Electrogenerated Chemiluminescence of the Tris(2,2′-bipyridine)ruthenium(II)/Tri-n-propylamine (TPrA) System: Crucial Role of the Long Lifetime of TPrA•+ Cation Radicals Suggested by Electrode Surface Effects
Electrogenerated Chemiluminescence of the Tris(2,2′-bipyridine)ruthenium(II)/Tri-n-propylamine (TPrA) System: Crucial Role of the Long Lifetime of TPrA•+ Cation Radicals Suggested by Electrode Surface Effects
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DOI：
10.1021/jp802873e
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发表时间：
2008-10-01
影响因子：
3.7
通讯作者：
Zu, Yanbing
中科院分区：
文献类型：
--
作者：
Chen, Zuofeng;Zu, Yanbing
研究了电化学处理对Ru(Bpy)(3)(2+)(bpy=2，2‘-联吡啶)/三正丙胺(TPrA)体系电致化学发光的影响。研究发现，经阳极处理的GCEs上TPrA的氧化变得更加容易，而ECL的强度却被大大抑制。首次报道了电化学反应动力学与电致发光强度之间的矛盾，并将其归因于前处理过程中GCE上形成的含氧表面物种对TPrA(中心点+)阳离子自由基的快速去质子化。由于TPrA(中心点+)的寿命缩短，去质子化反应的产物TPrA(中心点)自由基更容易在电极上被氧化消耗，导致ECL信号变弱。然而，当ECL主要按照催化路线生产时，电极表面效应要小得多。这项研究表明，TPrA(中心点+)阳离子自由基的长寿命可能是产生强烈发光的关键，这使得足够数量的高度还原的中间自由基TPrA(中心点)在被电极破坏之前在相对较厚的反应层内参与ECL过程。
We describe the effects of electrochemical pretreatment of glassy carbon electrodes (GCEs) on the electrogenerated chemiluminescence (ECL) of the Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine)/tri-n-propylamine (TPrA) system. It has been found that the oxidation of TPrA at the anodically pretreated GCEs became more facile, while the intensity of ECL could be greatly suppressed. The contravention between the electrochemical reaction kinetics and the light emission intensity of the coreactant ECL system was reported for the first time and has been attributed to the rapid deprotonation of TPrA(center dot+) cation radicals by the aid of oxygen-containing surface species formed on the GCE during the pretreatment. Because the lifetime of TPrA(center dot+) was reduced, the products of the deprotonation reaction, TPrA(center dot) free radicals, would be more subject to oxidative consumption on the electrode subsequently, leading to weaker ECL signals. When the ECL was produced mainly following a catalytic route, however, the electrode surface effect was much less significant. This study suggests that the long lifetime of TPrA(center dot+) cation radicals may be crucial for the intense light emission, which allows a sufficient amount of highly reducing intermediate radicals, TPrA(center dot), to participate in the ECL process within a relatively thick reaction layer before being destroyed by the electrode.