Controlled Incorporation of Silver Atoms into Coordination Chain Single-Molecule Junctions Formed on Gold Electrodes.

Abstract

Enhancing the functionality of molecular junctions through control over the electrode composition, molecular anchor groups, and metal-molecule coupling remains a central goal in advancing molecular electronics. Here, we introduce silver species onto gold electrodes to construct bimetallic coordination bridges of the form (Im^--M)_<i>n</i> (<i>n</i> = 1 and 2), where M = Ag or Au, using imidazolate (Im^-) ligands, and to investigate their transport properties. Through electrochemical control, we systematically modulate the incorporation of silver and observe a corresponding conductance suppression with an increasing concentration of Ag⁺. Our experimental measurements and density functional theory (DFT)-based calculations reveal that the decreased density of d-states on silver reduces the orbital coupling between the molecular HOMO and silver-tipped gold electrodes, leading to lower transport. Overall, this work determines that weakened metal-molecule coupling is responsible for conductance reduction of imine-terminated molecules on silver and establishes a generalizable approach for incorporating transition metal atoms into molecular circuits in ambient environments.