Efficient green-colored electrochemiluminescence from cyclometalated iridium(III) complex

The spectroscopy, electrochemistry, and electrochemiluminescence (ECL) of cyclometalated iridium(III) bis(2-(p-tolyl)pyridinato-N, C-2') (picolinate) [(tpy)(2)lr(pico)] was investigated. (tpy)(2)lr(pico) shows high photoluminescence efficiency (Phi(PL) = similar to 0.31) and quasi-reversible redox behaviors in acetonitrile solution. Intense green ECL was observed from all three modes of ECL generation (annihilation, oxidative-reduction, and reductive-oxidation). Relative ECL efficiencies with or without coreactants from (tpy)(2)lr(pico) were estimated using Ru(bpy)(3)(2+) (bpy, 2,2'-bipyridine) as a relative standard. Typically, in the reductive-oxidation process with peroxodisulfate (S2O82-), (tpy)(2)lr(pico) produces 8-fold more efficient ECL at approximately 531 nm than Ru(bpy)(3)(2). This efficient green ECL indicates potential for the development of multicolored ECL analysis in addition to standard Ru(bpy)(3)(2+) systems. (C) 2011 Elsevier Ltd. All rights reserved.