Pressure-Induced Structural Transitions in Zeolitic Imidazolate Frameworks

The structural evolution of ZIFs as a function of CO2 and N2 adsorption/desorption will be investigated using in situ neutron total scattering. ZIFs exhibit conformational and phase transitions that increase the uptake of guest molecules. Phase-to-phase transformations due to pressure and gate-opening (adsorption) and -closing (desorption) have been observed in the short- and long-range structure of ZIF-8 and ZIF-7 at moderate and high pressures. In this study, we will follow the structural transitions of the two ZIFs at different pressures (1.35 – 10 bar) of CO2, N2, and an equimolar CO2/N2 mixture. By using total scattering, we aim to elucidate the interplay between local adsorption phenomena and long-range structure. The mechanistic information obtained from this study will enable the design and development of more effective MOFs for gas adsorption. We also hope to isolate the ideal process conditions for trapping guest molecules and selective adsorption, which are essential to carbon capture, utilisation, and storage technologies.