Structure and spectroelectrochemical property of a ruthenium complex containing phenanthroline–quinone, and assembly of the complexes on a gold electrode

Ruthenium complexes containing pdon (pdon = 1,10-phenanthroline-5,6-dione) were synthesized. Their spectroscopic and electrochemical properties were examined. The molecular structure with [Ru(pdon)(bpy)2](ClO4)2 ([1](ClO4)2) (bpy = 2,2′-bipyridyl) was determined by single crystal X-ray diffraction. The optically transparent thin-layer electrochemical measurements confirm that the quinone form of [1](ClO4)2 is reduced to the semi-quinone state in acetonitrile (E°′ = −8 mV). Comparing the model complex, [1](ClO4)2, and metal-free pdon, the positive charge on two carbon atoms of the o-quinone group is bigger than that of metal-free pdon. The assemblies of the complexes were finally examined using ligand substitution.