Surface Junction Effects on the Electron Conduction of Molecular Wires

Surface junction effects on the electron conduction of p-phenylene-bridged bis(terpyridine)iron oligomers terminated with a ferrocene moiety were quantitatively analyzed by employing three different surface-anchoring terpyridine ligands. The dependence of the electron-transfer rate constant for oxidation of the ferrocene moiety, ket, on the distance between the electrode surface and the ferrocene moiety, x, showed that the attenuation factor, βd, which indicates the degree of reduction of ket with x, was ∼0.018 in all cases. However, the absolute ket value depended strongly on both electronic and steric factors of the surface-anchoring ligand.