An NBD-based sensitive and selective fluorescent sensor for copper(II) ion

A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) derived fluorescent probe (1) exhibiting high selectivity for Cu(2+) detection, produced significant fluorescence quenching in the presence of Cu(2+) ion, while the metal ions Ca(2+), Cd(2+), Co(2+), Fe(2+), Hg(2+), Mg(2+), Mn(2+), Ni(2+) and Zn(2+) produced only minor changes in fluorescence. The apparent association constant (K (a)) for Cu(2+) binding in chemosensor 1 was found to be 1.22 × 10(3) M(-1). The maximum fluorescence quenching activity caused by Cu(2+) binding to 1 was observed over the pH range 6-10.