Selective aqueous fluorescent probes for metal ions based on benzoyl hydrazone derivatives

Abstract

Three novel fluorescent compounds were synthesized and employed as fluorescent probes for detecting different metal ions selectively. The naphthol-based probe (I) exhibited weak fluorescence in water, which was enhanced in the presence of Al³⁺ ions due to the complexation between I and Al³⁺. In addition, the coumarin-based probe (II) and quinolone-based probe (III) could selectively detect Cu²⁺ ions and Zn²⁺ ions, respectively. Unlike the changes in the fluorescence spectra of I and III upon Al³⁺ ion and Zn²⁺ ion addition, the fluorescence intensity of II decreased dramatically after Cu²⁺ ions were added into the aqueous solution. This is due to the fact that different mechanisms occurred in the recognition process for metal ions. Colorimetric monitoring of these processes was also feasible.