Solvent dependence of the single molecule conductance of oligoyne-based molecular wires

Milan, David C. and Al-Owaedi, Oday A. and Oerthel, Marie-Christine and Marqués-González, Santiago and Brooke, Richard J. and Bryce, Martin R. and Cea, Pilar and Ferrer, Jaime and Higgins, Simon J. and Lambert, Colin J. and Low, Paul J. and Manrique, David Zsolt and Martin, Santiago and Nichols, Richard J. and Schwarzacher, Walther and García-Suárez, Víctor M. (2016) Solvent dependence of the single molecule conductance of oligoyne-based molecular wires. The Journal of Physical Chemistry C, 120 (29). pp. 15666-15674. ISSN 1932-7447

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Abstract

The conductance and the decay of conductance as a function of molecular length within a homologous series of oligoynes, Me3Si—(C≡C)n—SiMe3 (n = 2, 3, 4, or 5), is shown to depend strongly on the solvent medium. Single molecule junction conductance measurements have been made with the I(s) method for each member of the series Me3Si—(C≡C)n—SiMe3 (n = 2, 3, 4, and 5) in mesitylene (MES), 1,2,4-trichlorobenzene (TCB), and propylene carbonate (PC). In mesitylene, a lower conductance is obtained across the whole series with a higher length decay (β ≈ 1 nm–1). In contrast, measurements in 1,2,4-trichlorobenzene and propylene carbonate give higher conductance values with lower length decay (β ≈ 0.1 and 0.5 nm–1 respectively). This behavior is rationalized through theoretical and computational investigations, where β values are found to be higher when the contact Fermi energies are close to the middle of the HOMO–LUMO gap but decrease as the Fermi energies approach resonance with either the occupied or unoccupied frontier orbitals. The different conductance and β values between MES, PC, and TCB have been further explored using DFT-based models of the molecular junction, which include solvent molecules interacting with the oligoyne backbone. Good agreement between the experimental results and these “solvated” junction models is achieved, giving new insights into how solvent can influence charge transport in oligoyne-based single molecule junctions.

Item Type: Journal Article
Journal or Publication Title: The Journal of Physical Chemistry C
Additional Information: doi: 10.1021/acs.jpcc.5b08877
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/2500/2504
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 82172
Deposited By: ep_importer_pure
Deposited On: 13 Oct 2016 10:54
Refereed?: Yes
Published?: Published
Last Modified: 11 Sep 2019 03:06
URI: https://eprints.lancs.ac.uk/id/eprint/82172

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