Photoswitchable molecular assembly for controlled chloride transport across the lipid membranes

Inspired by nature, biomimetic photoregulated ion transporters have attracted great interest because of the spatial and temporal control over ion transport, in which photocontrollable anion transport remains a very challenging task. Herein, we demonstrate an anionophore AZC for photoregulating anion transport with a high selectivity for chloride over hydroxide across the lipid membranes. Our strategy is based on a well-designed bidentate iodo-triazole anion receptor equipped with an azobenzene moiety, which recognizes Cl- by C-I halogen bonding and C-H hydrogen bonding and switches its states in the lipid membranes from inactive aggregates to active single molecules through azobenzene photoisomerization, thereby achieving controllable Cl- transport. Compared with trans-AZC, cis-AZC exhibits much higher ion transport activity with an EC50 (the effective concentration required for 50% activity) value at 28 nM, which is one of the highest reported activities to date for halogen bonding anionophores. Finally, it allows the modulation of Cl- transport upon reversible photoisomerization of AZC using alternative ultraviolet and visible light irradiation. This work provides a new strategy for designing stimuli-responsive anion transporters and paves the way for potential applications in remotely controlled membrane transport and treatment of related diseases.