Structural versus Electrical Functionalization of Oligo(phenylene ethynylene) Diamine Molecular Junctions

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• 作者：M. Teresa Gonz谩lez ; Xiaotao Zhao ; David Zsolt Manrique ; Delia Miguel ; Edmund Leary ; Murat Gulcur ; Andrei S. Batsanov ; Gabino Rubio-Bollinger ; Colin J. Lambert ; Martin R. Bryce ; Nicol谩s Agra茂t
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：September 18, 2014
• 年：2014
• 卷：118
• 期：37
• 页码：21655-21662
• 全文大小：371K
• ISSN：1932-7455

文摘

We explore both experimentally and theoretically the conductance and packing of molecular junctions based on oligo(phenyleneethynylene) (OPE) diamine wires, when a series of functional groups are incorporated into the wires. Using the scanning tunnelling microscopy break-junction (STM BJ) technique, we study these compounds in two environments (air and 1,2,4-trichlorobenzene) and explore different starting molecular concentrations. We show that the electrical conductance of the molecular junctions exhibits variations among different compounds, which are significant at standard concentrations but become unimportant when working at a low enough concentration. This shows that the main effect of the functional groups is to affect the packing of the molecular wires, rather than to modify their electrical properties. Our theoretical calculations consistently predict no significant changes in the conductance of the wires due to the electronic structure of the functional groups, although their ability to hinder ring rotations within the OPE backbone can lead to higher conductances at higher packing densities.