Understanding the Fundamental Behavior of Single Molecule Electrical Junctions

在天普大学化学系化学结构、动力学和机理a （CSDM-A）项目的支持下，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沿不同方向的电荷传输。移动的电子是化学和生物学的核心。这一过程对电子所经过的分子的电子特性以及分子所处环境的化学和物理特性很敏感，因此可以通过这些特性来控制。这是通过将单个分子捕获在纳米级连接处来实现的，在连接处测量其电学特性。这些知识将被用来实现所需的单分子结电子特性，并可能最终使分子开关和传感的有用设备平台的发展成为可能。虽然我们知道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和沿着分子平面测量的电导的影响还没有确定。利用电化学环境中电极电位控制结中的分子取向（例如直立或平坦）的能力，这个问题将通过测量一系列具有不同官能团的分子的电导的方向依赖性来解决。计算表明，小苯衍生物有希望以意想不到的方式调节电导率，例如，不同分子取向的不同效果。对生成的大型复杂数据集的分析将通过复杂的工具来识别低概率事件和多种可能的结配置。就更广泛的科学影响而言，这些基础研究有可能为新兴技术（如纳米级电子学和传感器）构建有效的系统。就更广泛的教育影响而言，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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.