STRUCTURE OF POLYINDOLES FROM ANODIC COUPLING OF INDOLES - AN ELECTROCHEMICAL APPROACH

The structure of polyindoles from anodic coupling of indole, 5-carboxy indole, 5-cyanoindole, and biindoles were investigated by cyclic volta mmetry (CV), FTIR and UV-vis spectroscopies and in situ conductivity. The presence of the NH signal in the IR spectrum of the neutral polyme rs indicates that the polyindoles are coupled at the 2 and 3 positions . The shape and the pH dependence of the CV response, the potential wi ndow of conductivity, the disappearance of the NH band upon oxidation and the pH-dependent electrochromism, analogous with those of polyanil ine, are due to a regular alternance of 2,2 and 3,3 couplings. Polyind oles of different chain length are produced from anodic coupling of 2, 2'- and 3,3'biindoles.