Solvent‐ and concentration‐sensitive fluorescence of 2‐(3,4,5,6‐tetrafluoro‐2‐hydroxyphenyl)benzoxazole |
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Authors: | Kiyoshi Tanaka Makoto Deguchi Satoru Yamaguchi Kouji Yamada Satoru Iwata |
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Abstract: | 2‐(3,4,5,6‐Tetrafluoro‐2‐hydroxyphenyl)benzoxazole ( 2 ) emits the long wavelength fluorescence around 500 nm in nonpolar solvent via the intramolecular proton transfer process in the excited state of 2 (enol‐form) and also emits the intermediate wavelength fluorescence around 440 nm in polar solvent, which is assumed to originate from the excited state of 2 (anion). The ease of formation of 2 (anion), compared to 2‐(2‐hydroxyphenyl)benzoxazole ( 1 ), is explained by the strongly inductive fluorine atoms. In a solvent with the intermediate polarity, 2 emits both fluorescences and their relative intensity is dependent on the concentration of 2 , which is supposed to be caused by the high sensitivity of the intermediate wavelength emission to the concentration quenching. |
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