Light-induced charge separation in a donor–chromophore–acceptor nanocomposite poly[TPA-Ru(tpy)2]@ZnO

Abstract

The synthesis and characterisation of a new donor–chromophore–acceptor system based on poly(vinyltriphenylamine) as the electron donor and a glycine-functionalised bis(2,2′;6′,2′′-terpyridine)ruthenium(II) complex acting both as a chromophore and as an anchor group attached to ZnO nanorods as the electron acceptor are described. The TPA-containing block copolymer was synthesised by Reversible Addition Fragmentation Chain Transfer (RAFT) polymerisation and the ruthenium complex glycine conjugates prepared by Solid Phase Peptide Synthesis (SPPS) were attached via post-polymerisation esterification. GPC, NMR, IR and UV-Visible spectroscopy were used to characterise the multifunctional chromophore–donor polymer. Zinc oxide nanorods were functionalised with the block copolymer by multisite adsorption via the glycine COOH groups. The functionalised nanoparticles were well dispersible in organic solvents. Photoluminescence studies showed a complete quenching of the phosphorescence of the ruthenium chromophore (³MLCT state). Kelvin probe force microscopy (KPFM) was used to confirm that under continuous excitation of the Ru^II complex (¹MLCT) the polymer corona develops a positive charge and thus efficient charge separation between ZnO and the polymer is achieved.