不同亲水性探针分子在金电极上硫醇自组装跨膜动力学研究  

Studies on Kinetics of Different Types of Probing Species Through Self-assembled Monolayers on a Gold Electrode by SECM

作　　者：陈忠[1] 沈丽[1] 谢书宝[1] 何莎莉[1] 静平[1] 徐晓东[1] 邵元华[1] 

机构地区：[1]北京分子科学国家实验室,北京大学化学与分子工程学院分析化学研究所,北京100871

出　　处：《高等学校化学学报》2008年第4期700-704,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20735001,20628506和20475003);博士学科点基金;北京大学“985”子项目基金资助

摘　　要：采用扫描电化学显微镜测定了不同亲水性氧化还原电对在硫醇修饰的金电极表面上的异相电子转移速率常数.分别选择铁氰化钾[K3Fe(CN)6]和N,N,N′,N′-四甲基-1,4苯二胺(TMPD)作为氧化还原探针,根据得到的反馈曲线拟合出异相电子转移速率常数.比较这些速率常数可以看出,修饰层对疏水性的TMPD分子显示出更好的穿透性.通过一个简单的模型可以解释TMPD的穿透过程,在TMPD电子隧穿的前后存在着单层膜和水溶液间的快速平衡,而隧穿作为决速步骤,其表观速率常数也比K3Fe(CN)6的大.通过计算得到TMPD的隧穿因子β为1.2/CH.In this paper, the kinetic behavior of mediators with different polarities at n-alkanethiol modified gold electrode are investigated by scanning electrochemical microscopy（SECM）. Ferrocyanide [ K4Fe（CN） 6 ] and N,N,N′,N′-tetramethyl-p-phenylenediamine（TMPD） are employed as the mediators, and the serf-assembled monolayers（SAMs） act as a better blocking barrier for the transport of ferrocyanide than that of TMPD. This difference is mainly because of the better permeation of TMPD into the hydrophobic monolayers. A simple model is applied to extract the kinetic rate constants of the permeation step. On the basis of the kinetic rate constants obtained, we can deduce that the equilibriums exist before and after the electronic transfer （ET） when using TMPD, and the apparent kinetic constant is larger than ferrocyanide in this step. The tunneling decay constant of the TMPD in the SAMs, β, can be measured to be equal to 1.2 per methylene group.

关 键 词：自组装单层 跨膜转移动力学 扫描电化学显微镜 N N N′ N′-四甲基-1 4苯二胺 

分 类 号：O646[理学—物理化学]