb salts that exhibit very large 87 Rb quadrupole coupling constants (close to 20 MHz). We have also obtained static 87 Rb NMR spectra for these two compounds and determined both 87 Rb quadrupole coupling and chemical shift tensors. The experimental 87 Rb NMR tensor parameters are compared with those obtained by quantum chemical computations. Our results demonstrate that the combination of fast MAS (60 kHz or higher) and a high magnetic field (21.1 T or higher) is sufficient to produce high‐quality solid‐state 87 Rb NMR spectra for organic Rb solids at the natural abundance level. We anticipate that, with additional 87 Rb isotope enrichment (up to 99%), the sensitivity of solid‐state 87 Rb NMR will be 400 times higher than 39 K NMR, which makes the former an attractive surrogate probe for studying K + ion binding in biological systems.