Synthesis and electrochromic properties of polyamides having pendent carbazole groups

Two series of electroactive polyamides (5a–d and 5′a–d) with pendent carbazole groups were synthesized from N-(4-(3,6-di-tert-butylcarbazol-9-yl)phenyl)-3,5-diaminobenzamide (3) and N-(4-(carbazol-9-yl)phenyl)-3,5-diaminobenzamide (3′), respectively, with four dicarboxylic acids via the phosphorylation polyamidation technique. These polyamides were readily soluble in many organic solvents and could afford strong and flexible films via solution casting. They showed useful levels of thermal stability, with Tg in the range of 271–322 °C. The dilute solutions of these polyamides showed a blue photoluminescence with emission maxima around 375–438 nm. They showed well-defined and reversible redox couples upon electrochemical oxidation, together with a strong color change from a colorless neutral form to blue or green oxidized forms. The 5 series polyamides exhibited better redox-stability and electrochromic performance as compared to the corresponding analogs (the 5′ series) without tert-butyl substituents on the active sites of the carbazole unit.