Detection of Fe2+ in acetonitrile/water mixture by new 8-hydroxyquinolin based sensor through metal displacement mechanism

Abstract

Abstract 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 Cu 2+ and Ni 2+ ions were fully quenched the fluorescence intensity of 2 . But, a significant enhancement in the fluorescent intensity was observed when the bound Ni 2+ and Cu 2+ ions in the 2 ─Ni and 2 ─Cu complexes were displaced by Cr 3+ and Fe +2 ions, respectively. While 2 ─Ni exhibited low sensitivity toward Cr 3+ 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 Fe 2+ in aqueous medium.