Synthesis and Photophysical Properties of New 2,2′‐Bipyridine‐Bridged Bis[ruthenium(II)tris‐2,2′‐bipyridine] Complexes

Abstract We have synthesized a new type of tris‐2,2'‐bipyridine ligand with 4,4'‐ and 6,6'‐disubstituted 2,2'‐bipyridine (bpy) units. The terminal 4,4'‐and 6,6'‐disubstituted 2,2'‐bipyridine moieties are selectively coordinated by Ru(bpy)2 (bpy = 2,2′‐bipyridine), whereas the central 2,2′‐bipyridine ligand does not participate in any metal ion coordination. The two Ru(bpy)3 units of 7 and 8 do not interact appreciably, as is evident from their electrochemical and photophysical data. The lifetime of the excited state of compound 7 at 77 K is similar to that of Ru(bpy)2(4,4′‐dimethyl‐2,2′‐bipyridine), whereas that of compound 8 under the same conditions is comparatively long.