title: Tuning the electrical conductance of metalloporphyrin supramolecular wires.
abstract: In contrast with conventional single-molecule junctions, in which the current flows parallel to the long axis or plane of a molecule, we investigate the transport properties of M(II)-5,15-diphenylporphyrin (M-DPP) single-molecule junctions (M=Co, Ni, Cu, or Zn divalent metal ions), in which the current flows perpendicular to the plane of the porphyrin. Novel STM-based conductance measurements combined with quantum transport calculations demonstrate that current-perpendicular-to-the-plane (CPP) junctions have three-orders-of-magnitude higher electrical conductances than their current-in-plane (CIP) counterparts, ranging from 2.10-2G0for Ni-DPP up to 8.10-2G0for Zn-DPP. The metal ion in the center of the DPP skeletons is strongly coordinated with the nitrogens of the pyridyl coated electrodes, with a binding energy that is sensitive to the choice of metal ion. We find that the binding energies of Zn-DPP and Co-DPP are significantly higher than those of Ni-DPP and Cu-DPP. Therefore when combined with its higher conductance, we identify Zn-DPP as the favoured candidate for high-conductance CPP single-molecule devices.
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.|Department of Physics, Collage of Science, Thi-Qar University, Iraq.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Noori
authors.affiliation: Department of Physical Chemistry, University of Barcelona, Diagonal 645, Spain.|Institute for Bioengineering of Catalonia (IBEC) Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain.|Centro Investigación Biomédica en Red (CIBER-BBN). Campus Río Ebro-Edificio I+D, Poeta Mariano Esquillor s/n, 50018 Zaragoza, Spain.
authors.forename: Albert C
authors.initials: AC
authors.lastname: Aragonès
authors.affiliation: Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus Universitari, 08193 Bellaterra, Catalonia, Spain.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Di Palma
authors.affiliation: Department of Physical Chemistry, University of Barcelona, Diagonal 645, Spain.|Institute for Bioengineering of Catalonia (IBEC) Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain.
authors.forename: Nadim
authors.initials: N
authors.lastname: Darwish
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Steven W D
authors.initials: SW
authors.lastname: Bailey
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.|Physics Department, College of Education, Al-Qadisiyah University, Iraq.
authors.forename: Qusiy
authors.initials: Q
authors.lastname: Al-Galiby
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Iain
authors.initials: I
authors.lastname: Grace
authors.affiliation: School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: David B
authors.initials: DB
authors.lastname: Amabilino
authors.affiliation: Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus Universitari, 08193 Bellaterra, Catalonia, Spain.
authors.forename: Arántzazu
authors.initials: A
authors.lastname: González-Campo
authors.affiliation: Department of Physical Chemistry, University of Barcelona, Diagonal 645, Spain.|Institute for Bioengineering of Catalonia (IBEC) Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain.|Centro Investigación Biomédica en Red (CIBER-BBN). Campus Río Ebro-Edificio I+D, Poeta Mariano Esquillor s/n, 50018 Zaragoza, Spain.
authors.forename: Ismael
authors.initials: I
authors.lastname: Díez-Pérez
authors.affiliation: Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Lambert
mesh_terms: D003035:Cobalt / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D004553:Electric Conductivity; D004563:Electrochemistry; D008665:Metalloporphyrins / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D008665:Metalloporphyrins; D003035:Cobalt; D003300:Copper; D009532:Nickel; D015032:Zinc