Ion-Pair Formation between Ferrocene-Terminated Self-Assembled Monolayers and Counteranions Studied by Force Measurements
Ion-Pair Formation between Ferrocene-Terminated Self-Assembled Monolayers and Counteranions Studied by Force Measurements
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DOI：
10.1021/jp2001404
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发表时间：
2011-03
影响因子：
3.7
通讯作者：
Y. Yokota;Taro Yamada;M. Kawai
中科院分区：
文献类型：
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作者：
Y. Yokota;Taro Yamada;M. Kawai
在0.05 M HClO4溶液中，在尖端电位和样品电位独立控制下，利用原子力显微镜研究了氧化二茂铁端部自组装单层膜（SAMs）和反阴离子之间离子对的形成。系统的稳定性由缩回力曲线表征，其中尖端和样品之间的附着力都被SAMs覆盖，可以通过调节外加电位作为二茂铁部分氧化态的函数来可逆地调节。与带正电的氨基端SAMs相比，在两个氧化端二茂铁SAMs的接近曲线上没有观察到与未补偿的反阴离子相对应的剩余表面电荷的净排斥力。当电解质溶液的浓度降低到0.005 M时，观察净排斥力。我们发现氧化二茂铁基团和电解质阴离子的离子对层具有净表面。
The formation of ion pairs between oxidized ferrocene-terminated self-assembled monolayers (SAMs) and counteranions was investigated using atomic force microscopy under independent controls of the tip and sample potentials in a 0.05 M HClO4 solution. The stability of the system was characterized by retraction force curves, where the adhesion force between the tip and the sample both covered by SAMs can be reversibly tuned by adjusting the applied potentials as a function of the oxidation states of ferrocene moieties. The net repulsive force, which corresponds to a residual surface charge uncompensated with the counteranions, was not observed on the approach curves between two oxidized ferrocene-terminated SAMs, in contrast to the case of positively charged amino-terminated SAMs. When the concentration of the electrolyte solution was decreased to 0.005 M, the net repulsive force was observed. We revealed that the ion-pair layer of oxidized ferrocene moieties and the electrolyte anions possesses net surface...