Using 17O solid-state NMR and first principles calculation to characterise structure and dynamics in inorganic framework materials

Abstract

The use of solid-state ¹⁷O NMR to determine local chemical environment and to characterise oxygen dynamics is illustrated in studies of zirconium tungstate, ZrW₂O₈, and tungsten oxide, WO₃. Simple 1D magic-angle spinning (MAS) NMR allows the chemical environments in ZrW₂O₈to be readily characterised, and the use of a combination of one- and two-dimensional experiments to characterise oxygen dynamics in its cubic phase is reviewed. Combining local information about structure and dynamics from NMR with long-range structural information from diffraction allows a comprehensive picture of the material to be developed. Recent work is described that uses first principles calculation of NMR parameters to probe subtle asymmetries in the WO₆octahedra that form the structural motif in WO₃. NMR is shown to be a highly sensitive probe of local structure, allowing different models derived from high-quality neutron diffraction studies to be distinguished. The density functional theory (DFT) calculations allow clear correlations between ¹⁷O chemical shifts and distortions of the structure to be established. Copyright © 2007 John Wiley & Sons, Ltd.