Investigation of the formation and selective behavior of thienyl pyridazine electropolymers

Thin-film electrode materials that are selectively redox active as a function of potential are of interest in a number of industries – particularly as sensors or in energy applications. Here we present such a material synthesized from the electropolymerization of a thienyl pyridazine compound, 1,4-di(thiophen-2-yl)-2H-cyclopenta[ d]pyridazine, on a platinum disk electrode from acetonitrile solution. The thienyl pyridazine electropolymer functionalized electrode loses its ability to reversibly oxidize decamethylferrocene, while retaining quasi-reversible oxidation of both ferrocene and acetylferrocene, attributed to their more positive redox potentials. In addition, the thienyl pyridazine electropolymer formed through successive cyclic voltammetric cycles is shown to be comparable to that formed by the method of prolonged applied 1.0 V bias. Electrochemical impedance spectroscopy (EIS) is used in situ to help infer kinetic and mechanistic information of thienyl pyridazine film formation. Finally, it is shown that electropolymerization can be sterically hindered by the presence of a perfluoropyridine group on the thienyl pyridazine monomer at the nitrogen position, showing that electropolymerization can be significantly impacted by changes to the pyridazine center of the monomer.