Electropolymerization of [2 × 2] grid-type cobalt(II) complex with thiophene substituted dihydrazone ligand

Abstract The grid-type complex [Co4(L1-2H)4] containing dihydrazone ligand decorated with thiophene rings has been prepared. The complex undergoes oxidative electropolymerization onto ITO electrode to form purple thin film. The morphology of polymer film on ITO electrode was analyzed by SEM and AFM imagining. It was found that polymer obtained by electropolymerization method is homogenous and uniform. The obtained thin film exhibits color transition from purple via violet to blue due to the stepwise reduction of poly-[CoII4(L1-2H)4] into poly-[CoII2CoI2(L1-2H)4]2− and poly-[CoI4(L1-2H)4]4−. Its electrochromic properties such as long-term stability coloration efficiency and switching times have been investigated.