Electrogenerated chemiluminescence of tris (2-phenylpyridine) iridium (III) in water, acetonitrile and trifluorethanol

Robinson Wesley, MSU Graduate Student
Mark M. Richter, Missouri State University

Abstract

The spectroscopic, electrochemical and coreactant electrogenerated chemiluminescence (ECL) properties of Ir(ppy)3 (where ppy"‰="‰2-phenylpyridine) have been obtained in aqueous buffered (KH2PO4), 50 : 50 (v/v) acetonitrile"“aqueous buffered (MeCN"“KH2PO4) and 30% trifluoroethanol (TFE) solutions. Tri-n-propylamine was used as the oxidative-reductive ECL coreactant. The photoluminescence (PL) efficiency (Ï•em) of Ir(ppy)3 in TFE (Ï•em"‰â‰ˆ"‰0.029) was slightly higher than in 50 : 50 MeCN"“KH2PO4 (Ï•em"‰â‰ˆ"‰0.0021) and water (Ï•em"‰â‰ˆ"‰0.00016) compared to a Ru(bpy)32+ standard solution in water (Φem"‰â‰ˆ"‰0.042). PL and ECL emission spectra were nearly identical in all three solvents, with dual emission maxima at 510 and 530"‰nm. The similarity between the ECL and PL spectra indicate that the same excited state is probably formed in both experiments. ECL efficiencies (Ï•ecl) in 30% TFE solution (Ï•ecl"‰="‰0.0098) were higher than aqueous solution (Ï•ecl"‰="‰0.00092) system yet lower than a 50% MeCN"“KH2PO4 solution (Ï•ecl"‰="‰0.0091). Copyright © 2014 John Wiley & Sons, Ltd.