Simple preparation of terthiophene-3′-carboxylic acid and characterization of its polymer

Abstract 5,2′-5′,2″-Terthiophene-3′-carboxylic acid (TTCA), a potentially useful starting material for the synthesis of functionalized polyterthiophenes, can be simply prepared by the treatment of 3′-bromothiophene with CuCN in DMF followed by hydrolysis in KOH-ethoxyethanol. TTCA was polymerized on a glassy carbon electrode in a 0.1 M Et 4 NClO 4 /dichloromethane solution. The polymer film was characterized with cyclic voltammetry, in situ UV–VIS spectroscopy, in situ conductivity, and chronoabsorptometry. In contrast to many other conducting polymers, the conductivity of the resulting polymer increased even in a state of full oxidation. In addition, the resulting polymer film displayed fast electrochromic switching.