Discerning the Redox-Dependent Electronic and Interfacial Structures in Electroactive Self-Assembled Monolayers,Journal of the American Chemical Society

当前位置： X-MOL 学术 › J. Am. Chem. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Discerning the Redox-Dependent Electronic and Interfacial Structures in Electroactive Self-Assembled Monolayers
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-10-02 , DOI: 10.1021/jacs.8b05885
Raymond A. Wong ₁ , Yasuyuki Yokota ₁ , Mitsuru Wakisaka ₂ , Junji Inukai ₃ , Yousoo Kim ₁

Affiliation

We explore the redox-dependent electronic and structural changes of ferrocene-terminated self-assembled monolayers (Fc SAMs) immersed in aqueous solution. By exploiting X-ray and ultraviolet photoelectron spectroscopy combined with an electrochemical cell (EC-XPS/UPS), we can electrochemically control the Fc SAMs and spectroscopically probe the induced changes with the ferrocene/ferrocenium (Fc/Fc+) redox center (Fe oxidation state), formation of 1:1 Fc+-ClO4- ion pairs, molecular orientation, and monolayer thickness. We further find the insignificant involvement of interfacial water in the Fc SAMs irrespective of redox state. Electrolyte dependencies could be identified with 0.1 M NaClO4 and HClO4 when probing partially oxidized Fc/Fc+ SAMs. Corroborating the occurrence of electrochemically induced oxidation, EC-UPS shows that oxidation to Fc+ is accompanied by a shift of the highest occupied molecular orbital toward higher binding energy. The oxidation to Fc+ is also met with an increase in work function ascribed to the induced negative interfacial dipole caused by the presence of Fc+-ClO4- ion pairs along with a contribution from the reorientation of the Fc+ SAMs. The reversibility of our observations is confirmed upon conversion from Fc+ back to the neutral Fc. The approach shown here is beneficial for a broad range of redox-responsive systems to aid in the elucidation of structure-function relationships.

中文翻译：

识别电活性自组装单层中依赖于氧化还原的电子和界面结构

我们探索了浸入水溶液中的二茂铁封端的自组装单分子层 (Fc SAM) 的氧化还原依赖性电子和结构变化。通过利用 X 射线和紫外光电子能谱结合电化学电池 (EC-XPS/UPS)，我们可以电化学控制 Fc SAMs 并光谱探测二茂铁/二茂铁 (Fc/Fc+) 氧化还原中心（Fe 氧化）的诱导变化状态）、1:1 Fc+-ClO4- 离子对的形成、分子取向和单层厚度。我们进一步发现，无论氧化还原状态如何，界面水在 Fc SAM 中的参与都微不足道。在探测部分氧化的 Fc/Fc+ SAM 时，可以使用 0.1 M NaClO4 和 HClO4 确定电解质依赖性。证实电化学诱导氧化的发生，EC-UPS 表明，氧化为 Fc+ 伴随着最高占据分子轨道向更高结合能的转变。由于 Fc+-ClO4- 离子对的存在引起的诱导负界面偶极子以及 Fc+ SAM 重新定向的贡献，Fc+ 的氧化也会增加功函数。我们观察的可逆性在从 Fc+ 转换回中性 Fc 后得到证实。这里显示的方法有利于广泛的氧化还原响应系统，以帮助阐明结构 - 功能关系。由于 Fc+-ClO4- 离子对的存在引起的诱导负界面偶极子以及 Fc+ SAM 重新定向的贡献，Fc+ 的氧化也会增加功函数。我们观察的可逆性在从 Fc+ 转换回中性 Fc 后得到证实。这里显示的方法有利于广泛的氧化还原响应系统，以帮助阐明结构 - 功能关系。由于 Fc+-ClO4- 离子对的存在引起的诱导负界面偶极子以及 Fc+ SAM 重新定向的贡献，Fc+ 的氧化也会增加功函数。我们观察的可逆性在从 Fc+ 转换回中性 Fc 后得到证实。这里显示的方法有利于广泛的氧化还原响应系统，以帮助阐明结构 - 功能关系。

更新日期：2018-10-02

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南11