Solvent‐ and concentration‐sensitive fluorescence of 2‐(3,4,5,6‐tetrafluoro‐2‐hydroxyphenyl)benzoxazole

2‐(3,4,5,6‐Tetrafluoro‐2‐hydroxyphenyl)benzoxazole (2) emits the long wavelength fluorescence around 500 nm in nonpolar solvent viathe 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, 2emits 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.