Understanding the Fundamental Behavior of Single Molecule Electrical Junctions

在这项由化学系化学结构、动力学和机理(CSDM-A)计划支持的项目中，坦普尔大学的Eric Borguet教授和他的学生试图了解目标分子的化学修饰如何影响分子内不同方向的电荷传输。运动电子是化学和生物学的核心。这一过程对电子通过的分子的电子性质以及嵌入分子的环境的化学和物理性质很敏感，因此可以控制。这是通过在纳米级的结中捕获单个分子来实现的，在那里测量电学性质。这些知识将被利用来实现所需的单分子结电子特性，并最终可能使分子开关和传感的有用设备平台的开发成为可能。虽然众所周知，化学取代改变了分子的电子性质，但对垂直于分子平面测量的电导与沿分子平面测量的电导的影响尚未确定。利用电化学环境中控制分子取向的能力(如直立或平直)，利用电化学环境中的电极电位，可以通过测量一系列具有不同官能团的分子的电导方向相关性来解决这个问题。计算表明，小的苯衍生物有希望以一种意想不到的方式调节电导率，例如，对不同的分子取向有不同的影响。对生成的大型复杂数据集的分析将通过复杂的工具实现，以识别低概率事件和多个可能的交叉点配置。就更广泛的科学影响而言，这些基础性研究有可能为纳米电子和传感器等新兴技术建立有效的系统。在教育更广泛的影响方面，高中生、本科生和研究生将有机会与最先进的测量、数据分析和理论方面的国际专家团队一起参与这项合作研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In this project supported by the Chemical Structure, Dynamics and Mechanisms-A (CSDM-A) Program of the Division of Chemistry, Professor Eric Borguet and his students at Temple University seek to understand how chemical modification of a target molecule affects charge transport along different directions inside the molecule. Moving electrons lie at the heart of chemistry and biology. This process is sensitive to, and therefore can be controlled by, the electronic properties of the molecules through which the electrons travel as well as the chemical and physical properties of the environment in which the molecules are embedded. This is done by trapping a single molecule in a nanoscale junction where the electrical properties are measured. This knowledge will be exploited to achieve desired single molecule junction electronic characteristics, and may ultimately enable the development of useful device platforms for molecular switching and sensing. While it is known that chemical substitution changes the electronic properties of molecules, the impact on the conductance measured perpendicular to the molecular plane vs. that measured along the molecular plane has not been determined. Taking advantage of the ability to control molecular orientation in a junction (e.g. upright or flat), using the electrode potential in an electrochemical environment, this question will be tackled by measuring the directional dependence of the conductance of a series of molecules with different functional groups. Calculations suggest promising chemical substitutions of small benzene derivatives that modulate electrical conductivity in an unanticipated manner, e.g., different effects for different molecular orientations. The analysis of the large complex data sets generated will be enabled by sophisticated tools to identify low probability events and multiple possible junction configurations. In terms of scientific broader impacts, these fundamental studies have the potential to enable the construction of efficient systems for nascent technologies, such as nanoscale electronics and sensors. In terms of educational broader impacts, high school, undergraduate and graduate students will have the opportunity to participate in this collaborative study with an international team of experts in state-of-the-art measurement, data analysis and theory.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.