Huang Bing, Liu Xu, Yuan Ying, Hong Ze-Wen, Zheng Ju-Fang, Pei Lin-Qi, Shao Yong, Li Jian-Feng, Zhou Xiao-Shun, Chen Jing-Zhe, Jin Shan, Mao Bing-Wei
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University , Jinhua 321004 , China.
Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , Wuhan 430079 , China.
J Am Chem Soc. 2018 Dec 19;140(50):17685-17690. doi: 10.1021/jacs.8b10450. Epub 2018 Dec 10.
The ability to control over the quantum interference (QI) effect in single molecular junctions is attractive in the application of molecular electronics. Herein we report that the QI effect of meta-benzene based molecule with dihydrobenzo[ b]thiophene as the anchoring group ( meta-BT) can be controlled by manipulating the electrode potential of the junctions in electrolyte while the redox state of the molecule does not change. More than 2 orders of magnitude conductance change is observed for meta-BT ranging from <10 to 10 G with varying the electrode potential, while the upper value is even larger than the conductance of para-BT ( para-benzene based molecule with anchoring group of dihydrobenzo[ b]thiophene). This phenomenon is attributed to the shifting of energy level alignment between the molecule and electrodes under electrode potential control. Calculation is carried out to predict the transmission function of single molecular junction and the work function of Au surface in the presence of the molecule, and good agreement is found between theory and experiments, both showing sharp-valley featured destructive QI effect for the meta-BT. The present work demonstrates that the QI effect can be tuned through electrochemical gating without change of molecular redox states, which provides a feasible way toward realization of effective molecular switches.
在单分子结中控制量子干涉（QI）效应的能力在分子电子学应用中具有吸引力。在此我们报道，以二氢苯并[b]噻吩为锚定基团的间苯撑基分子（间苯撑-BT）的QI效应可通过在电解质中操纵结的电极电位来控制，而分子的氧化还原状态不变。随着电极电位的变化，间苯撑-BT的电导变化超过2个数量级，范围从<10到10 G，而其上限甚至大于对苯撑-BT（以二氢苯并[b]噻吩为锚定基团的对苯撑基分子）的电导。这种现象归因于在电极电位控制下分子与电极之间能级排列的变化。进行了计算以预测单分子结的传输函数以及存在该分子时金表面的功函数，理论与实验结果吻合良好，均表明间苯撑-BT具有尖峰-谷特征的破坏性QI效应。本工作表明，QI效应可通过电化学门控进行调节而无需改变分子的氧化还原状态，这为实现有效的分子开关提供了一条可行途径。
