Abstract We have explored the intermolecular interactions within a two-component self-assembled monolayer, a model system to develop our understanding of interfacial chemistry in molecular level. The redox signal of 11-ferrocenyl-1-undecanethiol (FcC11) reversibly responded to the formation of intermolecular H-bonding: The intermolecular H-bonding between the terminal carboxyl groups of MSA promoted the formation of MSA assemblies, which increased the influence of MSA on the neighboring molecules (FcC11). Meanwhile, the disordered FcC11 appeared within the locally ordered FcC11 patches, resulting in the presence of a new couple of redox peaks in the cyclic voltammograms. The surface coverage that corresponding to the H-bonding affected FcC11 increased exponentially from 0 to 3.49 × 10−10 mol cm−2 as a function of the time of MSA assembly. The pK1/2 value (the pH when half of the –COOH groups are ionized) that determined for the FcC11/MSA modified gold substrate was obviously higher than the alkanoic acids in aqueous solution. The results show that the intermolecular H-bonding between MSA molecules plays a key role in controlling the molecular assembly within the two-component self-assembled monolayer, which provides an approach for regulating the structural changes of the model membrane in molecular level.

中文翻译：

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分子间氢键对-COOH和二茂铁封端SAM酸碱界面性质的影响

摘要 我们探索了双组分自组装单层内的分子间相互作用，这是一个模型系统，可在分子水平上加深我们对界面化学的理解。11-ferrocenyl-1-undecanethiol (FcC11) 的氧化还原信号可逆地响应分子间氢键的形成：MSA 末端羧基之间的分子间氢键促进了 MSA 组装体的形成，从而增加了 MSA 的影响在相邻分子 (FcC11) 上。同时，无序的 FcC11 出现在局部有序的 FcC11 斑块中，导致循环伏安图中出现一对新的氧化还原峰。作为 MSA 组装时间的函数，对应于 H 键影响 FcC11 的表面覆盖率从 0 呈指数增加到 3.49 × 10-10 mol cm-2。FcC11/MSA 修饰的金底物测定的 pK1/2 值（一半-COOH 基团被电离时的 pH 值）明显高于水溶液中的链烷酸。结果表明，MSA分子之间的分子间氢键在控制双组分自组装单层内的分子组装中起关键作用，为在分子水平上调控模型膜的结构变化提供了途径。