Green Electrochemiluminescence from Ortho-Metalated Tris(2-phenylpyridine)iridium(III)

Abstract

The electrochemiluminescence (ECL) of Ir(ppy)3 (ppy = 2-phenylpyridine) is reported in acetonitrile (CH3CN), mixed CH3CN/H2O (50:50 v/v), and aqueous (0.1 M KH2PO4) solutions with tri-n-propylamine as an oxidative−reductive coreactant. ECL efficiencies (φecl, photons emitted per redox event) of 0.000 92 in aqueous, 0.0044 in mixed, and 0.33 in CH3CN solutions for Ir(ppy)3 were obtained using Ru(bpy)32+ (bpy = 2,2‘-bipyridine) as a relative standard (φecl = 1). Photoluminescence (PL) efficiencies of 0.039, 0.050, and 0.069 were obtained in aqueous, mixed, and acetonitrile solutions, respectively, compared to Ru(bpy)32+ (φem = 0.042). The ECL spectra were identical to photoluminescence spectra (λmax ≅ 517 nm), indicating formation of the same metal-to-ligand (MLCT) excited states in both ECL and PL. The ECL is linear over several orders of magnitude in mixed and acetonitrile solution with theoretical detection limits (blank plus three times the standard deviation of the noise) of 1.23 nM in CH3CN and 0.23 μM in CH3CN/H2O (50:50 v/v).

Department(s)

Chemistry and Biochemistry

Document Type

Article

DOI

https://doi.org/10.1021/ac0111513

Keywords

solution chemistry, photoluminescence, solvents, chemiluminescence, excited states

Publication Date

2002

Journal Title

Analytical chemistry

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