Synthesis of polyphenylenes through bergman cyclization of enediynes with long chain alkyl groups
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Several new enediynes with long chain alkyl groups were synthesized through Sonogashira coupling reactions between long chain alkynes and (Z)-1,2-dichloroethene. These enediynes (1) were then subjected to thermal Bergman cyclization in a refluxing diphenyl ether bath under vacuum to obtain conjugated polyphenylenes with the weight-average molecular weights up to 4.9 × 103 g·mol−1. The occurrence of Bergman cyclization was confirmed by 1H-NMR, 13C-NMR, and IR spectroscopic analysis. These polyphenylenes are fully soluble in common organic solvents and exhibit good thermal stability. The optical properties of the polyphenylenes were investigated by UV-Vis absorption and photoluminescence (PL) spectroscopies. A blue emission was observed for all these polyphenylenes.
KeywordsEnediyne Bergman cyclization Polyphenylene
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