Novel soluble and fluorescent poly(arylene ether)s containing p-quaterphenyl, 2,5-bis(4-phenylphenyl)oxadiazole, or 2,5-bis(4-phenylphenyl)triazole groups

Three novel conjugated biphenols 3, 4, and 8 were synthesized by the Pd(OAc)₂-catalyzed regioselective carbon-carbon coupling reaction of 2,6-di-tert-butylphenol or 2-phenylphenol with aryl halides. Although poly(arylene ether)s derived from biphenol 3 and arylene difiuorides have low solubility in organic solvents, using 4,4′-(9-fluorenylidene)diphenol or 4,4′-(hexafluoroisopropylidene)diphenol as a comonomer gave soluble poly(arylene ether)s 6a-c. High molecular weight poly(arylene ether)s 7a′-c′ were also prepared from biphenol 4. The biscarbamate-masked monomers 5 and 9 improved the polymerization to give higher molecular weight polymers 7a-e and 10a-e in higher yields. Polymers 7 and 10 possess better film-forming capabilities and are still soluble in organic solvents. Polymers 6, 7, and 10 are all thermally stable with 5% weight loss temperatures higher than 500 °C under nitrogen. The polymers show strong blue light emission ranging from 387 to 478 nm in solution, depending on the conjugated structure.