Electrified Isoreticular Synthesis of Zeolitic Imidazolate Framework‐90 Membrane Through Self‐Templating for Tunable Gas Separations

Metal-organic frameworks (MOFs) are amenable to isoreticulation, which provides a handle to fine-tune the pore apertures and thus their gas separation capabilities as molecular-sieving membranes. Electrified synthesis is an emerging and scalable approach for fabricating MOF membranes, notable for its ultrafast efficiency under ambient conditions. This rapid growth, however, poses a critical challenge to achieving crystallinity during isoreticular synthesis as excessively fast reaction kinetics might lead to the formation of amorphous products lacking long-range order. Here, we present a self-templating approach to form in situ structure-directing subunits, guiding the ordered assembly at extreme kinetics. This strategy enables the electrified isoreticulation of zeolitic imidazolate framework-8 (ZIF-8) to ZIF-90 with slightly larger pore apertures. Compared to the parent ZIF-8 membrane, which exhibited a propylene permeance of 52 GPU and selectivities of 100-300, the isoreticular ZIF-90 membrane delivers a ninefold higher permeance of 467 GPU while retaining a robust propylene/propane selectivity of 24.