Crystalline, Amorphous, and Liquid Metal-Organic Frameworks at Non-Ambient Conditions
type: CreativeWork
description: Metal-organic frameworks (MOFs), in the traditional sense, are crystalline and microporous materials. MOFs are of incessant scientific interest due to their enormous potential as host structures for a range of chemical process applications, including molecular separation, catalytic reaction, and gas storage. In the course of investigating their physical and chemical properties, it was soon discovered how diverse the structural responses of these low-density materials are when, for example, heated or compressed. Such structural changes range from the simple loss of pore-occupying solvent molecules to intricate sequences of structural phase transitions. Some MOFs are also capable of forming glasses, i.e. dense amorphous structures, with chemical composition and short-range order that is reminiscent of their crystalline precursor. This generated a new area of research within the MOF discipline at the interface of glass science, supramolecular chemistry, and condensed matter physics. Here, two isotopological zeolitic imidazolate frameworks, ZIF-4 and ZIF-62, have been studied under the influence of a range of physical variables. Pressure- and temperatureinduced crystalline–amorphous and crystalline–crystalline phase transitions have been investigated using in-situ high-pressure/high-temperature powder X-ray diffraction and Raman spectroscopy. Furthermore, these transitions were also studied as a function of varying chemical composition of the ZIFs, as well as of dynamic variables such as heating- and compression-rate. The two ZIFs were shown to be related by a continuous solid solution and this chemical substitution was found to systematically control the high-temperature behaviour. Moreover, simultaneous heating and compression of the endmember compositions ZIF-4 and ZIF-62 up to 600 ◦C and 8 GPa resulted in strikingly different pressure-temperature phase diagrams. For ZIF-4, four, previously unknown, high-pressure-temperature polymorphs were found. The crystal structu…
abstract: Metal-organic frameworks (MOFs), in the traditional sense, are crystalline and microporous materials. MOFs are of incessant scientific interest due to their enormous potential as host structures for a range of chemical process applications, including molecular separation, catalytic reaction, and gas storage. In the course of investigating their physical and chemical properties, it was soon discovered how diverse the structural responses of these low-density materials are when, for example, heated or compressed. Such structural changes range from the simple loss of pore-occupying solvent molecules to intricate sequences of structural phase transitions. Some MOFs are also capable of forming glasses, i.e. dense amorphous structures, with chemical composition and short-range order that is reminiscent of their crystalline precursor. This generated a new area of research within the MOF discipline at the interface of glass science, supramolecular chemistry, and condensed matter physics. Here, two isotopological zeolitic imidazolate frameworks, ZIF-4 and ZIF-62, have been studied under the influence of a range of physical variables. Pressure- and temperatureinduced crystalline–amorphous and crystalline–crystalline phase transitions have been investigated using in-situ high-pressure/high-temperature powder X-ray diffraction and Raman spectroscopy. Furthermore, these transitions were also studied as a function of varying chemical composition of the ZIFs, as well as of dynamic variables such as heating- and compression-rate. The two ZIFs were shown to be related by a continuous solid solution and this chemical substitution was found to systematically control the high-temperature behaviour. Moreover, simultaneous heating and compression of the endmember compositions ZIF-4 and ZIF-62 up to 600 ◦C and 8 GPa resulted in strikingly different pressure-temperature phase diagrams. For ZIF-4, four, previously unknown, high-pressure-temperature polymorphs were found. The crystal structu…
author: Widmer, Remo Nico
language: en
keywords: Metal-organic frameworks, Diamond anvil cell, Non-ambient XRD
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/1f5456d5-0d10-40cc-a3f3-e4a502661afb/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2019-10-31
date modified: 2026-07-22T22:24:03Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.44846