Synthesis and structural characterization of dinuclear Zinc(II) and Europium(III) complexes based on a bis-hydrazone ligand

Abstract

A C2-symmetrical N,O-Schiff base ligand containing two hydrazone units has been synthesized and structurally characterized. The solid state structure as determined by single-crystal X-ray diffraction analysis reveals the presence of both intramolecular and intermolecular hydrogen bonds which lead to the formation of a C1-symmetrical conformation as well as a novel one-dimensional (1-D) helical hydrogen-bonded network. The reactions of this bis-hydrazone ligand with zinc(II) and europium (III) salts under appropriate conditions resulted in dinuclear mono-ligand zinc and tri-ligand europium complexes, respectively. The complexes were characterized by NMR spectroscopies, mass spectrometry and elemental analysis. The zinc complex has been further structurally determined by X-ray crystallography. In its solid state structure, the ligand is doubly deprotonated incorporating two zinc(II) cores that are bridged with both phenol-O group and acetate counterions. The solution electronic absorption and emission properties were characterized for both the ligand and zinc complex.