New alternating donor-acceptor type conjugated copolymer: Poly[bicarbazolylene-alt-phenylene-bis(cyanovinylene)]. Synthesis and properties

The Knoevenagel condensation has been applied to the synthesis of ([bicarbazolylene]-alt-[phenylenebis(cyanovinylene)]) copolymers. These materials are mostly insoluble in organic solvents but, depending an the reaction conditions a small amount of soluble oligomers could be obtained. The alternation of electron-donor carbazolylene units and electron-withdrawing phenylene-cyanavinylene entities is believed to be partly responsible for the rigidity of the macromolecular chains, so explaining their insolubility. Moreover, this regular alternation of donor-acceptor moieties is thought to be responsible for the lowering of the bandgap of the soluble oligomers and for decreasing the stability of the bicarbazolylium radical-cations of the doped state. Lastly, materials were fairly resistant to thermal degradation, up to 450 degrees C. (C) 1997 Elsevier Science Ltd.