One-Step Synthesis of Low Molecular Weight Poly(p-phenyleneethynylenevinylene)s via Polyaddition of Aromatic Diynes by Catalysis of the [Ru(p-cymene)Cl2]2/AcOH System

π-Conjugated low mol. wt. polymers characterized by regio- and stereoregular alternation of phenylene and (E)-1-en-3-yne moieties were synthesized by polyaddn. of 1,4-diethynylbenzene or of 2,5-diethynyl-1,4-alkoxybenzene monomers, employing the com. available di-μ-chlorobis[(p-cymene)chlororuthenium(II)] complex as the metal catalyst source, under homogeneous, atom-economical, amine- and phosphine-free conditions. Bulk materials of poly(p-phenyleneethynylenevinylene) derivs. are obtained with yields larger than 80%, from which polymers readily sol. in chlorinated solvents and in THF are extd. in 60-75% yields. The polymers with av. d.p. in the range nAV = 4-8 display optical properties in soln. similar to those of the higher mol. wts. analogs