Rich Polymorphism of a Metal–Organic Framework in Pressure–Temperature Space

We present an in situ powder X-ray diffraction study on the phase stability and polymorphism of the metal–organic framework ZIF-4, Zn­(imidazolate)2, at simultaneous high pressure and high temperature, up to 8 GPa and 600 °C. The resulting pressure–temperature phase diagram reveals four, previously...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2019-06, Vol.141 (23), p.9330-9337
Main Authors: Widmer, Remo N, Lampronti, Giulio I, Chibani, Siwar, Wilson, Craig W, Anzellini, Simone, Farsang, Stefan, Kleppe, Annette K, Casati, Nicola P. M, MacLeod, Simon G, Redfern, Simon A. T, Coudert, François-Xavier, Bennett, Thomas D
Format: Article
Language:English
Subjects:
Chemical Sciences
Material chemistry
or physical chemistry
Theoretical and
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Summary:We present an in situ powder X-ray diffraction study on the phase stability and polymorphism of the metal–organic framework ZIF-4, Zn­(imidazolate)2, at simultaneous high pressure and high temperature, up to 8 GPa and 600 °C. The resulting pressure–temperature phase diagram reveals four, previously unknown, high-pressure–high-temperature ZIF phases. The crystal structures of two new phasesZIF-4-cp-II and ZIF-hPT-IIwere solved by powder diffraction methods. The total energy of ZIF-4-cp-II was evaluated using density functional theory calculations and was found to lie in between that of ZIF-4 and the most thermodynamically stable polymorph, ZIF-zni. ZIF-hPT-II was found to possess a doubly interpenetrated diamondoid topology and is isostructural with previously reported Cd­(Imidazolate)2 and Hg­(Imidazolate)2 phases. This phase exhibited extreme resistance to both temperature and pressure. The other two new phases could be assigned with a unit cell and space group, although their structures remain unknown. The pressure–temperature phase diagram of ZIF-4 is strikingly complicated when compared with that of the previously investigated, closely related ZIF-62 and demonstrates the ability to traverse complex energy landscapes of metal–organic systems using the combined application of pressure and temperature.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.9b03234