Ion‐Permselective Porous Organic Cage Membranes

Porous organic cages (POCs) have emerged as a distinct class of molecular porous materials featuring precisely tunable pore architectures and exceptional solution processability, positioning them as promising platforms for membrane-based ion separation. Their unique ability to synergistically combine structural confinement with tunable ion-channel interactions enables the selective separation of ions with closely similar sizes and physicochemical properties. This review provides a systematic overview of recent advances in POC-based ion separation membranes, with an emphasis on molecular design, membrane fabrication, interfacial engineering, and the underlying separation mechanisms. Furthermore, it offers critical insights into emerging design principles and key challenges for achieving high-performance membranes, thereby establishing a conceptual framework for the development of next-generation ion separation systems.