Spectroelectrochemical Studies of Ru(bpy)32+ at the Water/1,2-Dichloroethane Interface

The application of differential cyclic voltfluorometry in total internal reflection (TIR) geometry to the study of Ru(bpy) 3 2+ transfer at the water/1,2-dichloroethane (DCE) interface has been studied. The emission spectra of Ru(bpy) 3 2+ in bulk water, in bulk DCE, and at various applied potentials at the water/DCE interface have also been measured. Both techniques allow discrimination between Ru(bpy) 3 2+ in water and Ru(bpy) 3 2+ in DCE. Also, the quenching of the excited state of aqueous Ru(bpy) 3 2+, irradiated in TIR geometry, at the water/DCE interface by tetracyanoquinodimethane (TCNQ), dissolved in the adjacent organic phase, has been studied using time-resolved luminescence spectroscopy. Electrochemically controlled experiments were then conducted at applied interfacial potentials, and the only quenching observable was attributed to the transfer of Ru(bpy) 3 2+ into the DCE phase by direct comparison with the voltfluorogram measured during the same experiment. At applied potentials where Ru(bpy) 3 2+ was maintained principally in the aqueous phase, no heterogeneous electron transfer could be observed by time-resolved luminescence spectroscopy in TIR geometry.