Electrochemical synthesis and characterization of polyconjugated polyfuran.

Polyconjugated polyfuran (PF) was produced by electroreduction of 2,5-dibromofuran in acetonitrile using Ni(bipy)32+ as catalyst. Polymerization occurs only in the presence of excess Ni(bipy)32+ at potentials in the range -1.7 to -2.0 V versus Ag/Ag+ via binuclear organonickel complex. IR spectroscopy, elemental analysis and mass spectroscopy confirm that PF is constituted by 2,5-linked furan units and indicate a degree of polymerization > 100. Red PF films (?max = 420 nm, Eg = 2.2 eV) are reversibly oxidized at 0.45 V and reduced at -2.5 V. Doping with AsF5 gives PF a conductivity of 10-3 S/cm. Polymers produced by anodic coupling of furan were also investigated for comparison. IR spectroscopy and elemental analysis indicate that they display a lower degree of conjugation due to the concomitant acidcatalyzed polymerization.