Determination of the binding constants of propeller-like metal complexes of picolinaldehyde-2-pyridylhydrazone

Abstract

Herein, we determined the binding constants for transition metal complexes of Cu2+, Co2+, Fe2+, Ni2+, and Zn2+ ions formed with the ligand picolinaldehyde-2-pyridylhydrazone (PapyH) using the Benesi-Hildebrand method. Stoichiometry 2:1 (ligand: metal) was previously determined by the Job’s method and confirmed by single-crystal X-ray diffraction finding a propeller-like structure of the [Fe(Papy)2] compound. PapyH and the metal complexes were characterized by 1H NMR and UV-Vis spectroscopy, respectively. The Cu2+ complex exhibited the highest stability constant, which was confirmed by competitive reaction of different metal ions with the ligand PapyH.