Surfactant chain length effects on the light emission of tris(2,2′-bipyridyl)ruthenium(II)/tripropylamine electrogenerated chemiluminescence

The effects of nonionic surfactant chain length on the properties of tris(2,2'-bipyridyl)ruthenium(D) (Ru(bpy)(3)(2+) where bpy = 2,2'-bipyridine) electrochemiluminescence (ECL) have been investigated. The electrochemistry, photophysics, and ECL of Ru(bpy)(3)(2+) in the presence of a series of nonionic surfactants; are reported (Triton X-100, 114, 165, 405, 305, and 705-70). These surfactants differ in the number of poly(ethylene oxide) units incorporated into the surfactant molecule. The anodic oxidation of Ru(bpy)32+ produces ECL in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (greater than or equal to5-fold) and TPrA oxidation current (greater than or equal to2-fold) have been observed in surfactant media. Slight decreases in ECL intensity are observed as the chain length of the nonionic surfactant increases. The data supports adsorption of sutfactant on the electrode surface, thus facilitating TPrA and Ru(bpy)(3)(2+) oxidation and leading to higher ECL efficiencies.