Photoresponsive and Reusable Chiral Metal-Organic Framework Hybrid Nanochannel Membrane for Drug Enantioseparation

Chiral metal-organic framework (CMOF)-based porous membrane materials have attracted great interest in the enantioseparation community. Despite remarkable progress, it remains a challenge to obtain functional membranes with a tunable enantioselectivity. Herein, we report on a photoresponsive and enantioselective nanoporous membrane prepared by in situ growth of azobenzene (Azo)-functionalized UiO-66 (UiO-66-Azo) onto anodic aluminum oxide (AAO) membrane. Tethering β-cyclodextrin (β-CD) to UiO-66-Azo/AAO via host-guest interaction created an efficient chiral hybrid nanochannel membrane, UiO-66-Azo@β-CD/AAO. The azo-rendered UV-vis photoswitch function could facilely realize assembly and disassembly of enantio-binding units, β-CD, enabling the enantioseparation capacity to refresh and improve the enantiomeric gating efficiency, and importantly, making the chiral membrane reusable. We demonstrated the utility of the chiral membrane by separation of S/R-naproxen enantiomer, gaining excellent enantioseparation performance, with an enantiomeric excess (ee) of 81.5% for S/R-naproxen. Molecular dynamics simulations were in agreement with the experimental findings. This work provides a low-cost and easy-to-mass-produce chiral nanochannel membrane for enantiomeric separation applications.