The new fluorophores of the 3H-imidazo[4,5-e][2,1]benzoxazoles series were synthesized by the regioselective nitration of 3-alkyl-8-phenyl-3H-imidazo[4,5-e][2,1]benzoxazoles. The latter compounds were obtained from the reaction of 1-alkyl-5-nitro-1Hbenzimidazoles with benzyl cyanide in basic MeOH solution. The structures of synthesized compounds were established using spectral (UV-vis, IR, 1H NMR, 13C NMR, and NOESY) and analytical data. Furthermore, it was found that these fluorophores underwent thermal rearrangement to new 5H-imidazo[4,5-f][2,1,3]benzoxadiazole 3-oxides in AcOH in moderate yields. The fluorescence properties and antibacterial activities of new compounds against Gram-positive and Gram-negative bacterial species were also studied.
3H-imidazo[4,5-e][2,1]benzoxazole 5H-imidazo[4,5-f][2,1,3]benzoxadiazole 3-oxide Emission and absorption spectra Fluorescence NOESY
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