The factors affecting the electrochemiluminescence of Tris(2,2'-bipyridyl)ruthenium(II)/tertiary amines

Factors affecting tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)(3)(2+))/tertiary amine electrochemiluminescence (ECL) were investigated in the present work with several tertiary amines as coreactants. Some new phenomena different to those of traditional Ru(bpy)(3)(2+)/tripropylamine were observed, such as the different responses of different coreactants to the hydrophobic nature of the working electrode and the ECL emission of triethanolamine at 0.85 V ne pK(a) value (acid dissociation constant) for the deprotonation of tertiary amine group in the coreactant molecules and solubility of coreactants affect the ECL profiles vs. electrolyte pH. Moreover, the solubility of coreactants is also related to the ECL response to the addition of surfactants and electrode hydrophobic nature. Investigation of the effects of molecular structures indicated that molecules restricting the formation of the trigonal planar structure of the active radical in the electrooxidation procedure resulted in low ECL emission. The behaviors of hydroxyl and carboxylic group as substituents of alpha-carbon are also totally different to the traditional opinions about the ECL from Ru(bpy)(3)(2+)/tertiary amines.