Trimethylsilyl-Terminated Oligo(Phenylene Ethynylene)s: An Approach to Single-Molecule Junctions with Covalent Au–C σ-Bonds.

A new and efficient approach using cleaving of trimethylsilyl groups to create covalent Au–C anchoring sites has been developed for single-molecule junction conductance measurements. Employing the mechanically controllable break junction (MCBJ) technique in liquid, we demonstrate the formation of highly conducting single molecular junctions of several OPE derivatives. The created junctions are mechanically stable and exhibit conductances around one order of magnitude higher than those of their dithiol analogues. Extended assembly and reaction times lead to oligomerization. Combined STM imaging and gap-mode Raman experiments provide structure evidence to support the formation of covalent Au–C contacts and further oligomerization.