A multifunctional “off–on” fluorescence probe for Al 3+ , Zn 2+ and La 3+ detection and cellular imaging applications

A simple multifunctional Schiff base fluorescence probe (E)- N ′-(2,4-dihydroxybenzylidene)-2-hydroxybenzohydrazide ( NDH ) was designed and synthesized by the reaction of 2,4-dihydroxybenzaldehyde and salicylhydrazide. NDH acts as a “off–on” logic gate fluorescence probe for Al 3+ , Zn 2+ and La 3+ ions, providing different colors and detection limits of 1.22 μM, 2.47 μM and 2.94 μM, respectively. Moreover, the binding stoichiometry of NDH to Zn 2+ was 2:1, but to other metal ions was 1:1, and was confirmed by Job’ plot, 1 H NMR and ESI–MS. Furthermore, the probe NDH was applied to detect Al 3+ , Zn 2+ and La 3+ ions in real water samples and Hela cells. This work might provide a new evidence that the fluorescent probe with “off–on” logic gate can serve as an economical and efficient strategy for simultaneous sensing multiple metal ions. Graphical abstract A novel, highly sensitive and selective fluorescent probe was developed to trace Al 3+ , Zn 2+ and La 3+ in real water samples and live cells.