Two similar Schiff-base receptor based quinoline derivate: Highly selective fluorescent probe for Zn(II).

As is known, Zn plays a vital role in a variety of biological processes but excessive exposure of Zn to human beings can cause toxicity, inducing a series of overt poisoning symptoms and neurodegenerative disorders. Thus, we designed and synthesized two quinoline-derived Schiff-bases HL and HL, and investigated the fluorescence emission responses of these two Schiff-bases to various metal ions. A significant enhancement in fluorescence emission band centered at 450 nm was observed in the ethanolic solution of HL with addition of Zn, while remarkably lower fluorescence emission enhancement was obtained in the case of HL in which one methyl group was introduced to the azomethine carbon. In addition, HL showed good selectivity and high sensitivity towards Zn in the existence of other various interfering metal ions, and the reversibility and regeneration of HL were also perfect for extending its applications in environmental and biological systems. Therefore, HL could be identified as a fluorescent probe for sensing Zn environmentally and biologically.