Synthesis, Crystal Structure and Fluorimetric Study of 2-phenylphthalazin-1(2H)-one: a Highly Selective Florescent Chemosensor for Detection of Fe and Fe Metal Ions.

A ligand, 2-phenylphthalazin-1(2H)-one (K), was synthesized by refluxing 2-formylbenzoic acid with phenyl hydrazine in presence of ethanol. FTIR, elemental analysis and single crystal XRD techniques were used to elucidate the structure. Fluorimetric turn-off response was recorded when solution of ligand (K) in DMF was treated with aqueous solution of Fe and Fe metal ions. No specific changes were observed on addition of other metal ions (Pb, Cd, Mn, Zn, Ba, Ni, Al, Ag, Co, Ca, Cu, Mg, Cr). Limit of Detection (LOD) was calculated for Fe and Feas 2.4 µM and 2.5µM respectively, which is quite below to the recommended value 5.4 µM of the Environment Protection Agency of USA. Association constants for Fe and Fe metal ions were determined as 6 × 10 M and 3.6 × 10 M respectively. Benesi-Hildebrand plot confirmed 1:1 binding ratio between metal ions and ligand.