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 ...