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Abstract
Metal complexes are receiving increased attention as molecular wires in fundamental studies of the transport properties of metalmoleculemetal junctions. In this context we report the single-molecule conductance of a systematic series of d8 square-planar platinum(ii) trans-bis(alkynyl) complexes with terminal trimethylsilylethynyl (CCSiMe3) contacting groups, e.g. trans-Pt{CCC6H4CCSiMe3}2(PR3)2 (R = Ph or Et), using a combination of scanning tunneling microscopy (STM) experiments in solution and theoretical calculations using density functional theory and non-equilibrium Green's function formalism. The measured conductance values of the complexes (ca. 3-5 × 10-5G0) are commensurate with similarly structured all-organic oligo(phenylene ethynylene) and oligo(yne) compounds. Based on conductance and break-off distance data, we demonstrate that a PPh3 supporting ligand in the platinum complexes can provide an alternative contact point for the STM tip in the molecular junctions, orthogonal to the terminal CCSiMe3 group. The attachment of hexyloxy side chains to the diethynylbenzene ligands, e.g. trans-Pt{CCC6H2(Ohex)2CCSiMe3}2(PPh3)2 (Ohex = OC6H13), hinders contact of the STM tip to the PPh3 groups and effectively insulates the molecule, allowing the conductance through the full length of the backbone to be reliably measured. The use of trialkylphosphine (PEt3), rather than triarylphosphine (PPh3), ancillary ligands at platinum also eliminates these orthogonal contacts. These results have significant implications for the future design of organometallic complexes for studies in molecular junctions.
Original language | English |
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Pages (from-to) | 9902-9912 |
Number of pages | 11 |
Journal | Nanoscale |
Volume | 9 |
Issue number | 28 |
DOIs | |
Publication status | Published - 28 Jul 2017 |
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Dive into the research topics of 'Insulated molecular wires: Inhibiting orthogonal contacts in metal complex based molecular junctions'. Together they form a unique fingerprint.Projects
- 3 Finished
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Enhancing Scanning Probe Microscopy in Western Australia: High resolution, soft imaging and electrochemical Scanning Probe Microscopy
Low, P. (Investigator 01), Becker, T. (Investigator 02), Clode, P. (Investigator 03), Koutsantonis, G. (Investigator 04), Swaminatha Iyer, I. (Investigator 05), Gale, J. (Investigator 06), Karton, A. (Investigator 07), Arrigan, D. (Investigator 08) & Ogden, M. (Investigator 09)
ARC Australian Research Council , Curtin University
1/01/15 → 31/12/16
Project: Research
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From the Electronics of Molecules to Molecular Electronics
Low, P. (Investigator 01) & Nichols, R. (Investigator 02)
ARC Australian Research Council
1/01/14 → 31/12/17
Project: Research
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From Beaker to Bit: New Platforms for Molecular Electronics
Low, P. (Investigator 01)
ARC Australian Research Council
1/01/12 → 30/06/17
Project: Research