Photoresponsive Molecular Switch for Regulating Transmembrane Proton-Transfer Kinetics

To control proton delivery across biological membranes, we synthesized a photoresponsive molecular switch and incorporated it in a lipid layer. This proton gate was reversibly activated with 390 nm light (<i>Z</i>-isomer) and then deactivated by 360 nm irradiation (<i>E</i>-isomer). In a lipid layer this stimuli responsive proton gate allowed the regulation of proton flux with irradiation to a lipid-buried O<sub>2</sub> reduction electrocatalyst. Thus, the catalyst was turned on and off with the <i>E</i>-to-<i>Z</i> interconversion. This light-induced membrane proton delivery system may be useful in developing any functional device that performs proton-coupled electron-transfer reactions.