Low-oxidation-potential conducting polymers derived from 3,4-ethylenedioxythiophene and dialkoxybenzenes

Monomers derived from 3,4-ethylenedioxythiophene and phenylenes with branch ed or oligomeric ether dialkoxy substituents were prepared with the Negishi coupling technique. Electrooxidative polymerization led to the correspondi ng dialkoxy-substituted 3,4-ethylenedioxythiophene-phenylene polymers, with extremely low oxidation potentials (E-1/2,E-p = -0.16 to -0.50 V vs Ag/Ag) due to the highly electron-rich nature of these materials. The polymers w ere electrochromic, reversibly switching from red to blue upon oxidation, w ith bandgaps at about 2 eV. The electrochemical behavior of the oligomeric ether-substituted polymer was investigated in the presence of different met al ions. Films of the polymer exhibited electrochemical recognition for sev eral alkali and alkaline-earth cations with selectivity in the order Li+ > Ba2+ > Na+ > Mg2+. Cyclic voltammetry showed a decrease in the oxidation po tential and an improvement in the definition of the voltammetric response, as well as an increase in the overall electroactivity of the polymer films when the concentration of the cations in the medium was increased. These re sults are discussed in terms of the electrostatic interactions between the complexed cation and the redox center, as well as the diffusion of the ioni c species into the polymer matrix. (C) 2001 John Wiley & Sons, Inc.