A comparison of microcrystal electron diffraction and X-ray powder diffraction for the structural analysis of metal-organic frameworks.

Abstract

This study successfully implemented microcrystal electron diffraction (microED) and X-ray powder diffraction (XRPD) for the crystal structure determination of a new phase, TAF-CNU-1, Ni(C₈H₄O₄)·3H₂O, solved by microED from single microcrystals in the powder and refined at the kinematic and dynamic electron diffraction theory levels. This nickel metal-organic framework (MOF), together with its cobalt and manganese analogues with formula M(C₈H₄O₄)·2H₂O with M = Mn^II or Co^II, were synthesized in aqueous media as one-pot preparations from the corresponding hydrated metal chlorides and sodium terephthalate, as a promising 'green' synthetic route to moisture-stable MOFs. The crystal structures of the two latter materials have been previously determined ab initio from X-ray powder diffraction. The advantages and disadvantages of both structural characterization techniques are briefly summarized. Additional solid-state property characterization was carried out using thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectroscopy.