Novel fluorescent 2‐(2‐aminofluorophenyl)benzoxazoles: Syntheses and photophysical properties

Abstract

Abstract2‐(2‐Amino‐3,4,5,6‐tetrafluorophenyl)benzoxazole (2) absorbs in long wavelength band (λabsmax = 346 nm in methanol) and in the normal wavelength band (λabsmax = 285.5 nm), and emits blue fluorescence. The emission intensity is highly affected by the solvent polarity and is large in a polar solvent such as methanol. 2‐(2‐Pentafluorobenzamido‐3,4,5,6‐ tetrafluorophenyl)benzoxazole (5) emits green fluorescence along with the short wavelength emission around 380 nm and their relative intensity depends on the solvent polarity. Green fluorescence is enhanced in nonpolar solvents such as chloroform and toluene, resulting in the considerably large Stokes shift.