Terminal Redox-Site Effect on the Long-Range Electron Conduction of Fe(tpy)2 Oligomer Wires on a Gold Electrode

Authors

  • Shunsuke Katagiri,

    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author
  • Dr. Ryota Sakamoto,

    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author
  • Hiroaki Maeda,

    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author
  • Dr. Yoshihiko Nishimori,

    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author
  • Tomochika Kurita,

    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author
  • Prof. Dr. Hiroshi Nishihara

    Corresponding author
    1. Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    • Department of Chemistry, Graduate School of Science, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan), Fax: (+81) 3-5841-8063
    Search for more papers by this author

  • tpy=2,2′:6′,2′′-Terpyridine.

Abstract

This article completes our comprehensive understanding of the electron transport properties of our original π-conjugated redox-active molecular wires comprising Fe bridged by p-phenylene linkers (tpy=2,2′:6′,2′′-terpyridine). The Fe(tpy)2 oligomer wires comprise three types of tpy ligands: the anchor tpy ligand (A series) makes a junction between the wire and electrode, the bridging bis-tpy ligand (L series) connects the Fe(tpy)2 units, and the terminal tpy ligand (T series) possesses a redox site as a probe for the long-range electron transport ability. Taking advantage of the precise tunability of the composition of the Fe(tpy)2 oligomer wires, thus far we investigated how A and L impacted on the electron-transport ability. The excellent long-range electron transport ability with ultrasmall attenuation constants (βd, 0.002 Å−1 as the minimum) depends on L significantly [Chem. Asian J. 2009, 4, 1361], whereas A is unrelated to the βd value, but influences the zero-distance electron-transfer rate constant, ket0 [J. Am. Chem. Soc. 2010, 132, 4524]. Herein we study the influence of terminal ligand Tx (x=1–3). βd is independent of T, however, T3, with a cyclometallated Ru complex as the redox site, gives rise to a ket0 value greater than T1 and T2 with ferrocene. This series of simple but definitive conclusions indicates that we have reached the stage of being able to precisely design molecular wires to attain desirable single-molecule electron conduction.

Ancillary