Synthesis, X-Ray Crystal Structures and Urease Inhibitory Activity of 3,5-Dihydroxy-N’-(pyridin-2-ylmethylene)benzohydrazide and its Copper(II) and Nickel(II) Complexes

Abstract

Hydrazone compounds have interesting biological activities. In this work, a new hydrazone compound 3,5-dihydroxy-N’-(pyridin-2-ylmethylene)benzohydrazide (HL) was synthesized and characterized by IR, UV-Vis, ¹H and ¹³C NMR spectroscopy. The compound reacts with copper chloride and nickel acetate, respectively, to afford metal complexes [CuCl₂(HL)]∙CH₃OH (1∙CH₃OH) and [NiL₂]∙2CH₃OH∙2H₂O (2∙2CH₃OH∙2H₂O). The complexes were characterized by elemental analysis, and IR and UV-Vis spectroscopy. Structures of HL and the complexes were further confirmed by single crystal X-ray determination. The hydrazone ligand in complex 1 adopts neutral form and coordinates to Cu ion through pyridine nitrogen, imino nitrogen and carbonyl oxygen atoms. The hydrazone ligands in complex 2 adopt monoanionic form and coordinate to Ni ion through pyridine nitrogen, imino nitrogen and enolate oxygen atoms. The Cu atom in complex 1 is in square pyramidal coordination, and the Ni atom in complex 2 is in octahedral coordination. The compounds were tested for their urease inhibitory activities. Complex 1 has remarkable activity on Jack bean urease (IC₅₀ = 0.5 ± 0.1 μmol L^–1).