Electrochemically Controlled 2D Assembly of Paddle-Wheel Diruthenium Complexes on the Au(111) Surface and Identification of Their Redox States

Abstract

The 2D molecular assemblies of chloride-coordinated mixed-valence diruthenium complexes, each possessing phenyl, naphtyl, or anthracenyl moieties, were examined on an Au(111) at electrochemical interface. In situ scanning tunneling microscopy images revealed a clear dependence of the molecular assembly on both the nature of the aryl functional groups and on the redox state of the dinuclear ruthenium complex, either chloride-coordinated Ru^II/Ru^III or noncoordinated Ru^II/Ru^II. At potentials where the Ru^II/Ru^III and Ru^II/Ru^II redox states were in equilibrium, two distinct redox states were clearly identified at the single-molecular level. We found that manipulating both the electrochemical potential and the aryl functional group substitution was important for controlling the 2D molecular assembly of a chloride-coordinated diruthenium complex on an Au(111) surface