Electrosynthesis and properties of poly(3,4-ethylenedioxythiophene) films functionalized with titanocene dichloride complex

Synthesis of a titanocene dichloride derivative functionalized with 3,4-etylenedioxythiophene group, Tc1EDOT (Cl₂TiCpC₅H₄(CH₂) (3,4-ethylenedioxythiophene)) has been described. Redox behavior of the monomer in tetrahydrofuran (THF), dichloromethane (DCM) and acetonitrile (AN) at different scan rates has been discussed in terms of different ability of these solvents to coordination with the reduced titanocene (Tc) complex and the solvation of Cl⁻ anions. Electrooxidation of Tc1EDOT to get a conducting polymer film with immobilized titanocene dichloride centers and electrochemical properties of its polymer matrix in background acetonitrile solution have been compared with those of non-substituted PEDOT and PEDOT-methanol derivative (PEDOTMet), to elucidate the effect of substituents both on polymerization and redox potentials of the matrix. STM and AFM images of p(Tc1EDOT) films obtained with potentiodynamic and potentiostatic regimes are compared to illustrate that the films deposited at constant potential are better ordered and more compact than those obtained by cyclic voltammetry. A comparison of the cyclic voltammograms of p(Tc1EDOT) and poly(titanocene-propyl-pyrrole) (p(Tc3Py)) films in 0.1 TBAPF₆ in THF has shown that the electroactivity of the polymer matrix of p(Tc1EDOT) is extended to more negative potentials in comparison to that of p(Tc3Py). This results in the anodic shift of redox potential of Tc centers immobilized in p(Tc1EDOT) film with respect to that of the centers fixed in p(Tc3Py).