Synthesis of new fluorescent ligands, investigation of ion sensor properties and spectroflorimetric determination of Hg (II)

In this work, the new fluorescent Schiff bases carrying dipicolylamine groups were synthesized by the reaction of the corresponding amine compound and 1-naphthaldehyde, 9-anthraldehyde, phenanthrene-9-carboxaldehyde and 1-pyrenecarboxaldehyde. The influences of Cu2+, Co2+, Hg2+, Al3+, Cr3+, Fe3+, Pb2+, Ni2+, Cd2+, Zn2+, Mn2+, Ag+, Ba2+, Ca2+, Mg2+, I-, Br-, Cl-, F-, CH3COO-, NO3-, CN-, SO42-, HSO4-, CO32-, HCO3-, PO43-, P2O74- on the spectroscopic properties of the ligands were investigated by means of emission spectrometry in ethanol-water (1:1). The spectrofluorimetric measurements disclosed the complexation stoichiometry and the complex stability constants of the ligands with Cd2+, Zn2+, Cu2+ and Hg2+ ions. The Schiff base derived from phenanthrene-9-carboxaldehyde showed sensitivity for Hg2+ with detection range from 40.0 µg/L to 150.00 µg/L. The compound was used as analytical ligand for the simple and fast determination of Hg2+ ion in tap water samples. A modified standard addition method was used to eliminate the matrix effect. Detection and quantification limits were 13.3 µg/ L and 40.0 µg/L, respectively.