Herrer I Lucia, Ismael Ali K, Milán David C, Vezzoli Andrea, Martín Santiago, González-Orive Alejandro, Grace Iain, Lambert Colin, Serrano José L, Nichols Richard J, Cea Pilar
Departamento de Química Física, Facultad de Ciencias , Universidad de Zaragoza , 50009 Zaragoza , Spain.
Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopias Avanzadas (LMA), edificio i+d Campus Río Ebro , Universidad de Zaragoza , C/Mariano Esquillor, s/n , 50018 Zaragoza , Spain.
J Phys Chem Lett. 2018 Sep 20;9(18):5364-5372. doi: 10.1021/acs.jpclett.8b02051. Epub 2018 Sep 5.
Electrical conductance across a molecular junction is strongly determined by the anchoring group of the molecule. Here we highlight the unusual behavior of 1,4-bis(1H-pyrazol-4-ylethynyl)benzene that exhibits unconventional junction current versus junction-stretching distance curves, which are peak-shaped and feature two conducting states of 2.3 × 10 G and 3.4 × 10 G. A combination of theory and experiments is used to understand the conductance of single-molecule junctions featuring this new anchoring group, i.e., pyrazolyl. These results demonstrate that the pyrazolyl moiety changes its protonation state and contact binding during junction evolution and that it also binds in either end-on or facial geometries with gold contacts. The pyrazolyl moiety holds general interest as a contacting group, because this linkage leads to a strong double anchoring of the molecule to the gold electrode, resulting in enhanced conductance values.
分子结的电导很大程度上由分子的锚定基团决定。在此，我们着重介绍1,4 - 双（1H - 吡唑 - 4 - 基乙炔基）苯的异常行为，它展现出非常规的结电流与结拉伸距离曲线，这些曲线呈峰形，具有2.3×10 G和3.4×10 G两种导电状态。运用理论与实验相结合的方法来理解具有这种新锚定基团（即吡唑基）的单分子结的电导。这些结果表明，吡唑基部分在结演化过程中会改变其质子化状态和接触结合方式，并且它还会以端接或面接的几何构型与金接触。吡唑基部分作为一种接触基团具有普遍的研究价值，因为这种连接方式会使分子与金电极形成强双锚定，从而提高电导值。
