Electrochemical properties of a new star-shaped pyrrole monomer and its electrochromic applications

A new monomer, 2,4,6-tris(4-(1H-pyrroI-1-yl) phenoxy)-1,3,5-triazine (Tria-Py) was synthesized via the reaction,of 4-(1H-pyrrol-1-yl)phenol with 2,4,6-trichloro-1,3, 5-triazine. It was electrochemically polymerized in a dichloromethane/acetonitrile solvent mixture. The polymer P(Tria-Py) was characterized via CV, FTIR, SEM and uv-vis spectroscopy. Spectroelectrochemical analysis revealed electronic transitions at 346, 508 and 665, nm, revealing pi to pi* transitions, and polaron and bipolaton band formations respectively, We also made a dual-type, complementary-colored electrochromic device using P(Tria-Py)/poly(3,4-ethylenedioxythiophene) (PEDOT) in a sandwich configuration. The device switches between dark blue and red colors with a switching time of 2.2 s and an optical contrast (% Delta T) of 25%.