Synthesis and electropolymerization of tetra-[β-(2-benzimidazole)] and tetra-[β-(2-(1-(4- aminophenyl))benzimidazole)] embedded cobalt phthalocyanine and their supercapacitance behaviour

Abstract Novel polar, electroactive N4 macrocycle with four benzimidazole units covalently substituted to the periphery of the Cobalt(II)phthalocyanine complexes have been reported for the first time. Cobalt phthalocyanine with tetra[β-(2-benzimidazole)] and tetra[β-(2-(1-(4-aminophenyl))benzimidazole)] substituted complexes were synthesized from cobalt-tetra[β-(carboxylicacid)]phthalocyanine. Dark green coloured complexes were characterized by elemental analysis, UV-Vis, FT-IR, and X-ray powder diffraction for their purity. Thermal stability studies of these newly synthesized complexes revealed that these complexes are thermally highly stable. Electrochemical properties of the synthesized phthalocyanines were determined by cyclic voltammetry. CoII metal ion in the core of the cobalt-tetra [β-(2-benzimidazole)]phthalocyanine and cobalt-tetra[β-(2-(1-(4-aminophenyl))benzimidazole)] phthalocyanine complexes showed redox active behavior. Benzimidazole ring and –NH2 group in the complexes undergoes electrochemical polymerization on the working electrode during the positive potential sweeps. Electrochemical measurements of the monomer and polymeric films showed two redox couples which are assigned to the metal and ligand. The influence of reduced grapheneoxide intercalation on the supercapacitance behavior of the electropolymerized films has been studied and their supercapacitance values have been reported.