Multicycle Desorption-Adsorption Voltammetry for Self-Assembled Mixed Monolayer Containing Ferrocenylthiol Molecules: A Discussion on Molecular Interaction in the Mixed Layer
Multicycle Desorption-Adsorption Voltammetry for Self-Assembled Mixed Monolayer Containing Ferrocenylthiol Molecules: A Discussion on Molecular Interaction in the Mixed Layer
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DOI：
10.5796/electrochemistry.75.523
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发表时间：
2007-07
期刊：
影响因子：
2.5
通讯作者：
Sho Fujii;K. Murase;H. Sugimura
中科院分区：
文献类型：
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作者：
Sho Fujii;K. Murase;H. Sugimura
采用交换法制备了由11-二茂铁基-1-十一烷乙氧基化物（11-FUT）和己基乙氧基化物（HT）分子组成的自组装混合单分子膜（mixed SAMs），并采用多电极电化学脱附-吸附伏安法对其进行了表征。伏安图的第一个循环显示出一个单一的解吸峰，尽管自组装膜具有由紧凑的11-FUT分子组成的域结构，表明一些残留的HT分子存在于11-FUT域中，并且在混合自组装膜中没有发生完全的相分离。然而，当混合自组装膜经历解吸-吸附循环时，其结构向温和的相分离结构转变，并且在第二循环的伏安图中发现两个独立的还原解吸峰，这清楚地证明所有混合自组装膜（在伏安分析之前），包括通过延长的交换反应制备的那些，确实含有11-FUT和HT分子。这证明了这种多峰伏安法对于混合自组装膜的重要性，混合自组装膜通常仅在第一次还原或负向扫描伏安图方面进行表征和讨论。即使在解吸-吸附循环之后，混合自组装膜中的二茂铁基也经历了Fe II/Fe III氧化还原，而氧化还原峰的强度变得减弱。
Self-assembled mixed monolayers (mixed SAMs) composed of 11-ferrocenyl-1-undecanethiol (11-FUT) and hexanethiol (HT) molecules were prepared through an exchange method and characterized by multicycle electrochemical desorption-adsorption voltammetry. The first cycles of the voltammograms showed a single desorption peak although the SAMs have a domain structure composed of compact 11-FUT molecules, indicating that some residual HT molecules were present in 11-FUT domains and that complete phase separation did not take place in the mixed SAMs. The structure, however, altered toward a mildly phase-separated structure when the mixed SAMs experienced desorption-adsorption cycle(s), and two separate reductive desorption peaks were found in the second cycles of voltammograms, which clearly evidenced that all mixed SAMs (before voltammetric analysis), including those prepared by prolonged exchange reactions, really contained both 11-FUT and HT molecules. This demonstrates the importance of such multicycle voltammetry for mixed SAMs that are usually characterized and discussed only in terms of the first reductive, or negative-going, scan of voltammograms. Even after the desorption-adsorption cycle(s), ferrocenyl groups in mixed SAMs underwent FeII/FeIII redox, while the intensity of redox peaks became weakened.