自组装膜结构与电化学行为的关系

Structure-Dependent Electron Transfer Kinetics of Azobenzene Self-Assembled Monolayers on Gold

报导了组装时间对4-乙氧基-4'-N（2”-巯基-乙基）羧基酰胺-偶氮苯（C2AzoC2）自组装膜电化学行为的影响，接触角与界面电容的数据表明；组装时间的增长使自组装膜表面覆盖度增加．从循环伏安图中可以观察到氧化峰与还原峰之间的距离增大，同时计算得到的表观电极反应速率常数显著减小.基于偶氮苯基团的自身结构及其在电化学反应过程中所经历的构型改变，认为有序体系中组装结构的致密性阻碍偶氮苯基团的构型变化，使成膜分子氧化还原过程的活化能升高，从而导致了表观电子转移速率常数的减小．

The self-assembling process and electrochemical behavior of (4-ethoxy-4'-N-(2'-mercaptoethyl) aminocarbonyl-azobenzene monolayer on gold were investigated by cyclic voltammetry and contact angle measurements. The apparent electron transter rate constant Ks was found to decrease with increasing the surface coverage. Taking account of the structural change associated with the reduction/oxidation process of azobenzene to hydrazobenzene, the unique decrease of apparent electron-transter rate constants could be well understood by the inhibition on such a molecular structure change of close packing film structure, which may lead to an increase of activation free energy for the reduction/oxidation process.