Electrochemical polymerization at an electrode surface: Film formation of the Ni(II) complex of dibenzo [ b, i] [1,4,8,11]tetraaza[14]annulene and the Ni(II) and Cu(II) complexes of 5,7,12,14-tetramethyldibenzo[ b, i][1,4,8,11]tetraaza[14]annulene: Copolymerization and layered polymerization

Abstract

The detailed mechanistic nature of the electropolymerization of metal complexes of 5,7,12,14- tetramethyldibenzo[ b, i][1,4,8,11]tetraaza[14]annulene has been investigated at electrode surfaces. Polymerization was not observed if the second oxidation wave in the cyclic voltammogram was not scanned. The quantity of film deposition was shown to vary as a function of the percentage of the second oxidation wave scanned. An upper limit for deposition of film was reached at +1.4 V versus SCE. Copolymerization of both copper(II) and nickel(II) 5,7,12,14-tetramethyldibenzo[ b, i][1,4,8,11]tetraaza[14]annulene showed no effect on the rate of polymerization due to the metal center. However, copolymerization of 5,7,12,14-tetramethyldibenzo- [ b, i][1,4,8,11]tetraaza[14]annulene copper(II) and dibenzo[ b, i][1,4,8,11]tetraaza[14]annulene nickel(II) showed that the methyl groups decreased the polymerization rate by a factor of ∼6. Layered films of these complexes showed that the outer layer of film controls the redox properties at the electrode. Following the electrochemical features of ferrocyanide and 1,4-benzoquinone, it was possible to show that electrochemical activity through thinner films is possible but is inhibited by films that are at least 55 monolayers thick. Studies of effects on the electrochemical behavior of films due to the presence of fluoride, pyridine and cyanide were carried out.