Synthesis and properties of soluble, strongly fluorescent poly(m-phenylene)s with pendant stilbene-based chromophores

The nickel-catalyzed dehalogenative coupling of substituted m-dichlorobenzenes afforded a mew series of poly(m-phenylene)s with pendant 2,6-bisstilbenyl-N-alkylpyridinium tetrafluoroborate groups. Characterization of polymers was accomplished by viscosimetry, GPC, FT-IR, NMR, X-ray, differential scanning calorimetry, thermomechanical analysis, UV-vis, and luminescence spectroscopy. The polymers were amorphous and showed an excellent solubility being readily soluble at room temperature in THF, chloroform, and chlorobenzene. Their T-g values ranged from 96 to 148 degreesC. The polymers with pendant stilbene-based chromophores were strongly fluorescent both in solution and in solid state. Their photoluminescence (PL) spectra showed maxima at 391-410 nm and 445-532 nm in solution and in thin film, respectively. The structure of the alkyl attached to the pyridinium nitrogen influenced remarkably the PL quantum yield of polymers. The most efficient fluorescent polymers obtained were those bearing long chain aliphatic group on this nitrogen. Their PL quantum yield in THF solution was up to 0.65. [GRAPHICS] ]