Photocurrent Generation from Ru(bpy)32+ Immobilized on Phospholipid/Alkanethiol Hybrid Bilayers

A new photocurrent-generation system based on Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) tethered oil phospholipid/alkanethiol hybrid bilayers in aqueous media is reported. The construction of such a system is straightforward. First, a self-assembled monolayer (SAM) of alkanethiol is formed oil gold. and separately, liposomes containing Ru(bpy)(3)(2+)-conjugated dioleoylphosphoethanolamine (DOPE) are prepared by extrusion. Subsequent exposure of the Ru(bpy)(3)(2+)-containing liposome solution to the preformed SAM induces the addition of a monolayer of phospholipids on top of the SAM and thereby the immobilization of a Ru(bpy)(3)(2+) layer on the gold electrode, Either anodic or cathodic photocurrent generation call be obtained, when ascorbate (anodic) or methyl violgen/oxygen (cathodic) is used its a sacrificial electron donor/acceptor, respectively. Light conversion quantum efficiencies of 0.84% (anodic) and 0.21% (cathodic) were obtained under blue light (lambda = 470 +/- 20 nm) irradiation. The photocurrent-generation and electron-transfer mechanisms of this new system as well as its potential usefulness in fundamental photoconversion studies are discussed.