Spectroscopic and electrochemical properties of ruthenium(II) polypyridyl complexes

Luminescent mixed-ligand ruthenium(II) complexes of type [Ru(bpy)(2)L](2+) (where bpy=2,2'-bipyridine, L=3,3'-dicarboxy-2,2'-bipyridine 1; 4,4'-dicarb oxy-2,2'-bipyridine 2; or 5,5'-dicarboxy-2,2'-bipyridine 3) were synthesize d. Their photophysical, acid-base and electrochemical properties were inves tigated. The emission lifetime for 2 was the longest, and the emission quan tum yield was the highest for 2. This reveals that the positions of the car boxylic acids in the 2,2'-bipyridine ligand had an important influence on t he photophysical and electrochemical properties of the complexes.