ELECTRICALLY CONDUCTING POLYMERS CONTAINING SUBSTITUTED PHENYLENE AND HETEROCYCLE REPEAT UNITS

A series of polymers containing alternating biheterocycle and p-phenylene repeat units has been synthesized and studied. When the heterocyclic unit is thiophene, the materials demonstrate electrochemical properties similar to those found for polythiophenes and retain the synthetic flexibility for substitution found in phenylene compounds. The monomers were substituted at the 2- and 5-positions of the phenylene ring with methyl, methoxy, heptoxy, dodecyloxy and hexyl groups. The electronic properties were found to depend on both the electron donating ability and the steric effects of the substituents. PRDDO and ab initio calculations were carried out to correlate the molecular structure with the observed electronic properties. Optoelectrochemical and solution doping results revealed the presence of bipolaron species in the oxidized state and the optical band gap was compared with extended Huckel calculations. The monomers and polymers were characterized using a variety of FT-NMR and FT-IR techniques.