Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States.
J Am Chem Soc. 2014 Jun 25;136(25):8867-70. doi: 10.1021/ja5034606. Epub 2014 Jun 16.
We report a novel strategy for the regulation of charge transport through single molecule junctions via the combination of external stimuli of electrode potential, internal modulation of molecular structures, and optimization of anchoring groups. We have designed redox-active benzodifuran (BDF) compounds as functional electronic units to fabricate metal-molecule-metal (m-M-m) junction devices by scanning tunneling microscopy (STM) and mechanically controllable break junctions (MCBJ). The conductance of thiol-terminated BDF can be tuned by changing the electrode potentials showing clearly an off/on/off single molecule redox switching effect. To optimize the response, a BDF molecule tailored with carbodithioate (-CS2(-)) anchoring groups was synthesized. Our studies show that replacement of thiol by carbodithioate not only enhances the junction conductance but also substantially improves the switching effect by enhancing the on/off ratio from 2.5 to 8.
我们报告了一种通过组合电极电势的外部刺激、分子结构的内部调节和锚定基团的优化来调节通过单分子结的电荷输运的新策略。我们设计了氧化还原活性苯并二呋喃（BDF）化合物作为功能电子单元，通过扫描隧道显微镜（STM）和机械可控的断裂结（MCBJ）来制造金属-分子-金属（m-M-m）结器件。通过改变电极电势可以调节巯基封端的BDF 的电导率，显示出明显的单分子氧化还原开关效应的关/开/关。为了优化响应，合成了带有碳二硫代（-CS2(-)）锚定基团的 BDF 分子。我们的研究表明，用碳二硫代代替巯基不仅增强了结的电导率，而且通过将开/关比从 2.5 提高到 8，大大提高了开关效应。
