Dynamic regulation of ion transport through a bis(1,3-propanediol)-based channel via allosteric azobenzene photoswitching

The transportation of ions across cell membranes is vital in biological functions and is frequently controlled by external triggers like light, ligands, and voltage. Synthetic ion transport systems, particularly those featuring gating mechanisms, have attracted considerable interest. In this research, we engineered self-assembled barrel rosette ion channels using a photoresponsive azobenzene integrated at an allosteric site. Morphological studies verified more effective self-assembly of the trans form in contrast to the cis form. The restricted self-assembly of the cis form can be ascribed to the nonplanar structure of cis azobenzene moieties, which inhibits favorable π-π stacking interactions. The ion transport studies demonstrated the formation of ion channels by the trans form with anion antiport as the primary transport mechanism. In contrast, the cis form exhibited lower efficiency. Based on these observations, dynamically gated ion transport was achieved by employing two sets of electromagnetic radiations at 365 nm and 450 nm, respectively. Molecular dynamics simulation studies demonstrated that the channel formed by assembling trans monomers exhibited greater stability when compared to the channel formed by cis monomers. Additionally, the trans channel was found to recognize and transport chloride effectively.