Selective fluorescence sensor for Cu2+ with a novel triazole Schiff-base derivative with coumarin units

Novel triazole Schiff-base derivative 3 bearing a coumarin unit was synthesized by the reaction of 4-formylbenzocoumarin ( 1 ) with 3,5-diphenyl-4-amino-1,2,4-triazole ( 2 ). The structure of the product was characterized by means of IR, MS, 1 H NMR, 13 C NMR, and elemental analysis. The UV-vis absorption and fluorescence emission spectra of compound 3 exhibit blue-shifted absorption and fluorescent enhancement upon chelation to cupric ion. Fluorometric titration revealed a 2:1 ligand to metal ratio in the complex and the binding constant of 4.62×10 6 m -1 .