Solvent-Free Synthesis of a new Perfluorinated MIL-53(Al) with a Genuine Temperature-Induced Breathing Effect

We report on the solvent-free synthesis of the perfluorinated analogue of the well-known breathing metal-organic framework MIL-53(Al), i.e., F4-MIL-53(Al), featuring tetrafluoroterephthalic acid as linker. The crystal structure was solved and refined from powder X-ray diffraction data and confirmed to be isoreticular with MIL-53(Al). In contrast to the MIL-53(Al) analogue, F4-MIL-53(Al) displays a peculiar breathing effect solely induced by the temperature and not by the desorption of molecules at increasing temperature. This unique behaviour is experimentally reported here for the first time.