Intrinsic Microporosity Integrates Fast Transport and Enantioselective Recognition in Chiral Polymer Membranes

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Abstract
The long-standing trade-off between enantioselectivity and permeability remains a central challenge in mem-brane-based chiral separation. Materials capable of strong chiral recognition often suffer from slow molecular transport, while highly permeable membranes generally exhibit limited enantioselectivity. Here, we show that intrinsic microporosity provides an effective route to alleviate this limitation. We construct a pair of enantio-meric polymers of intrinsic microporosity (HBIN-Is) through the one-step polymerization of BINOL and isatin. The resulting polymers combine rigid contorted backbones, permanent microporosity, and homochiral envi-ronments, enabling the formation of robust free-standing membranes. The membranes exhibit simultaneous high enantioselectivity and permeation flux toward BINOL and Br-BINOL racemates, achieving enantiomeric excess values up to 97.7% together with high fluxes around 0.38 mmol·m-2·h-1, among the highest reported for polymer-based chiral membranes. Adsorption experiments, density functional theory calculations, and non-covalent interaction analyses reveal that chiral discrimination originates from cooperative hydrogen-bonding and stereochemically matched host–guest interactions within the microporous framework. This work identifies intrinsic microporosity as a powerful design principle for integrating molecular recognition and rapid transport in chiral membranes and provides a scalable platform for energy-efficient enantiomer separation.

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