Real time tracking of the propagation of phase-transition front induced by potential control for organic thin films on electrode surfaces

电极表面有机薄膜电位控制诱导相变前沿传播的实时跟踪

• 批准号: 14550794
• 负责人: SAGARA Takamasa
• 金额: $ 2.3万
• 依托单位: Nagasaki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550794/
• 关键词: Electrode surface; Organic monolayer; Phase transition; Surface Propagation; Viologen; Dendrimer; Amphiphiles; Molecular Assembling Structure

The 2-dimensional (2D) phase transition of viologens was investigated. In the case of heptyl viologen (HV), the first-order phase transition between gas-like adsorption layer of oxidized form and 2D condensed phase of reduced form produces a spike-like voltammetric response. Measurements of UV visible light reflectance transitions in response to double potential step enabled us to establish 1:1 coexistence of the two phases even within the bi-stable potential region of the first order transition. It was found that the width of the bi-stable potential region can be regulated by intermolecular interaction in the condensed film. We newly made it possible to track the phase transition front using the interfacial potential difference measurements with a row of micro-probe electrodes, though the potential change was too small to catch the movement of the front. We also **ed to see the front using a fluorescence microscope and the local reflection measurements, but it was difficult to see the … More front.The phase change of amphiphilic molecules with terminal adsorption-desorption active groups, such as 4-pyridyl or imidazo-1-yl, was investigated at a Au(111) single crystal electrode. All these molecules showed dynamic phase changes ranging from compact monolayer to desorbed aggregated structure. The changes are sensitive to the molecular structures. The effects of the existence of the amide linkage, position of the linkage, pH, the presence of bicarbonate ion, and number of the touching procedures upon the phase change were explored. The potential dependent phase change was clearly tracked using the spectroelectrochemical techniques.The pontential-induced reversible phase change of the adsorption layer of a dendrimer was realized for the first time. A PAMAM dendrimer, the periphery of which, was totally modified with 4-pyridyl groups, exhibited reversible partial desorption-readsorption behavior as well as orientational change of peripheral groups on a Au(111) electrode surface in an unbuffered KClO_4 aqueous solution. Less

研究了紫罗碱的二维相变。在庚基紫精（HV）的情况下，氧化形式的气体状吸附层和还原形式的二维凝聚相之间的一级相变产生尖峰状伏安响应。通过对双电位阶跃引起的紫外-可见光反射率跃迁的测量，我们证实了即使在一级跃迁的双稳电位区，两个相也能1：1共存。结果表明，双稳势区的宽度可以通过凝聚膜中分子间的相互作用来调节。我们新提出了一种用一排微探针电极测量界面电位差来跟踪相变前沿的方法，尽管电位变化太小而不能捕捉到前沿的运动。我们艾德用荧光显微镜和局部反射测量来观察前面，但很难看到前面。 ...更多信息 研究了带有末端吸附-脱附活性基团（如4-吡啶基或咪唑-1-基）的两亲分子在Au（111）单晶电极上的相变。所有这些分子都表现出从致密的单层到脱附聚集结构的动态相变。这些变化对分子结构很敏感。探讨了酰胺键的存在、键的位置、pH值、碳酸氢根离子的存在以及接触次数对相变的影响。利用光谱电化学技术对电位相关相变进行了清晰的跟踪，首次实现了树枝状大分子吸附层的电位诱导可逆相变。在KClO_4水溶液中，PAMAM树枝状大分子在Au（111）电极表面上表现出可逆的部分脱附-再吸附行为，同时其周围基团的取向也发生了变化。少

项目成果

Takamasa Sagara: "Dynamic Dendrimer at Electrified Interface : Potential Dependent Adsorption-Desorption and Reorientation of a 4-Pyridyl-Modified PAMAM Dendrimer"Chemical Communications. 2002・8. 2116-2117 (2002)

Takamasa Sagara：“带电界面的动态树枝状聚合物：4-吡啶基修饰的 PAMAM 树枝状聚合物的电位依赖性吸附-解吸和重新取向”化学通讯 2002・8（2002 年）。

Takamasa Sagara: "Dynamic Dendrimer at Electrified Interface : Potential Dependent Adsorption-Desorption and Reorientation of a 4-Pvridvl-Modified PAMAM Dendrimer"Chemical Communications. 2002. 2116-2117 (2002)

Takamasa Sagara：“带电界面的动态树枝状聚合物：4-Pvridvl 修饰的 PAMAM 树枝状聚合物的电位依赖性吸附-解吸和重新取向”化学通讯。

Takamasa Sagara, Kumi Nagata, Hiroaki Tsuruta, Naotoshi Nakashima: "Dynamic Dendrimer at Electrified Interface : Potential Dependent Adsorption-Desorption and Reorientation of a 4-Pyridyl-Modified PAMAM Dendrime"Chemical Communications. 18. 2116-2117 (200

Takamasa Sagara、Kumi Nagata、Hiroaki Tsuruta、Naotoshi Nakashima：“带电界面的动态树枝状聚合物：4-吡啶基改性 PAMAM 树枝状聚合物的电位依赖性吸附-解吸和重新取向”化学通讯。

Takamasa Sagara: "Characteristics of faradaic phase transition of an adsorption layer of heptyl viologen at a basal plane HOPG electrode"Journal of Electroanalytical Chemistry. 524-525・0. 68-76 (2002)

Takamasa Sagara：“基面HOPG电极上庚基紫精吸附层的法拉第相变特性”电分析化学杂志524-525・0（2002年）。

Takamasa Sagara: "Double potential step chrono-reflectometory approach to bi-stable potential region of the faradaic phase transition of heptyl viologen at a HOPG electrode"Journal of Electroanalytical Chemistry. 未定. (2004)

Takamasa Sagara：“HOPG 电极上庚基紫精法拉第相变双稳态电位区域的双电位步长反射测量法”电分析化学杂志（2004 年）。