Characterization of electrochemiluminescent ruthenium(II) complexes containing 2,2'-bipyridyl and related ligands

Abstract

Ru (II) complexes contg. 2,2'-bipyridyl, 2-(2-pyridyl)-benzimidazole, 2-(2-pyridyl)-N-methyl-benzimidazole, 4-carboxymethyl-4'-methyl-2,2'-bipyridine, 4,4'-dimethylbipyridine, and 1,10-phenanthroline ligands were prepd. by using literature procedures or new synthetic approaches and used as electrochemiluminescent (ECL) materials. All the complexes were characterized and compared to the known tris(2,2'-bipyridyl)ruthenium(II) complex in terms of electrochem. redox potential, and relative ECL intensity. The ECL emission produced by the reaction between electrooxidized Ru3+ species and tripropylamine as a reductant were measured in a static system or flow injection anal. where the glassy C electrode or dual Pt electrode were used as a working electrode with a potential of +1.3 V vs. Ag/AgCl (3 M NaCl) ref. electrode. ECL was obsd. for a large no. of Ru(II) complexes having 4-carboxymethyl-4'-methyl-2,2'-bipyridine, 4,4'-dimethylbipyridine, and 1,10-phenanthroline ligands. There was a good correlation between the obsd. ECL intensity and the donor ability of α-diimine ligands. As the donor ability of the ligand increases, the ECL intensity of the Ru(II) complex decreases. [on SciFinder(R)]