title: Fine-tuning of single-molecule conductance by tweaking both electronic structure and conformation of side substituents.
abstract: Herein, we describe a method to fine-tune the conductivity of single-molecule wires by employing a combination of chemical composition and geometrical modifications of multiple phenyl side groups as conductance modulators embedded along the main axis of the electronic pathway. We have measured the single-molecule conductivity of a novel series of phenyl-substituted carotenoid wires whose conductivity can be tuned with high precision over an order of magnitude range by modulating both the electron-donating character of the phenyl substituent and its dihedral angle. It is demonstrated that the electronic communication between the phenyl side groups and the molecular wire is maximized when the phenyl groups are twisted closer to the plane of the conjugated molecular wire. These findings can be refined to a general technique for precisely tuning the conductivity of molecular wires.
authors.affiliation: Physical-Chemistry Department, University of Barcelona and the Institute for Bioengineering of Catalonia, Diagonal 645, 08028 Barcelona (Spain).
authors.forename: Albert C
authors.initials: AC
authors.lastname: Aragonès
authors.forename: Nadim
authors.initials: N
authors.lastname: Darwish
authors.forename: JongOne
authors.initials: J
authors.lastname: Im
authors.forename: Boram
authors.initials: B
authors.lastname: Lim
authors.forename: Jeongae
authors.initials: J
authors.lastname: Choi
authors.forename: Sangho
authors.initials: S
authors.lastname: Koo
authors.forename: Ismael
authors.initials: I
authors.lastname: Díez-Pérez
mesh_terms: D002338:Carotenoids / Q000737:chemistry*; D004553:Electric Conductivity; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology; D011789:Quantum Theory
chemical_list: D002338:Carotenoids
keywords: STM break junction; carotenoids; conductance; self-assembly; single-molecule studies