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Electrogenerated Chemiluminescence 69: The Tris(2,2‘-bipyridine)ruthenium(II), (Ru(bpy) 3 2+ )/Tri- n -propylamine (TPrA) System RevisitedA New Route Involving TPrA •+ Cation Radicals

2002; American Chemical Society; Volume: 124; Issue: 48 Linguagem: Inglês

10.1021/ja027532v

1943-2984

Wujian Miao, Jai-Pil Choi, Allen J. Bard,

Photochemistry and Electron Transfer Studies

The reaction occurring on electrooxidation of Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) and tri-n-propylamine (TPrA) leads to the production of Ru(bpy)(3)(2+) and light emission. The accepted mechanism of this widely used reaction involves the reaction of Ru(bpy)(3)(3+) and a reduced species derived from the free radical of the TPrA. However, this mechanism does not account for many of the observed features of this reaction. A new route involving the intermediacy of TPrA cation radicals (TPrA(*+)) in the generation of Ru(bpy)(3)(2+) was established, based on results of scanning electrochemical microscopy (SECM)-electrogenerated chemiluminescence (ECL) experiments, as well as cyclic voltammetry simulations. A half-life of approximately 0.2 ms was estimated for TPrA(*+) in neutral aqueous solution. Direct evidence for TPrA(*+) in this medium was obtained via flow cell electron spin resonance (ESR) experiments at approximately 20 degrees C. The ESR spectra of the TPrA(*+) species consisted of a relatively intense and sharp septet with a splitting of approximately 20 G and a g value of 2.0038.