A highly selective and instantaneously responsive Schiff base fluorescent sensor for the "turn-off" detection of iron(iii), iron(ii), and copper(ii) ions

A new and tri-responsive fluorescent Schiff base probe (DBAB) has been designed and developed for the recognition of iron(III) ions (Fe3+), iron(II) ions (Fe2+) and copper(II) ions (Cu2+) simultaneously. This sensor displays a favorable selectivity for Fe3+, Fe2+ and Cu2+ ions over a range of other common metal cations in DMF solution, leading to prominent fluorescence on-off. The detection limits were 2.17 x 10(-6) M for Fe3+, 2.06 x 10(-6) M for Fe2+ and 2.48 x 10(-6) M for Cu2+ respectively. This tri-responsive fluorescent probe for Fe3+, Fe2+ and Cu2+ was distinguished by further reduction of the ascorbic acid. The recognition mechanism of DBAB toward Fe3+, Fe2+ and Cu2+ has been investigated in detail by Job plot measurements and H-1 NMR.