Photoluminescent and Liquid‐Crystalline Properties of Donor–Acceptor‐Type 2,5‐Diarylthiazoles |
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Authors: | Junichi Shikuma Atsunori Mori Prof?Dr Kentaro Masui Ryuichi Matsuura Akitoshi Sekiguchi Haruka Ikegami Masuki Kawamoto Dr Tomiki Ikeda Prof?Dr |
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Institution: | 1. Department of Chemical Science and Engineering, Kobe University, 1‐1 Rokkodai, Nada, Kobe 657‐8501, Japan, Fax: (+81)78‐803‐6181;2. Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori‐ku, Yokohama 226‐8503, Japan |
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Abstract: | The synthesis of donor–acceptor‐type 2,5‐diarylthiazoles that bear electron‐donating N,N‐dialkylamine and electron‐withdrawing cyano groups at the 2‐ and 5‐position, respectively, were carried out with transition‐metal‐catalyzed C? H arylation reactions developed by us. The compounds were synthesized by the C? H arylation of unsubstituted thiazole at the 2‐position with a palladium/copper catalyst in the presence of tetrabutylammonium fluoride (TBAF) as an activator. Further C? H arylation of the 2‐arylated thiazole at the 5‐position was carried out by the palladium‐catalyzed reaction in the presence of silver(I) fluoride to afford the donor–acceptor‐type 2,5‐diarylthiazoles with N,N‐dialkylamine groups of different chain lengths. The UV/Vis absorption, photoluminescence, and electrochemical behavior were similar regardless of chain length, whereas liquid‐crystalline behavior and thermal characteristics were found to be dependent on the alkyl‐chain length. The compounds with N,N‐diethylamine or N‐butyl‐N‐methyl groups showed a stable liquid‐crystalline phase over a wide temperature range as well as higher stability to thermal decomposition. |
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Keywords: | arylation diarylthiazoles donor– acceptor systems liquid crystals photoluminescence |
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