Single Molecule Conductance of Linear Dithioalkanes in the Liquid Phase: Apparently Activated Transport Due to Conformational Flexibility
Author(s):
Daniel R. Jones, Alessandro Troisi
Journal:
The Journal of Physical Chemistry C
Year:
2007
Volume:
111
Pages
14567-14573
DOI:
10.1021/jp074351c
Abstract:
We computed the single molecule conductance of a series of linearR-ˆ-dithiolalkanes as a function of theirconformation, following experimental evidence (Haiss et al.Faraday Discuss.2006,131, 253) that eventhese simple molecules exhibit a thermal gating of electron transfer. After performing a conformational searchusing the MM3 empirical force-field, for each conformation, we evaluated the conductance using DFT singlepoint calculations and Green’s function theoretical approach. We analyzed the complex dependence of theconductance on the conformation, discussing its correlation with the conformational energy and the moleculeend-to-end distance. From this data, the temperature dependence of conductance was calculated. Our calculationsconfirm that the conformational flexibility of the alkylic chain led to a higher conductance at highertemperatures. Therefore, the electron transport in these junctions appears to be thermally activated even if ittakes place by pure tunneling.