In situ powder X-ray diffraction of analogues of MIL-53(Al) with increasing degree of fluorination

We propose an in situ PXRD study on AlIII-based MOFs with MIL-53 topology, where the terephthalate linker is functionalized with 1–4 fluorine atoms. The parent H4-MIL-53(Al) framework undergoes a “breathing” transition upon activation and/or gas sorption, while its perfluorinated analogue F4-MIL-53(Al) retains this flexibility but with markedly different characteristics. This indicates that fluorination of the linker strongly influences the energetics of the breathing phenomenon. The experiment aims to elucidate the structural phase transitions of fluorinated Fx-MIL-53(Al) (x = 1–3) upon CO2 adsorption, to quantitatively assess the role of fluorine in determining their structural evolution.