Abstract

Harvesting visible light by means of nano-scale solar antennae will contribute to advancement in solar energy conversion. Optimization in supramolecular antennae design cannot be achieved without knowledge of intramolecular energy transfer rate constants. In my work, a series of asymmetric MLCT (Metal to Ligand Charge Transfer) Rhenium(I) bimetallic complexes have been prepared in order to study intramolecular energy transfer rates. These bimetallic complexes are in the form of [Re(CO)₃(bpy)(μ-dppene)Re(CO) ₂(bpy)(L)]²⁺ (where bpy is 2,2'-bipyridine; dppene is trans-1,2-bis(diphenylphosphino)ethylene; and L is a [Re(CO) ₃(bpy)(μ-dppene)]⁺ capping unit, a triphenylphosphine, a methyldiphenylphosphine, a triphenylphosphite, or a trimethylphosphite ligand). Determination of rate constants is accomplished by the use of steady-state Stern-Volmer (SV) quenching of emission in the presence of a competitive intermolecular energy transfer quencher. It has been found that intramolecular energy transfer rates for this series of complexes vary as a function of the thermodynamic driving force. This is the first time a SV technique has been used to measure intramolecular energy transfer rate constants.