title: Probing the Conductance of the σ-System of Bipyridine Using Destructive Interference.
abstract: Guidelines to predict trends in the electrical conductance of molecules have been developed for the π-system of conjugated systems. Little is known, however, about the conductance of the underlying σ-systems because the π-system usually dominates the transport. Here we study a family of bipyridine-based molecules using STM-break junction experiments and density functional theory transport calculations. We use different lengths and substitution patterns to probe the role of both the σ-system and the π-system in controlling conductance. By exploiting the destructive interference feature found in the π-system of the meta-coupled six-membered aromatic rings, we show that the conductance of the σ-system of a meta-coupled molecule can be probed directly and can even exceed that of its para-coupled analog. These results add to the understanding of the conductance through the chemically hidden σ-electrons.
authors.affiliation: Nano-Science Center and Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Borges
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: E-Dean
authors.initials: ED
authors.lastname: Fung
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Fay
authors.initials: F
authors.lastname: Ng
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.|Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Latha
authors.initials: L
authors.lastname: Venkataraman
authors.affiliation: Nano-Science Center and Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø, Denmark.
authors.forename: Gemma C
authors.initials: GC
authors.lastname: Solomon