Synthesis, crystal structures and urease inhibition of copper(II), manganese(III) and nickel(II) complexes derived from 2-bromo- N′ -(2-hydroxy-4-methoxybenzylidene) benzohydrazide

Hydrazones have interesting biological activities. In this work, three new copper(II), manganese(III) and nickel(II) complexes, [Cu2(HL)2(OH2)2](NO3)2·2H2O (1), [MnLL′(CH3OH)] (2) and [Ni2(HL)2(OH2)2(DMF)2](ClO4)2 (3), where L is the dianionic form of 2-bromo-N′-(2-hydroxy-4-methoxybenzylidene)benzohydrazide (H2L), HL is the deprotonated form of H2L, and L′ is the deprotonated form of 4-methoxysalicylaldehyde, were prepared and characterized by physico-chemical methods. Molecular structures of the complexes have been determined by single crystal X-ray crystallography. In complexes 1 and 3, the hydrazone ligands coordinated to the metal atoms through phenolate oxygen, imino nitrogen and carbonyl oxygen atoms. In complex 2, the hydrazone ligands coordinated to the manganese atom through phenolate oxygen, imino nitrogen and enolate oxygen atoms. The Cu atoms in complex 1 are in square pyramidal coordination, and the Mn and Ni atoms in complexes 2 and 3 are in octahedral coordination. Crystals of the complexes are stabilized by hydrogen bonds. The complexes were tested for their urease inhibitory activities. Complex 1 has the most activity on Jack bean urease (IC50 = 1.4 ± 0.2 μmol L−1).