生物醌分子伏安响应的多电子转移辨析  

Resolve Mono-Electronic Process in the Voltammetric Behaviors of Multi-Redox Bis-Coenzyme Q_0

作　　者：周浩[1] 龙亿涛[1] 

机构地区：[1]华东理工大学结构可控先进功能材料及其制备教育部重点实验室,上海200237

出　　处：《电化学》2014年第6期533-537,共5页Journal of Electrochemistry

基　　金：国家杰出青年基金(No.21125522);上海高校特聘教授(东方学者;跟踪计划)资助

摘　　要：电化学反应中,一个基元电子转移反应仅对应一个电子交换,实际上多电子转移反应也涉及对应数目的单电子转移步骤,分离、辨析每个电子基元反应的氧化还原峰电位十分重要.本文以辅酶Q0(Co Q0)、亚甲基桥连双辅酶Q0(Bis-Co Q0)为模型,采用循环伏安和方波伏安技术研究其电化学特性,提出了一种应用于多电子转移体系、分析单个电子转移电位的方法.实验表明,Co Q0经历两步单电子还原反应.Bis-Co Q0中两个醌单元发生强电子相互作用,电极过程为4电子多步转移.对于表观上的4电子"三步"转移反应,拟用Lorentzian-Gaussian分峰拟合Co Q0和Bis-Co Q0体系方波伏安响应曲线,分别获取每个电子转移步骤的电位,进一步证明Bis-Co Q0经历四分步单电子转移反应,为热力学研究提供更多信息.A widely held concept in electrochemistry is that truly elementary electron-transfer reactions always involve the exchange of one electron, therefore, an overall process involving a change of n electrons must involve n distinct electron-transfer steps. It is highly desirable to resolve multiple-step electron transfer reactions into each electron transfer step. The electrochemical behaviors of coenzyme Qo and methylene-bridged bis-coenzyme Q0 were investigated by cyclic voltammetry and square wave voltammetry in nonaqueous dichloromethane containing 0.15 mol· L^-1 Bu4NClO4 as the supporting electrolyte. The redox reaction of coenzyme Q0 is well described as two chemically reversible one-electron reduction processes. Bis-coenzyme Q0 exhibits three redox waves in voltammetric experiment, as two bridged coenzyme Q0 units show strong intramolecular electron communication. Experimental data were curve fitted with a Gaussian and Lorentzian mixed product function after subtracting the Shirley background. Results show that four-electron reduction of his-coenzyme Q0 is preceded by stepwise pathways, defining as four successive, mono-electronic electron-transfer steps.

关 键 词：辅酶Q0 电子相互作用 方波伏安法 多电子转移 分峰 单电子响应辨析 

分 类 号：O646[理学—物理化学]