Synthesis and characterization of nonfluorescent poly(p-aryleneethynylene)s by alkyne metathesis

Alkyne metathesis of mixtures of 2,5-didodecyl-1,4-dipropynylbenzene and {1 ,3-bis[2',5'-didodecyl-4'-propynyl(phenylethynyl)]-2,4-bis(trimethylsilyl)c yclobutadiene}cyclopentadienylcobalt in the presence of Mo(CO)(6) and 4-tri fluoromethylphenol at 150 degreesC furnishes a series of organometallic PPE copolymers in which CpCo-ligated (cyclobutadienylene)ethynylene units are interspersed into the phenyleneethynylene chains. The copolymers were inves tigated by UV-vis and fluorescence spectroscopy. Both techniques showed a d ramatic influence of the presence of even small amounts of organometallic m odules on the photophysical properties of the polymers.