Probing Hopping Conduction in Long, Pi-Conjugated Molecular Wires Assembled by Click Chemistry

探测通过点击化学组装的长π共轭分子线中的跳跃传导

• 批准号: 1213876
• 负责人: Daniel Frisbie
• 金额: $ 42万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213876&HistoricalAwards=false
• 关键词: Probing; Hopping; Conduction; Long; Pi

In this award sponsored by the Macromolecular, Supramolecular and Nanochemistry Program of the NSF, Prof. Dan Frisbie of the University of Minnesota and his students aim to understand how pai-conjugated molecules conduct electricity. In particular, their goal is to connect pi-conjugated molecules between metal electrodes and to probe conduction in the "hopping regime" in which electrons are injected into the molecular orbitals and hop from site-to-site along the molecular backbone, driven by the potential difference between the metal contacts. Building and characterizing the conduction of these structures will allow a better understanding of how molecular architecture impacts electrical conductivity in molecules. It will also allow useful electronic functions (e.g. current rectification) to be built into the molecular wires, which may enable new nanoelectronic applications. The experimental approach involves building pi-conjugated molecular wires from metal electrodes using sequential "click chemistry" reactions to connect monomers in a step-wise fashion. This chemistry allows the syntheses of molecular wires that are tens of nanometers in length with simultaneous control of the wire architecture on 1 nanometer length scales. Wires will be made with many different chemical functionalities, including redox-active sites, and with cascades of energy levels that can facilitate uni-directional electron transport (i.e., current rectification). After synthesis, the metal electrodes bearing oriented assemblies of wires will be inserted into an atomic force microscope (AFM), where the microscope probe tip will be brought into contact with the wire assembly with a controlled, nano-newton compressive load. In this manner, the AFM functions as an electrical probe station. Voltages applied between the metal AFM tip and the metal substrate drive current through the wires and the current-voltage (I-V) characteristics of the wires will be measured. The I-V characteristics will be recorded as a function of molecular length, chemical functionality and temperature. Analysis of this information will be used to create a more complete understanding of structure-conduction relationships in conducting molecules.The broader impacts of this proposal will be in the training of graduate students and undergraduates in important emerging areas of chemistry and nanoscience. In particular students will develop skills in molecular synthesis, structure characterization, atomic force microscopy, and electrical measurements. They will also develop a more complete physical understanding of the physical principles involved in electrical conduction in molecules and nanoelectronics, more generally. In addition, this grant will offer summer research opportunities for three high school students from the Twin Cities metropolitan area, exposing them to scientific research at an early stage and positively impacting their understanding of chemical concepts.

在这个由NSF的大分子，超分子和纳米化学计划赞助的奖项中，明尼苏达大学的Dan Frisbie教授和他的学生旨在了解pai共轭分子如何导电。特别是，他们的目标是连接金属电极之间的π共轭分子，并探测“跳跃状态”中的传导，其中电子被注入分子轨道并沿着分子骨架从一个位置跳到另一个位置，这是由金属触点之间的电势差驱动的。构建和表征这些结构的导电性将有助于更好地理解分子结构如何影响分子的导电性。它还将允许有用的电子功能（例如电流整流）被构建到分子线中，这可能使新的纳米电子应用成为可能。实验方法涉及使用顺序的“点击化学”反应从金属电极构建π共轭分子线，以逐步的方式连接单体。这种化学允许合成几十纳米长的分子线，同时控制1纳米长度尺度上的线结构。导线将被制成具有许多不同的化学功能，包括氧化还原活性位点，并且具有可以促进单向电子传输的能级级联（即，电流整流）。 在合成之后，将承载取向的线组件的金属电极插入到原子力显微镜（AFM）中，其中将使显微镜探针尖端与具有受控的纳牛顿压缩载荷的线组件接触。 以这种方式，AFM用作电探针台。施加在金属AFM针尖和金属衬底之间的电压驱动电流通过导线，并且将测量导线的电流-电压（I-V）特性。I-V特性将被记录为分子长度、化学官能度和温度的函数。对这些信息的分析将被用来更全面地理解导电分子的结构-导电关系，这一提议的更广泛影响将是对化学和纳米科学重要新兴领域的研究生和本科生的培训。特别是学生将发展在分子合成，结构表征，原子力显微镜和电气测量的技能。他们还将开发一个更完整的物理理解的物理原理涉及分子和纳米电子学中的导电，更普遍。此外，这笔赠款将为来自双城大都市区的三名高中生提供夏季研究机会，使他们在早期阶段接触科学研究，并积极影响他们对化学概念的理解。