Photoinduced electron transfer across phospholipid bilayers in anaerobic and aerobic atmospheres

In natural photosynthesis, light-driven electron transfer across the thylakoid membrane enables efficient charge separation and the confinement of reaction spaces for generating NADPH and CO2 and oxidation of water. These reactions are complementary redox reactions and require different reaction conditions for optimal performance. However, current artificial photosynthesis studies only take place in the bulk and are sensitive towards oxygen and air, which limits their applicability under aerated and water-splitting conditions. Herein, we report light-driven electron transfer across a lipid bilayer membrane of liposome vesicles via a rigid oligoaromatic molecular wire that allows to electronically connect an oxidation and reduction reaction which are spatially separated by the membrane. The molecular wire has a simple, symmetric, easy-to-synthesize design based on benzothiadiazole and fluorene units and absorbs in the visible spectrum which makes it suitable for solar energy conversion. The model reactions in this study are light-driven NADH oxidation on one side of the membrane and light-driven reduction of an organic water-soluble dye in the bulk phase of liposomes. Additionally, the system is active in both aerobic and anaerobic atmospheres, rendering it ideal for aerobic conditions or reactions that produce oxygen such as solar-driven water splitting and artificial photosynthesis applications.