Connecting defects and amorphization in UiO-66 and MIL-140 metal-organic frameworks: a combined experimental and computational study.

The mechanism and products of the structural collapse of the metal-organic frameworks (MOFs) , and upon ball-milling are investigated through solid state (13)C NMR and pair distribution function (PDF) studies, finding amorphization to proceed by the breaking of a fraction of metal-ligand bonding in each case. The amorphous products contain inorganic-organic bonding motifs reminiscent of the crystalline phases. Whilst the inorganic Zr6O4(OH)4 clusters of remain intact upon structural collapse, the ZrO backbone of the frameworks undergoes substantial distortion. Density functional theory calculations have been performed to investigate defective models of and show, through comparison of calculated and experimental (13)C NMR spectra, that amorphization and defects in the materials are linked.The manuscript was written through contributions of all authors. TDB conceived the initial project. T.D.B. acknowledges Trinity Hall (University of Cambridge) and Professor Anthony K. Cheetham for use of lab facilities. D.G.R. acknowledges the UK MRC for financial support. The authors acknowledge Diamond Light Source for the provision of synchrotron access to Beamline I15 (ex p. EE9691) and Philip A. Chater and Andrew Cairns for assistance with data collection. T.K.T. and C.M.D. thank the French National Research Agency (ANR project: HOPFAME ANR-13-BS07-0002-01) and the Foundation de l'Orangerie for funding. The calculations have been performed using the HPC resources from GENCI (CINES/TGCC/IDRIS) through Grant (2015-097343 and -091461). B.B., B.V.d.V. and D.D.V . gratefully acknowledge the FWO for funding (aspirant grant).This is the final version of the article. It was first available from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5CP06798