Selective liquid-phase molecular sieving via thin metal–organic framework membranes with topological defects

Separating fine and similarly sized targets in liquids is a crucial but challenging task. Although current membranes have the potential to be sustainable and energy-efficient options, their molecular selectivity and durability remain limited. Here we report robust and accurate molecular-sieving membranes created through the topological design of a Zr-based metal–organic framework, namely UiO-66, for use in durable liquid-phase separations. Our findings reveal that crystallizing UiO-66 using a bimetallic method yields distinctive reo-topology frameworks with periodic missing-cluster defects. We crystallize reo-UiO-66 into thin polycrystalline membranes that exhibit improved and robust performance, lasting for over 1,500 h. The modified Ferry transport model provides a quantitative description of solute rejection from the polycrystalline membrane. Multiple molecular-sieving experiments recognize excellent membrane selectivity to accurately discriminate fine complex mixtures with molecular weights below 350 g mol⁻¹. In addition, our membrane demonstrates promise in purifying and recovering high-value pharmaceuticals and catalysts. This work paves the way for developing polycrystalline membrane technology for the sustainable separation of chemical mixtures in liquids.