Solid-state NMR spectra of paramagnetic silica-based materials: observation of 29Si and 27Al nuclei in the first coordination spheres of manganese ions
✍ Scribed by Vladimir I. Bakhmutov; Boris G. Shpeizer; Abraham Clearfield
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 348 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.1866
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✦ Synopsis
Abstract
Some silica‐based solids, prepared by the sol/gel method in the presence of high Mn^2+^ concentrations, have been characterized by the ^29^Si, ^27^Al MAS NMR spectra and ^29^Si T~1~ measurements. The single‐pulse ^29^Si and ^27^Al MAS NMR spectra have shown broad spinning sideband patterns that are interpreted in terms of anisotropic bulky magnetic susceptibility (BMS) and dipole‐field effects. In the absence of paramagnetic isotropic shifts, the ^29^Si and ^27^Al nuclei observed in the single‐pulse NMR spectra have been assigned to nuclei remote from paramagnetic centers. It has been demonstrated that the ^29^Si and ^27^Al nuclei, which are in the vicinity of the manganese ions, can be detected by the Hahn‐echo MAS NMR experiments at different carrier frequencies. Copyright © 2006 John Wiley & Sons, Ltd.