Clathrate structure determination by combining crystal structure prediction with computational and experimental ¹²⁹Xe NMR spectroscopy

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>We present an approach for the structure determination of clathrates using NMR spectroscopy of enclathrated xenon to select froma set of predicted crystal structures. Crystal structure prediction methods have been used to generate an ensemble of putative structures of <em>o</em>- and <em>m</em>-fluorophenol, whose previously unknown clathrate structures have been studied by ¹²⁹Xe NMR spectroscopy. The high sensitivity of the ¹²⁹Xe chemical shift tensor to the chemical environment and shape of the crystalline cavity makes it ideal as a probe for porous materials. The experimental powder NMR spectra can be used to directly confirm or reject hypothetical crystal structures generated by computational prediction, whose chemical shift tensors have been simulated using density functional theory. For each fluorophenol isomer we find one predicted crystal structure whose measured and computed chemical shift tensors agree within experimental and computational error margins and these are thus proposed as the true fluorophenol xenon clathrate structures.</p></div>