Synthesis and tuning of chemical properties by protonation/deprotonation of novel dinuclear ruthenium complexes containing 2,6,2′,6′-tetra(4,5-dimethylbenzimidazol-2-yl)-4, 4′-bipyridine

A novel dinuclear ruthenium complex, [(tpy)Ru(tmbimbpyH4)Ru(tpy)](ClO4)4, has been synthesized to introduce a new proton-induced molecular switching system, where tpy=2,2′:6′,2″-terpyridine and tmbimbpyH4=2,6,2′,6′-tetra(4,5-dimethylbenzimidazol-2-yl)-4,4′-bipyridine. Both fully protonated and deprotonated forms of the dinuclear Ru complex were isolated and the forms were interchangeable by the addition of acid or base. A longer wavelength shift and a negative oxidation potential shift were observed when the protonated Ru complex was fully deprotonated.