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Influence of conformational flexibility on single-molecule conductance in nano-electrical junctions

Influence of conformational flexibility on single-molecule conductance in nano-electrical junctions
Influence of conformational flexibility on single-molecule conductance in nano-electrical junctions
The temperature dependence of the single molecule conductance of conformationally flexible alkanedithiol molecular bridges is compared to that of more rigid analogs which contain cyclohexane ring(s). Molecule conductance has been measured with a scanning tunneling microscope (STM) at fixed gap separation by observing the stochastic formation of molecule bridges between a gold STM tip and substrate (the so-called “I(t)” technique). Under these conditions the junction can be populated by a wide distribution of conformers of alkanedithiol molecular bridges and a strong temperature dependence of the single molecule conductance is observed. By contrast the rigid analogs that contain cyclohexane ring(s), which cannot form the thermally accessible gauche rich conformers open to the alkanedithiols, show no dependence of the single molecule conductance on temperature. This comparison demonstrates that it is the conformational flexibility and access to thermally populated higher energy conformers of the linear polymethylene (alkane) bridges which leads to the temperature dependence. By removing this possibility in the cyclohexane ring containing bridges this conformational gating is excluded and the temperature dependence is then effectively suppressed.
1932-7447
18884-18890
Martin, Santiago
cd632ff6-2cbf-4904-b50d-a8b49eb24117
Giustiniano, Francesco
f2692f6a-8f0a-49de-aa5d-7c2dff402545
Haiss, Wolfgang
b4634393-d103-493f-b272-71914ad777e2
Higgins, Simon J.
d19c4ed5-66a9-4360-a806-41e67a8b19e0
Whitby, Richard J.
45632236-ab00-4ad0-a02d-6209043e818b
Nichols, Richard J.
7eb6914e-83ee-4aa0-9464-b349bb465cf3
Martin, Santiago
cd632ff6-2cbf-4904-b50d-a8b49eb24117
Giustiniano, Francesco
f2692f6a-8f0a-49de-aa5d-7c2dff402545
Haiss, Wolfgang
b4634393-d103-493f-b272-71914ad777e2
Higgins, Simon J.
d19c4ed5-66a9-4360-a806-41e67a8b19e0
Whitby, Richard J.
45632236-ab00-4ad0-a02d-6209043e818b
Nichols, Richard J.
7eb6914e-83ee-4aa0-9464-b349bb465cf3

Martin, Santiago, Giustiniano, Francesco, Haiss, Wolfgang, Higgins, Simon J., Whitby, Richard J. and Nichols, Richard J. (2009) Influence of conformational flexibility on single-molecule conductance in nano-electrical junctions. The Journal of Physical Chemistry C, 113 (43), 18884-18890. (doi:10.1021/jp906763p).

Record type: Article

Abstract

The temperature dependence of the single molecule conductance of conformationally flexible alkanedithiol molecular bridges is compared to that of more rigid analogs which contain cyclohexane ring(s). Molecule conductance has been measured with a scanning tunneling microscope (STM) at fixed gap separation by observing the stochastic formation of molecule bridges between a gold STM tip and substrate (the so-called “I(t)” technique). Under these conditions the junction can be populated by a wide distribution of conformers of alkanedithiol molecular bridges and a strong temperature dependence of the single molecule conductance is observed. By contrast the rigid analogs that contain cyclohexane ring(s), which cannot form the thermally accessible gauche rich conformers open to the alkanedithiols, show no dependence of the single molecule conductance on temperature. This comparison demonstrates that it is the conformational flexibility and access to thermally populated higher energy conformers of the linear polymethylene (alkane) bridges which leads to the temperature dependence. By removing this possibility in the cyclohexane ring containing bridges this conformational gating is excluded and the temperature dependence is then effectively suppressed.

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More information

Published date: 29 October 2009
Organisations: Chemistry

Identifiers

Local EPrints ID: 147747
URI: http://eprints.soton.ac.uk/id/eprint/147747
ISSN: 1932-7447
PURE UUID: 6507a97c-f955-4fcd-bc70-bc9356738c9d
ORCID for Francesco Giustiniano: ORCID iD orcid.org/0000-0001-9277-8538
ORCID for Richard J. Whitby: ORCID iD orcid.org/0000-0002-9891-5502

Catalogue record

Date deposited: 26 Apr 2010 14:36
Last modified: 29 Oct 2019 02:11

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