Electrochemically modulated photoluminescence at the chemically derivatized electrode: [CdRu(CN)₄(bpy)]^0/+ modified electrodes

A CdRu(bpy)(CN)₄ surface derivative can be formed on SnO₂ and Pt electrodes by soaking a cadmium-plated electrode in an aqueous solution of K₂Ru(bpy)(CN)₄. Diffuse reflectance FTIR confirms the formation of the surface species. Electrodes modified in this manner are found to be luminescent. The emission intensity and excited-state lifetime can be electrochemically modulated, since they are dependent on the ruthenium oxidation state. The derivatizing-layer lifetime can be fit to the Stern-Volmer equation, suggesting a bimolecular quenching process. The rate constant for this process is affected by the type of supporting electrolyte cation present. Forming a [CdFe(CN)₆]^2-/- surface derivative on a SnO₂ electrode prior to derivatization with [CdRu(bpy)(CN)₄]^0/+, improves the heterogeneous charge-transfer rates. Variation in the alkali cation intercalated into the [CdFe(CN)₄]^2- layer prior to reaction with K₂Ru(bpy)(CN)₄ leads to major differences in overlayer structure, suggesting a relationship between derivative structure and charge-transfer dynamics.