jp4100262_si_001.pdf (1.14 MB)
Additive Electron Pathway and Nonadditive Molecular Conductance by Using a Multipodal Bridging Compound
journal contribution
posted on 2014-03-13, 00:00 authored by Manabu Kiguchi, Yuuta Takahashi, Shintaro Fujii, Masayoshi Takase, Tomoyuki Narita, Masahiko Iyoda, Masayo Horikawa, Yasuhisa Naitoh, Hisao NakamuraWe designed and synthesized a new
quadrivial anchoring unit 4-TEB, to construct a stable
single-molecule junction with
gold electrodes, which should have equivalent conducting electron
pathways between two electrodes. The conductances of single-molecule
junctions comprising 4-TEB and its bidirectional counterpart 2-TEB were determined to be 2.7 × 10–4G0 (2e2/h) and 5.0 × 10–5G0, respectively, by using scanning tunneling microscope
break junction (STM-BJ) techniques. The single 4-TEB molecule
junction had higher stability and conductivity compared to those of
the single 2-TEB molecule junction. Although the number
of electron pathways from/to the electrode to/from the molecule was
additive using the equivalent multianchoring, the conductance of the
single-molecule junction was not additive. From first-principles electronic
transport calculations, the mechanism for the new quadrivial 4-TEB single-molecule junction involved an overlap resonance
effect to the HOMO conducting orbital, giving rise to tunneling. Using
fixed nanogap electrodes, we constructed stable molecular junctions
of 4-TEB and observed symmetric peaks in the derivative
of the conductance–voltage (G–V) curves,
which were assigned to electron transport through the HOMO on the
basis of theoretical calculations.