Proton controlled intramolecular communication in dinuclear ruthenium(II) polypyridine complexes

The synthesis and characterization of two dinuclear ruthenium polypyridyl complexes based on the bridging ligands 5,5'-bis(pyridin-2' '-yl)-3,3'-bis(1H-1,2,4-triazole) and 5,5'-bis(pyrazin-2' '-yl)-3,3'-bis(1H-1,2,4-triazole) and of their mononuclear precursors are reported. The dinuclear compounds have been prepared by a Ni(0) catalyzed coupling of a mononuclear ruthenium(II) polypyridyl complex containing a brominated triazole moiety. Electrochemical and photophysical studies indicate that, in these dinuclear complexes, the protonation state of the bridge may be used to tune the intercomponent interaction between the two metal centers and that these species act as proton driven three-way molecular switches that can be read by electrochemical or luminescence techniques.