Electroactive Self-Assembled Monolayers: Putting Surface-Confined Redox Reactions to Work

拟议的研究旨在利用氧化还原终止的单分子膜以可能促进宏观到纳米尺度电化学技术发展的方式在固液界面电化学活化，驱动和调节物理化学过程。自组装单分子层（SAM）的有机硫醇，功能化与二茂铁，biferrocenylene，电子供体或电子受体部分，化学吸附到金表面被用作电活性分子界面。这些氧化还原活性自组装膜中的电荷转移诱导的变化将被用于微机械致动和二维系综的形成，包括固体支撑的脂质膜、溶致液晶纳米材料膜和纳米颗粒阵列。前者的研究目标是建立如何小（埃尺度）的构象变化可以电化学触发和利用执行更大规模的机械工作，而后者的目的是演示如何界面离子对或电荷转移复合物产生的氧化还原刺激可以用来创建表面吸附的组件。我们特别寻求建立的氧化还原部分的空间拥挤所发挥的作用，在单层骨架中的重复单元的数量，（超）在单层中的分子组织，分子间的货车德瓦尔斯相互作用，和离子对或电荷转移相互作用的强度的过程中调查。电荷存储在二元自组装膜，包括两个二茂铁衍生物与非重叠的氧化还原电位，以及biferrocenylene-terminated自组装膜，其氧化还原稳定性是远远上级通常的二茂铁终止的对应物，将研究电化学稳健的多态分子开关的发展。最后，局部表面等离子体激元激发对法拉第电化学和表面束缚分子的化学不稳定性的影响将被探索，其目的是促进表面限制的电化学反应，并使纳米结构的区域特异性化学功能化。预期的成果是开发氧化还原和光介导的过程，用于操纵固液界面的分子事件，并可用于工程功能氧化还原响应系统，如机电致动器，电子存储器或电光器件。

The proposed research is aimed at harnessing redox-terminated monomolecular films to electrochemically activate, drive, and modulate physicochemical processes at solid-liquid interfaces in ways that can potentially facilitate the development of macro- to nano-scale electrochemical technologies. Self-assembled monolayers (SAMs) of organothiolates, functionalized with ferrocene, biferrocenylene, electron donor or electron acceptor moieties, chemisorbed to gold surfaces are used as electroactive molecular interfaces. Charge-transfer-induced changes in these redox-active SAMs will be exploited for micromechanical actuation and the formation of two-dimensional ensembles, including solid-supported lipid membranes, films of lyotropic liquid crystal nanomaterials, and nanoparticle arrays. The objective of the former research thrust is to establish how small (angstrom-scale) conformational changes can be electrochemically triggered and harnessed to perform much larger-scale mechanical work, while that of the latter is to demonstrate how the interfacial ion pairs or charge transfer complexes generated by a redox stimulus can be used to create surface-adsorbed assemblies. We specifically seek to establish the roles played by the steric crowding of the redox moieties, number of repeat units in the monolayer backbone, (supra-)molecular organization in the monolayer, intermolecular van der Waals interactions, and the strength of the ion pair or charge transfer interactions on the processes investigated. Charge storage in binary SAMs comprising two ferrocene derivatives with nonoverlapping redox potentials, as well as biferrocenylene-terminated SAMs, whose redox stability is far superior to that of the usual ferrocene-terminated counterparts, will be investigated for the development of electrochemically robust multistate molecular switches. Finally, the effect of localized surface plasmon excitation on the Faradaic electrochemistry and chemical lability of surface-tethered molecules will be explored with the aim of facilitating surface-confined electrochemical reactions and enabling the regiospecific chemical functionalization of nanostructures. The expected outcomes are the development of redox- and light-mediated processes for manipulating molecular events at solid-liquid interfaces and that can be used to engineer functional redox-responsive systems such as electromechanical actuators, electronic memories or electrooptical devices.