INVESTIGATION OF RU(BPY)3(2+)/NAFION(R) FILM COATED ON ELECTRODES STUDIED USING INSITU SPECTROCYCLIC VOLTAMMETRY AND PHOTOLUMINESCENCE

The effects of pretreatment of cast Nafion(R) films on the redox characteristics of Ru(bpy)3(2+) (bpy = 2,2'-bipyridine) incorporated into the films were studied by in-situ spectrocyclic voltammetry (SCV) and photoluminescence. A water-soaked (W-type) Nafion film showed an efficient ability to adsorb Ru(bpy)3(2+), While an air-dried (D-type) Nafion film exhibited a slow exchange and a low degree of adsorption. The electroactive fraction of the ruthenium complex incorporated into the W-type films, measured by in-situ SCV, was higher (ca. 80%) than the value (ca. 40%) observed in the D-type films, suggesting the presence of a different microstructure for the incorporation of the complex after the pretreatment of these films. The emission lifetime was measured and the distribution of the ruthenium complex in the films was demonstrated. The emission lifetime of the ruthenium complex incorporated into the W-type film was longer (ca. 1000 ns) than that (ca. 600 ns) observed in the D-type film. The emission was discussed in comparison with the emission in other matrices. These results indicated an increase in the hydrophilic regions of the cast film after water-soaking pretreatment. A model based on the distribution of the electroactive species between hydrophilic and hydrophobic regions was proposed to explain the results.