Synthesis of π-Conjugated Polymers by Organometallic Polycondensation

Organometallic polycondensations give various pi-conjugated polymers. For example, nickel complex-promoted dehalogenative polycondensation of dihaloaromatic compounds and dihalogenataed heterocyles, X-Ar-X (Ar = aromatic unit or heterocyclic unit), affords poly(arylene)s and poly(heterocycles), (Ar)(n), such as poly(p-phenylene), poly-(thiophene-2,5-diyl), poly(3-alkylthiophene-2,5-diyl), and poly(pyridine-2,5-diyl). Pd-catalyzed polycondensation gives poly(aryleneethynylene) type polymers and alternating copolymers of Ar and Ar'. These polymers have well defined bonds between the monomeric units, and they are electrochemically active, electrically conductive, and light-emitting. Their well-characterized linear structure brings about unique packing of the polymer molecules in the solid and alignment of the polymer molecules on the surface of substrates. In this paper, we describe synthesis of pi-conjugated polymers by organometallic polycondensations. Basic chemical and physical properties of the synthesized pi-conjugated polymers, as well as ordered structures in the solid and applications for electronic and optical devices of the pi-conjugated polymers, are also described.