Dynamic regulation of ion transport through a bis(1,3-propanediol)-based channel <i>via</i> 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 <i>trans</i> form in contrast to the <i>cis</i> form. The restricted self-assembly of the <i>cis</i> form can be ascribed to the nonplanar structure of <i>cis</i> azobenzene moieties, which inhibits favorable π-π stacking interactions. The ion transport studies demonstrated the formation of ion channels by the <i>trans</i> form with anion antiport as the primary transport mechanism. In contrast, the <i>cis</i> form exhibited lower efficiency. Based on these observations, dynamically gated ion transport was achieved by employing two sets of electromagnetic radiation at 365 nm and 450 nm, respectively. Molecular dynamics simulation studies demonstrated that the channel formed by assembling <i>trans</i> monomers exhibited greater stability when compared to the channel formed by <i>cis</i> monomers. Additionally, the <i>trans</i> channel was found to recognize and transport chloride effectively.