Conductance of Well-Defined Porphyrin Self-Assembled Molecular Wires up to 14 nm in Length
2014-04-03T00:00:00Z (GMT) by
We show that molecular wires up to 14 nm in length composed by zinc-porphyrins bridged by bipyridines stand efficient electrical transport. Self-assembled molecular wires were prepared step-by-step, alternating up to 13 units of zinc-octaethylporphyrin with axially coordinated 4,4′-bipyridine, on highly oriented pyrolytic graphite (HOPG). A combination of molecular resolution imaging and scanning tunneling spectroscopy allowed us to follow molecules self-assembly in real time during wire fabrication and to measure wires current, respectively. A statistical analysis of hundreds of current–voltage curves was carried out to determine the conductance of individual porphyrin/bipyridine wires. From the conductance dependence on the wires length an ultra low attenuation factor (β = 0.015 ± 0.006 Å–1) was obtained for shorter wires, with a transition in conduction regime occurring at ca. 6.5 nm long wires.
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