Novel coumarin fluorescent dyes: Synthesis, structural characterization and recognition behavior towards Cu(II) and Ni(II)

A series of novel coumarin dyes (3–12) were designed and synthesized. The structures of the dyes were characterized by IR, 1H NMR, 13C NMR, 19F NMR, MS and single crystal X-ray diffraction. 3-(2-Benzoylhydrazonotrifluoroethyl)-7-(N,N-diethylamino)coumarin (11) could recognize Cu2+ and Ni2+ selectively in aqueous solution. Upon addition of Cu2+ or Ni2+ to 11 a blue shift or a bathochromatic shift of the absorption band was observed while the emission band blue-shifted with decrease in the fluorescence intensity. Upon addition of Cu2+ the color of the solution of 11 changed from orange to red. The results showed that 11 could be used as an optical chemosensor of Cu2+ and Ni2+.

► Novel coumarin dyes were synthesized and characterized.
► A coumarin dye (11) could recognize Cu2+ and Ni2+ selectively in aqueous solution.
► Upon addition of Cu2+ the color of the coumarin solution changed from orange to red.