As connectors between various molecular devices, molecular wires play a crucial role in achieving molecular electrocircuit. Molecular wires are quasi-linear molecules that allow charge carriers (electronics or holes) to transport along the molecular backbones. They are crucial components to achieve the communication between molecular devices and the linkage between molecular devices and macro-electrodes so that molecular electrocircuits can be operating.

Prof. CHEN Zhongning’s research group at Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences, has reported single-molecule conductance of three sulphur-functionalized organometallic wires with two ruthenium(II) centres spaced by 1,3-butadiyne using an electrochemically assisted-mechanically controllable break junction (EC-MCBJ) approach.

These works were accomplished through cooperation with Prof. TIAN Zhongqun’s research group at the State Key Lab for Physical Chemistry of Solid Surfaces, Xiamen University. It is demonstrated that single-molecule conductance of these diruthenium(II) incorporated systems is significantly higher than oligo(phenylene-ethynylene) (OPE) having comparable lengths and exhibits weaker length dependence.

The conductance improvement in these diruthenium(II) molecules is ascribable to the better energy match of the Femi level of gold electrodes with the HOMO that is mainly resident on Ru–C≡C–C≡C–Ru backbone. Furthermore, modulation of molecular conductance is achieved by changing the length and π-conjugated system of chelating 2,2’:6’,2’’-terpyridyl ligand.

Results of this study have been published in Chemical Science (DOI:10.1039/C3SC50312G ).