Song, JianboPallach, RomanFrentzel-Beyme, LouisKolodzeiski, PascalKieslich, GregorVervoorts, PiaHobday, Claire L.Henke, Sebastian2024-03-062024-03-062022-02-04http://hdl.handle.net/2003/42380http://dx.doi.org/10.17877/DE290R-24216The high-pressure behaviour of flexible zeolitic imidazolate frameworks (ZIFs) of the ZIF-62 family with the chemical composition M(im)2−x(bim)x is presented (M2+=Zn2+, Co2+; im−=imidazolate; bim−=benzimidazolate, 0.02≤x≤0.37). High-pressure powder X-ray diffraction shows that the materials contract reversibly from an open pore (op) to a closed pore (cp) phase under a hydrostatic pressure of up to 4000 bar. Sequentially increasing the bim− fraction (x) reinforces the framework, leading to an increased threshold pressure for the op-to-cp phase transition, while the total volume contraction across the transition decreases. Most importantly, the typical discontinuous op-to-cp transition (first order) changes to an unusual continuous transition (second order) for x≥0.35. This allows finetuning of the void volume and the pore size of the material continuously by adjusting the pressure, thus opening new possibilities for MOFs in pressure-switchable devices, membranes, and actuators.enHigh-pressure crystallographyMechanical propertiesMetal-organic frameworksPhase transitionResponsive materials540Text