Porous organic cage mixed matrix membranes for efficient enantioseparation

Mixed matrix membranes (MMMs) based on homochiral microporous materials have emerged as a promising approach for enantioselective separation. However, constructing MMMs for achieving efficient enantioselective separation at a high feed concentration still remains a great challenge due to the suboptimal interfacial compatibility. Here, we employ soluble porous organic cages (POCs) of intrinsic chiral sites as fillers to fabricate MMMs devoid of interfacial defects, exhibiting fast and selective enantioseparation for racemic 2-phenylpropionic acid with a flux of 2.93×10-3 mol m-2 h-1 and an enantiomeric excess (ee) value up to 100% at a high concentration of 0.1 mol L-1. The POC-based MMMs demonstrate a long-term operation stability with a low ee decline rate of 0.56% h-1. This work reveals the imperative role of the microporous chiral environment in POCs for the enantioselective recognition and furnishes guidelines for the construction of POC-based membranes for efficient chiral separation. Mixed matrix membranes using homochiral microporous materials can be used for enantioselective separations, though optimizing selectivity at high feed concentration is challenging. Here the authors use porous organic cages for separations with high selectivity at high concentrations.