Controlling lattice flexibility in MOF film by structural transformation

We recently developed a heat treatment based post-synthetic treatment on ZIF-8 membranes, leading to dissociation of methyl group from the linker (2-methylimidazole) and a formation of linker vacancy defects, which manifests into the shrinkage of lattice parameter by up to 1%. As a result, unprecedented H2/CH4, CO2/CH4, and CO2/N2 selectivities of 170, 32.5, and 29.3, respectively, were achieved. With this significant effect of the heat treatment of ZIF-8 films on the gas-diffusivity, this proposal aims to gain in-depth understanding of the thermal-treatment led structural transformation in MOFs. We seek to decouple strain in the supported polycrystalline film from the lattice shrinkage and generate high precision data correlating lattice parameter to gas diffusivity. Further, we seek to understand whether or not such lattice parameter changes will take place by RHT-led controlled linker modification in a wider range of MOFs (ZIF-67, ZIF-90, ZIF-7) to tune the gas diffusivity.