偶氮苯衍生物-β-环糊精包合物的自组装行为

研究了4-N（2’-巯基-乙基）羧基酰胺偶氮苯（Azo）与β-环糊精（β-CD）形成的包合物在金表面上的自组装行为．X射线光电子能谱（XPS）结果证实，Azo和Azo与β-CD形成的包合物均可在金表面上自组装形成单分子层膜．在包合物形成的自组装膜中，Azo与β-CD的摩尔比约为1：1．Azo自组装膜的电化学反应表现速率常数（Kobs）随组装时间的延长而明显减小，反映出自组装膜的排列随时间延长而趋于更加致密，从而抑制了偶氮苯基团的电化学诱导构型转化，降低了其电活性．而Azo与β-CD包合物自组装膜的Kobs值随组装时间变化不大，在组装76h以后，包合物自组装膜的Kobs比单纯偶氮苯自组装膜的Kobs高2个数量级以上．表明环糊精能够将偶氮苯分子隔开，从而抑制了偶氮苯在自组装膜中的聚集作用，有效地提高其电化学活性．

Self-assembly Behavior of Azobenzene Derivative β-Cyclodextrin Inclusion Complex on Gold

The self assembly behavior of inclusion complex of 4- N (2' -meraptoethyl) carboxylamino-azobenzene (Azo) with β-cyclodextrin (β-CD) on gold surface have been studied. X-ray photoelectron spectroscopy (XPS ) results suggested that the monlayers of Azo β-CD inclusion complex was formed on gold surface by self-assembly. The molar ratio of azobenzene and β-CD on gold surface was estimated to be 1: 1 by XPS. The apparent electrochemical rate constant (Kobs) of Azo SAM decreases with increasing assembling time that is attributed to increasing packing-density of Azo in the monolayer. The close packed structures in Azo SAM restrict the conformation change of azobenzene units in the film so tha it leads to a decrease of its electrochemical activity. In contras, the Kobs of complex SAM changes slightly with the assembling time. After an assembling time of 76 h, the Kobs of complex SAM is two order of magnitude larger than that of Azo SAM. The higher electrochemical activity of azobenzene groups in the complex SAM than that in Azo SAM suggests that the Azo moieties are separated by β-CD in the complex SAM.