Mimicking Photosystem I with a Transmembrane Light Harvester and Energy Transfer‐Induced Photoreduction in Phospholipid Bilayers

Abstract

Photosystem I (PS I) is a transmembrane protein that assembles perpendicular to the membrane, and performs light harvesting, energy transfer, and electron transfer to a final, water-soluble electron acceptor. We present here a supramolecular model of it formed by a bicationic oligofluorene 1(2+) bound to the bisanionic photoredox catalyst eosin Y (EY2-) in phospholipid bilayers. According to confocal microscopy, molecular modeling, and time dependent density functional theory calculations, 1(2+) prefers to align perpendicularly to the lipid bilayer. In presence of EY2-, a strong complex is formed (K-a=2.1 +/- 0.1x10(6) m(-1)), which upon excitation of 1(2+) leads to efficient energy transfer to EY2-. Follow-up electron transfer from the excited state of EY2- to the water-soluble electron donor EDTA was shown via UV-Vis absorption spectroscopy. Overall, controlled self-assembly and photochemistry within the membrane provides an unprecedented yet simple synthetic functional mimic of PS I.Metals in Catalysis, Biomimetics & Inorganic Material