Electrochemical synthesis of new conjugated polymers based on carbazole and furan units

Abstract

In this study, synthesis of four new monomers; 3,6-di(2-furyl)-9H-carbazole (M1), 3,6-di(2-furyl)-9-ethyl-carbazole (M2), 2,7-di(2-furyl)-9-H-carbazole (M3), 2,7-di(2-furyl)-9-(tridecan-7-yl)-9H-carbazole (M4), was achieved via Stifle cross-coupling reaction. The monomers were electrochemically polymerized, via repetitive cycling in acetonitrile-tetrabutylammonium hexafluorophosphate electrolytic medium. Optical and electrochemical properties of the monomers and their corresponding polymers were investigated and it was found that optical properties show slight variations depending on the connectivity between the carbazole and furan moieties. However, all the monomers synthesized in this work exhibited an irreversible oxidation peak at around 1.0 V. Electrochemically obtained polymer films, on the other hand, exhibited quasi-reversible redox behavior due to doping/dedoping of the polymers which was accompanied by a reversible electrochromic behavior. Their band gap values (E-g) were elucidated utilizing spectroelectrochemical data and it was found that polymers obtained from 2,7-substituted carbazole derivatives have slightly lower band gap values. Furthermore, scanning electron micrographs were used for morphological examinations. (C) 2015 Elsevier B.V. All rights reserved.