FORMATION OF THIN POLYMERIC FILMS BY ELECTROPOLYMERIZATION - REDUCTION OF METAL-COMPLEXES CONTAINING BROMOMETHYL-SUBSTITUTED DERIVATIVES OF 2,2'-BIPYRIDINE

Polypyridyl complexes of Fe(II) and Ru(II) containing the ligands 4,4'-bis(bromomethyl)-2,2'-bipyridine or 4-(bromomethyl)-4'-methyl-2,2'-bipyridine have been prepared. Upon electrochemical reduction of the complexes, coupling reactions occur at the ligands that yield thin, metal-complex containing, polymeric films on electrode surfaces. The coupling reaction was also found to occur for the free ligand to give an electrode coated with a thin, poly(bipyridine) film. When exposed to a solution containing FeCl2, these films incorporated Fe(II) by forming a tris(bipyridyl) complex. The rates of electropolymerization of the complexes have been studied relative to complexes containing the polymerizable ligand 4-methyl-4'-vinyl-2,2'-bipyridine (vbpy). Films prepared by the electrochemical polymerization of the bromomethyl-substituted, bipyridine-containing complexes appear to be less dense and more permeable than films obtained by electrochemical polymerization of analogous complexes containing the vbpy ligand. Copolymeric films, in which more than one complex is incorporated into a single layer, have been prepared as have "bilayer" films, in which different complexes are spatially separated in separate layers.