A new approach to the Schiff base-substituted oligophenols: The electrochromic application of 2-[3-thienylmethylene]aminophenol based co-polythiophenes

Two new copolymers were synthesized by electrochemical polymerization of 2-[3-thienylmethylene]aminophenol (2,3-TMAP) and poly-2-[3-thienylmethylene]aminophenol (P-2,3-TMAP) with thiophene (Th) and the obtained thiophene copolymers were examined as electrochromic materials. Electro copolymerization reactions of the compounds were performed in acetonitrile (AN)/boron trifluoride ethyl etherate (BF3EtE) solvent mixture (9:1, v/v) where LiClO4 utilized as the supporting electrolyte. After electro copolymerization reaction, obtained electrochromic films deposited on ITO glass plates, 2,3-TMAP-co-Th and P-2,3-TMAP-co-Th, were investigated as spectroelectrochemically. The new electrochromic materials derived from Schiff base substituted-phenol/oligophenols are red colored at low potentials and blue colored at high potentials. Electro copolymerization mechanism was identified. Spectroelectrochemical monitoring showed good absorption recovery for P-2,3-TMAP-co-Th, while absorbance decrease was observed for 2,3-TMAP-co-Th during the repeated potential scans. Suitable potential range for operating the device from red to blue was found to be between 0 and +1.4 V. P-2,3-TMAP-co-Th showed 12-13% transmittance changes at applied potentials and the response times were 3.1 and 4.1 s for 476 and 800 nm, respectively. As a result P-2,3-TMAP-co-Th may be good candidate for electrochromic devices and can be thought as a feasible nominee for anodically coloring electrochromic layers in ECDs. (C) 2010 Elsevier B.V. All rights reserved.