Synthesis, electrochemical and fluorescence properties of three new dithienylpyrroles bearing aromatic amine units

Three new kinds of dithienylpyrroles derivatives bearing aromatic amine units were successfully synthesized by the Knorr–Paal condensation. The corresponding polymer films were also successfully prepared on ITO working electrode via electropolymerization in a low concentration containing 0.2 mM monomer in 0.01 M tetrabutylammonium perchlorate/dichloromethane solution. The electrochemical, surface morphology, thermal stability, spectroelectrochemistry properties and electrochromic behavior of the three polymer films were further investigated by cyclic voltammetry, scanning electron microscopy, thermogravimetric analysis, UV–vis absorption. The results demonstrated that the three electroactive polymer films possessed low optical band gap (Eg < 2.3 eV), smooth film surface, thermal stability (up to nearly 200 °C). All of the three polymer films presented a stable and well-defined reversible redox process as well as multicolor electrochromic change mainly from yellow green (in the reduced state) to grey green (in the neutral state) and then to blue (in the oxidized state).

► Three new kinds of dithienylpyrroles derivatives were successfully synthesized.
► Their polymer films were successfully synthesized via electropolymerization.
► They possessed low optical band gap, smooth surface, thermal stability.
► They presented a good reversible redox process and multicolor electrochromic change.