Photoelectron transfer between molecules adsorbed in restricted spaces

Abstract

The photophysics and photoelectron transfer reactions of metal complexes bound to anionic surfaces which provide restricted spaces in aqueous solutions have been investigated by steady state and time resolved luminescence spectroscopy. The electron transfer systems were generated by systematically variation of structures derived from the Ru (II) tris-bipyridyl family as electron donors and methyl viologens and other metal tris-bipyridyl complexes as electron acceptors. The structure of the bipyridyl ligand in the complex was varied with respect to its functionality, size and shape in order to provide electron donors of similar driving force for electron transfer, but of differing binding selectivity and dynamics. In the same vein, metal substitution, e.g., Co (III) for Ru (II), provides a family of acceptors whose structures may be readily varied systematically. In addition, the inherent chirality of the tris-bipyridyl complexes allows opportunities for investigation of enantiomeric selection in binding and in the electron transfer step. The anionic surfaces selected for these investigations include those provided by micelles polyelectrolyte polymers, DNA double helix and starburst dendrimers. However, only the latter two surfaces are considered in detail in this report.