A 8-hydroxyquinoline-based (8-HQ) fluorescent ligand (2) was designed and synthesized by condensation of pyridine-2-carboxaldehide with 2-(quinolin-8-yloxy)acetohydrazide (1). Fluorometric titrations with various metal ions in 1:1 M ratio showed that Cu2+ and Ni2+ ions were fully quenched the fluorescence intensity of 2. But, a significant enhancement in the fluorescent intensity was observed when the bound Ni2+ and Cu2+ ions in the 2-Ni and 2-Cu complexes were displaced by Cr3+ and Fe+2 ions, respectively. While 2-Ni exhibited low sensitivity toward Cr3+ ion, the fluorescent titration measurements showed that 2-Cu could be a good "on-off-on" selective and sensitive sensor (S) candidate for determination of Fe2+ in aqueous medium. (C) 2016 Elsevier B.V. All rights reserved.