Dual Luminescence and Long-Lived Charge-Separated States in Donor-Acceptor Assemblies Based on Tetrathiafulvalene-Fused Ruthenium(II)-Polypyridine Complexes

Abstract

The creation of long-lived charge-separated states in donor–acceptor assemblies has been the goal of many studies aimed at mimicking the primary processes in photosynthesis. Here we present such assemblies based on tetrathiafulvalene (TTF) as electron donor and a dipyridophenazine (dppz) unit as electron acceptor in the form of a fused ligand (TTF-dppz) coordinated to ruthenium(II) via the dipyrido coordination site and with 2,2?-bipyridine (bpy) as auxiliary ligand, namely [Ru(bpy)3?x(TTF-dppz)x]2+ (x = 1?3). For x = 2, irradiation into the metal to dppz charge transfer transition results in electron transfer from TTF to ruthenium, thus creating a charge-separated state best described by [(TTF+-dppz)Ru(dppz?-TTF)(bpy)]2+ with a lifetime of 2.5 ?s in dichloromethane.

Keywords

• Charge-separated states
• Intraligand charge transfer
• Metal-ligand-charge-transfer
• Ruthenium(ii)-polypyridine complexes
• Tetrathiafulvalene