偶氮苯自组装单分子膜中长程电子转移机理

利用自组装技术在金电极表面构造了具有不同前端健长度偶氮苯功能化的单分子膜体系：Au／S（CH2）nNHCO-N＝N-OCH2CH3（n＝2，3，4，6）．研究结果表明，仍氮苯到金电极的表现电子转移速率随它们之间的距离长度的增加而呈指数性的下降趋势．基于Marcus电子隧穿理论，得到了此自组装膜体系的长程电子隧穿系数ρ＝（1．35±0．2）／CH2在和可逆电活性分子自组装膜体系及理论计算相比较的基础上，从偶氮苯分子自组装膜结构与电子转移过程的关系角度对这一结果进行了分析和说明．

Stuty of the Tunneling Mechanism for Long Range Electron Transfer in Azobenzene Self-assembled Monolayers

The tunneling mechanism for long range electron transfer in azobenzene self-assembled mololayers on gold has been studied by electrochemical techniques. We have prepared for the first time a series of azobenzene-tethered alkanethiol monolayers on gold electrode surface with varied number of methylenes in the alkyl chain spacer (CH3CH2-4-?-N=N-?-C(O)NH (CH2)nSH/Au, n=2, 3, 4, 6). The apparent electron transfer rate constants kapp of azobenzcne to the underlying electrode are found to fall off exponentially with increasing the length of alkyl chain spacers. Theelectron tunneling constant βfor the electron transfer in the present system are estimated to be 1.35±0.20 per CH2 from the logarithmic kapp. versus n (number of methylenes in the alkyl chain spacer) plot.