Porphyrin single molecule wires for nanoelectronics

用于纳米电子学的卟啉单分子线

• 批准号: EP/D07665X/1
• 负责人: Richard Nichols
• 金额: $ 22.04万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD07665X%2F1
• 关键词: Porphyrin; single; molecule; wires; nanoelectronics

The prime aspiration of molecular nanoelectronics is to fabricate and interconnect molecules that can replace, or at least augment, present silicon based technology, with the molecules functioning as interconnects, switches, transistors or even logic gates. Clearly big challenges exist if such technologies are ever to reach fruition. In this respect, one of the key scientific challenges is to synthesise and reliably connect single molecular wires which can transport charge over long distance and also perform other functions such as rectifying current or storing charge. This proposal is aimed at synthesising extended molecular wires from a class of molecules called porphyrins, whose synthesis and functionalisation is the focus of the Oxford group. These electrical properties of these well-characterised molecules will be investigated at Cardiff and Liverpool, particularly their efficiency as molecular wires, their contacts with metal electrodes and their potential for electrochemical control in devices. The porphyrin wires to be synthesised are conjugated, stiff and contain sites where charge can be localised. Other key attributes include lengths greater than 10 nm, remarkable stability, their ability to bind a wide range of metal ions and their capacity to be tuned with electrochemistry or photochemistry. It is expected that their attributes will allow them to conduct electrons over long distances. Their redox activity and ability to support pendent molecular groups will in turn provide avenues for current rectification, switching or charge storage. The investigations of the electrical properties of these porphyrin wires will require us to wire-up single molecules. This is clearly a big experimental challenge but the Liverpool group has recently developed new techniques using the scanning tunnelling microscope which makes this procedure more straightforward and reliable. These techniques will provide robust chemical contact of the single porphyrin molecules at both ends to metallic contacts. The role of the molecule/metal contact remains one of the most poorly understood and yet extremely important aspects of single molecule electronics. We will systematically investigate these contact effects through the use of several differing chemical groups for binding to the metal electrodes and complementary determination of the lineup of energy levels between the metal and the molecule. Although most of the electrical characterisation will be performed with two metal contacts at either end of the wire, in the later stages of the project a scanning probe contact will be introduced which can be scanned along the length of the wire probing electrical properties along the wire. The final goals of the project are to produce a series of novel porphyrin molecular wires and to have defined and understood electron transport across them down to the single molecule level and in different environments including UHV and electrolyte. Being able to probe the key variables (temperature, environment, oxidation state, metal atom, molecule stiffness, contact chemistry) for one molecular system will provide a systematic approach for formulating detailed mechanisms. In particular, the limiting roles of contact chemistries and non-ideal charge transport (inelastic scattering) processes will be defined. The ideal porphyrin molecular wire would support high currents and we will assess how closely this goal (quantum conductance limit) can be approached. We will also have evaluated the ability of these molecules to act as active molecular wires through the placement of redox addressable groups along their length.

分子纳米电子学的主要愿望是制造和互连可以取代或至少增强现有硅基技术的分子，使分子充当互连、开关、晶体管甚至逻辑门。显然，如果此类技术要取得成果，就存在巨大的挑战。在这方面，关键的科学挑战之一是合成并可靠地连接单分子线，该线可以长距离传输电荷，并执行其他功能，例如整流电流或存储电荷。该提案旨在从一类称为卟啉的分子合成延伸的分子线，其合成和功能化是牛津小组的重点。卡迪夫和利物浦将研究这些经过充分表征的分子的电学特性，特别是它们作为分子线的效率、它们与金属电极的接触以及它们在设备中电化学控制的潜力。待合成的卟啉线是共轭的、坚硬的并且包含可以定位电荷的位点。其他关键属性包括长度大于 10 nm、卓越的稳定性、结合多种金属离子的能力以及通过电化学或光化学进行调节的能力。预计它们的属性将使它们能够长距离传导电子。它们的氧化还原活性和支持悬垂分子基团的能力反过来将为电流整流、开关或电荷存储提供途径。对这些卟啉线的电特性的研究将需要我们连接单个分子。这显然是一个巨大的实验挑战，但利物浦小组最近开发了使用扫描隧道显微镜的新技术，这使得该过程更加简单和可靠。这些技术将为两端的单个卟啉分子与金属接触提供牢固的化学接触。分子/金属接触的作用仍然是单分子电子学中最不为人所知但又极为重要的方面之一。我们将通过使用几种不同的化学基团与金属电极结合并互补确定金属和分子之间的能级排列来系统地研究这些接触效应。尽管大多数电气特性将通过导线两端的两个金属触点来执行，但在项目的后期阶段将引入扫描探针触点，该触点可以沿着导线的长度进行扫描，以探测沿着导线的电气特性。该项目的最终目标是生产一系列新型卟啉分子线，并定义和理解电子在它们之间的传输直至单分子水平以及在包括特高压和电解质在内的不同环境中的电子传输。能够探测一个分子系统的关键变量（温度、环境、氧化态、金属原子、分子刚度、接触化学）将为制定详细机制提供一种系统方法。特别是，将定义接触化学和非理想电荷传输（非弹性散射）过程的限制作用。理想的卟啉分子线将支持高电流，我们将评估可以在多大程度上实现这一目标（量子电导极限）。我们还将评估这些分子通过沿其长度放置氧化还原可寻址基团作为活性分子线的能力。

项目成果

Long-range electron tunnelling in oligo-porphyrin molecular wires.

寡卟啉分子线中的长程电子隧道。

• DOI: http://dx.10.1038/nnano.2011.111
• 发表时间: 2011
• 期刊: Nature nanotechnology
• 影响因子: 38.3
• 作者: Sedghi G

Oligoyne single molecule wires.

Oligoyne 单分子线。

• DOI: 10.1021/ja9061129
• 发表时间: 2009-11-04
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: Changsheng Wang;A. Batsanov;M. Bryce;S. Martín;R. Nichols;S. Higgins;V. García;C. Lambert
• 通讯作者: C. Lambert

Detecting Mechanochemical Atropisomerization within an STM Break Junction

检测 STM 断裂连接处的机械化学阻转异构化

• DOI: http://dx.10.1021/jacs.7b10542
• 发表时间: 2018
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: Leary E

Comparison of the conductance of three types of porphyrin-based molecular wires: ß,meso,ß-fused tapes, meso-Butadiyne-linked and twisted meso-meso linked oligomers.

三种卟啉基分子线的电导率比较：α、内消旋、β-熔合带、内消旋-丁二炔连接和扭曲的内消旋-内消旋连接低聚物。

• DOI: http://dx.10.1002/adma.201103109
• 发表时间: 2012
• 期刊: Advanced materials (Deerfield Beach, Fla.)
• 作者: Sedghi G

Ionic Liquids As a Medium for STM-Based Single Molecule Conductance Determination: An Exploration Employing Alkanedithiols

离子液体作为基于 STM 的单分子电导测定的介质：使用链烷二硫醇的探索

• DOI: 10.1021/jp206241d
• 发表时间: 2011-09-25
• 期刊: Journal of Physical Chemistry C
• 影响因子: 3.7
• 作者: Nicola J. Kay;R. Nichols;S. Higgins;W. Haiss;Gita Sedghi;W. Schwarzacher;B. Mao
• 通讯作者: B. Mao