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

Remo N. Widmer, Giulio I. Lampronti, Siwar Chibani, Craig W. Wilson, Simone Anzellini, Stefan Farsang, Annette K. Kleppe, Nicola P. M. Casati, Simon G. MacLeod, Simon A. T. Redfern, Francois-Xavier Coudert, Thomas D. Bennett*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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 degrees 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.

Original languageEnglish
Pages (from-to)9330-9337
Number of pages8
JournalJournal of the American Chemical Society
Volume141
Issue number23
Early online date22 May 2019
DOIs
Publication statusPublished - 12 Jun 2019

Keywords

  • ZEOLITIC IMIDAZOLATE FRAMEWORKS
  • TOTAL-ENERGY CALCULATIONS
  • INDUCED AMORPHIZATION
  • MOLECULAR-DYNAMICS
  • CRYSTAL-STRUCTURE
  • STATE
  • ADSORPTION
  • TRANSITIONS
  • MONOLITHS
  • GLASSES

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