Conducting redox polymers: investigations of polythiophene-Ru(bpy)3n+ hybrid materials.

A series of thiophene-appended RuII(bpy)3 derivs., Ru(1)3, Ru(2)3, Ru(3)3, Ru(bpy)2(1), Ru(bpy)2(2), and their resulting polymers were synthesized and characterized. The bpy ligands 5,5′-bis(5-(2,2′-bithienyl))-2,2′-bipyridine (1), 4,4′-bis(5-(2,2′-bithienyl))-2,2′-bipyridine (2), and 4-(5-(2,2′-bithienyl))-2,2′-bipyridine (3), all contain electrochem. polymerizable bithienyl moieties. The monomers Ru(2)3, Ru(3)3, Ru(bpy)2(1) and Ru(bpy)2(2) display spectroscopic features that are similar to the ligand-based and MLCT [metal-to-ligand charge-transfer] bands found for Ru(bpy)3. The cyclic voltammograms of all of these polymers display both metal-centered and thiophene-based electroactivity. High redox cond. was found in poly(Ru(2)3) and poly(Ru(3)3) for both the thiophene-based oxidn. and metal-based redn. processes. These results indicate that the polymers display charge localization for both the metal complexes and the tetrathienyl connecting units. The degree of interconnection (no. of linkages) and the substitution pattern were found to control the cond. of these polymers. The highest cond. (3.3 × 10-3 S cm-1) was found for poly(Ru(2)3), which is able to have up to 6 linkages with other ruthenium complexes and possessing a 4,4′-substitution pattern that allows effective orbital overlap of the conjugated polymer backbone with the ruthenium centers. [on SciFinder(R)]