Intensely fluorescent azobenzenes: synthesis, crystal structures, effects of substituents, and application to fluorescent vital stain.
Intensely fluorescent azobenzenes: synthesis, crystal structures, effects of substituents, and application to fluorescent vital stain.
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DOI：
10.1002/chem.201000258
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发表时间：
2010-05
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影响因子：
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通讯作者：
J. Yoshino;A. Furuta;Tetsuya Kambe;Hiroaki Itoi;N. Kano;T. Kawashima;Yuzuru Ito;M. Asashima
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文献类型：
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作者：
J. Yoshino;A. Furuta;Tetsuya Kambe;Hiroaki Itoi;N. Kano;T. Kawashima;Yuzuru Ito;M. Asashima
合成了4 ′-位带有氢、甲氧基、二甲氨基、三氟甲基、氟、正丁基和叔丁基二甲基硅氧基或4-位带有甲氧基和溴基的2-[双（五氟苯基）硼基]偶氮苯。2-硼基-4-溴偶氮苯衍生物的4-溴基团通过钯催化反应转化为苯基和二苯基氨基。利用紫外-可见光谱（UV/维斯）和荧光光谱研究了其吸收和荧光性质。2-硼基偶氮苯发射强烈的绿色、黄色和橙子荧光，与通常的偶氮苯荧光形成鲜明对比。4 '-甲硅烷氧基衍生物显示出最高的荧光量子产率（0.90）中报道的偶氮苯的日期。通过研究取代基对弛豫过程的影响以及DFT和TD-DFT计算，阐明了取代基与荧光性质之间的相关性。发现在4 '-位的给电子基团对于强发射是重要的。应用荧光偶氮苯作为活体组织的可视化荧光活体染料也进行了研究，通过显微注射到非洲爪蟾胚胎，表明这些化合物对胚胎无毒。
2-[Bis(pentafluorophenyl)boryl]azobenzenes bearing hydrogen, methoxy, dimethylamino, trifluoromethyl, fluoro, n-butyl, and tert-butyldimethylsiloxy groups at the 4'-position or methoxy and bromo groups at the 4-position have been synthesized. The 4-bromo group of the 2-boryl-4-bromoazobenzene derivative was converted to phenyl and diphenylamino groups by palladium-catalyzed reactions. The absorption and fluorescence properties have been investigated using UV/Vis and fluorescence spectroscopy. The 2-borylazobenzenes emitted an intense green, yellow, and orange fluorescence, in marked contrast to the usual azobenzene fluorescence. The 4'-siloxy derivative showed the highest fluorescence quantum yield (0.90) among those reported for azobenzenes to date. The correlation between the substituent and the fluorescence properties was elucidated by studying the effect of the substituent on the relaxation process and from DFT and TD-DFT calculations. An electron-donating group at the 4'-position was found to be important for an intense emission. Application of fluorescent azobenzenes as a fluorescent vital stain for the visualization of living tissues was also investigated by microinjection into Xenopus embryos, suggesting these compounds are nontoxic towards embryos.