Department of Chemistry, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Am Chem Soc. 2015 Jan 21;137(2):734-41. doi: 10.1021/ja509470w. Epub 2015 Jan 6.
Dendritic bis(terpyridine)iron(II) wires with terminal ferrocene units were synthesized on a Au(111) surface by stepwise coordination using a three-way terpyridine ligand, a ferrocene-modified terpyridine ligand, and Fe(II) ions. Potential-step chronoamperometry, which applied overpotentials to induce the redox of the terminal ferrocene, revealed an unusual electron-transport phenomenon. The current-time profile did not follow an exponential decay that is common for linear molecular wire systems. The nonexponentiality was more prominent in the forward electron-transport direction (from the terminal ferrocene to the gold electrode, oxidation) than in the reverse direction (from the gold electrode to the terminal ferrocenium, reduction). A plateau and a steep fall were observed in the former. We propose a simple electron transport mechanism based on intrawire electron hopping between two adjacent redox-active sites, and the numerical simulation thereof reproduced the series of "asymmetric" potential-step chronoamperometry results for both linear and branched bis(terpyridine)iron(II) wires.
具有末端二茂铁单元的树枝状双（三联吡啶）铁（II）线在 Au(111) 表面上通过分步配位合成，使用三向三联吡啶配体、二茂铁修饰的三联吡啶配体和 Fe(II)离子。应用过电位诱导末端二茂铁氧化还原的电位阶跃计时安培法揭示了一种不寻常的电子输运现象。电流-时间曲线没有遵循常见的线性分子线系统的指数衰减。在正向电子输运方向（从末端二茂铁到金电极，氧化）比在反向（从金电极到末端二茂铁正离子，还原）更为明显。前者观察到一个平台和一个陡峭的下降。我们提出了一种基于相邻两个氧化还原活性位点之间的线内电子跳跃的简单电子输运机制，其数值模拟再现了线性和支化双（三联吡啶）铁（II）线的一系列“不对称”电位阶跃计时安培法结果。
