Anion induced synthesis, crystal structures and urease inhibition of copper(II) complexes derived from N'-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-methylbenzohydrazide.

Aroylhydrazones have attracted considerable attention owing to their diverse biological properties and strong coordination ability toward metal ions. In the present study, two novel copper(II) complexes, [CuL(MeOH)]NO3·MeOH (1) and [CuBrL(MeOH)]·MeOH (2), derived from the aroylhydrazone ligand N'-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-methylbenzohydrazide (HL), were successfully synthesized and comprehensively characterized using various physicochemical techniques. Single-crystal X-ray diffraction analyses revealed that the ligand coordinates to the copper(II) center in its deprotonated form (L⁻). Complex 1 exhibits a square planar geometry, and complex 2 exhibits a distorted square-pyramidal geometry around the Cu(II) ions. In complex 1, the coordination polyhedron is formed by the three donor atoms of the aroylhydrazone ligand and one methanol oxygen. In complex 2, the basal plane is defined by the three donor atoms of the aroylhydrazone ligand and one methanol oxygen, and the axial position is occupied by a bromide ligand. In addition, one methanol molecule is present as a solvent of crystallization in each complex. The supramolecular architectures of the complexes are further reinforced through intermolecular hydrogen-bonding interactions. Biological evaluation demonstrated that both copper(II) complexes possess remarkable inhibitory activity against Jack bean urease, with IC50 values of 0.5 and 1.1 μmol L⁻1 for complexes 1 and 2, respectively, indicating their potential as potent urease inhibitors.