title: Electron transport dynamics in redox-molecule-terminated branched oligomer wires on Au(111).
abstract: 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.
authors.affiliation: Department of Chemistry, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Sakamoto
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Katagiri
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Maeda
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Nishimori
authors.forename: Seiji
authors.initials: S
authors.lastname: Miyashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishihara