Tuning the electrical conductance of metalloporphyrin supramolecular wires

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Noori, Mohammed ; Aragones, Albert C. ; Di Palma, Giuseppe ; Darwish, Nadium ; Bailey, Steven W.D. ; Al-Galiby, Quisy ; Grace, Iain ; Amabilino, David B. ; Gonzalez-Campo, Arántzazu ; Díez-Pérez, Ismael ; Colin J., Lambert (2016)
  • Publisher: Nature Publishing Group
  • Journal: Scientific Reports, volume 6 (issn: 2045-2322, eissn: 2045-2322)
  • Related identifiers: doi: 10.1038/srep37352, pmc: PMC5116753
  • Subject: Article

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 2.10−2 G0 for Ni-DPP up to 8.10−2 G0 for 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.
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    hTis work is supported by UK EPSRC grants EP N017188/1, EP/M014452/1, the European Union Marie-Curie Network MOLESCO 606728 and the Ministry of Higher Education and Scientific Research, Thi-Qar University, IRAQ. I.D.-P. thanks the MINECO Spanish national projects CTQ2012-36090, CTQ2015-71406-ERC and RYC2011-07951, and the EU Reintegration Grant FP7-PEOPLE-2010-RG-277182 for nfiancial support. A.C.A. thanks the Spanish Ministerio de Educación, Cultura y Deporte for a graduate FPU fellowship. N.D. acknowledges the European Union for a Marie Curie IIF Fellowship. A.G.-C. thanks the MICINN Spanish national project MAT2013-47869-C4-P-2, nfiancial support through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496) and the JAE-DOC program (CSIC). DA thanks the EPSRC.

    © The Author(s) 2016

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