Temperature and length dependence of charge transport in redox-active molecular wires incorporating ruthenium (II) bis (σ-arylacetylide) complexes.

Abstract : Understanding of charge transport through org. or inorganometallic mol. wires is a central issue in mol. electronics. In particular, fundamental issues such as the mol. structure-transport relationships and the mol. length dependence must be addressed. We report the elec. transport behavior of a series of redox-active conjugated mol. wires (Ru1 - Ru3) as a function of temp. and mol. length. The mols. were self-assembled and their films were extensively characterized using cyclic voltammetry, ellipsometry, XPS, and IR spectroscopy. Their elec. properties were examd. by conducting probe at. force microscopy and crossed-wire junctions. At room temp., we find a very weak dependence of the wire resistance with mol. length (β = 0.09/Å), consistent with a high degree of electronic communication along the mol. backbone. In low temp. (5 K) expts., Coulomb blockade-like behavior was obsd. in junctions incorporating Ru3 whereas direct tunneling apparently occurs through Ru1 and Ru2. [on SciFinder(R)]