Synthesis and characterization of new thiophenebenzimidazole-based electrochromes

In the present study, two new donor-acceptor-donor-type molecules were synthesized and the electro-optical properties of the resulting monomers and their corresponding polymers were investigated. Thiophene was selected as the donor unit and cycloheptyl- and cyclooctyl- substituted benzimidazoles were used as the acceptor units. The synthesized monomers and their electrochemically obtained polymers were characterized using cyclic voltammetry and UV-Vis spectrometry. The optical band gap values of the polymers were 1.62 eV and the polymer films changed color to gray upon oxidation, while they were brick red in their neutral states. Moreover, changing the ring size on the acceptor group from seven carbon to eight carbon did not result in any differences in the electrochemical or optical properties of the resulting polymers. Moreover, the effect of the acceptor unit was also investigated by comparing the polymers in this work with other polymers bearing thiophene and benzimidazole