title: Quasi-ohmic single molecule charge transport through highly conjugated meso-to-meso ethyne-bridged porphyrin wires.
abstract: Understanding and controlling electron transport through functional molecules are of primary importance to the development of molecular scale devices. In this work, the single molecule resistances of meso-to-meso ethyne-bridged (porphinato)zinc(II) structures (PZn(n) compounds), connected to gold electrodes via (4'-thiophenyl)ethynyl termini, are determined using scanning tunneling microscopy-based break junction methods. These experiments show that each α,ω-di[(4'-thiophenyl)ethynyl]-terminated PZn(n) compound (dithiol-PZn(n)) manifests a dual molecular conductance. In both the high and low conductance regimes, the measured resistance across these metal-dithiol-PZn(n)-metal junctions increases in a near linear fashion with molecule length. These results signal that meso-to-meso ethyne-bridged porphyrin wires afford the lowest β value (β = 0.034 Å(-1)) yet determined for thiol-terminated single molecules that manifest a quasi-ohmic resistance dependence across metal-dithiol-PZn(n)-metal junctions.
authors.affiliation: Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States.
authors.forename: Zhihai
authors.initials: Z
authors.lastname: Li
authors.forename: Tae-Hong
authors.initials: TH
authors.lastname: Park
authors.forename: Jeff
authors.initials: J
authors.lastname: Rawson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Therien
authors.forename: Eric
authors.initials: E
authors.lastname: Borguet
mesh_terms: D004553:Electric Conductivity; D004579:Electron Transport; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D011166:Porphyrins