Synthesis, structures and urease inhibition studies of Schiff base metal complexes derived from 3,5-dibromosalicylaldehyde

Eleven mononuclear copper(II), nickel(II), zinc(II) and cobalt(II) complexes of Schiff base ligands derived from 3,5-dibromosalicylaldehyde/3,5-dichlorosalicylaldehyde were synthesized and determined by single crystal X-ray analysis. The crystal structures of complexes 1, 2, 4, 5, 6, 8 and 11 present the square-planar coordination geometry at the metal center and complexes 7, 9 and 10 show the distorted tetrahedral geometry. While one copper center in 3 has a square-planar geometry, the other copper is slightly distorted square-planar. The inhibitory activities of all the obtained complexes were tested in vitro against jack bean urease. It was found that Schiff base copper(II) complexes 1, 3, 5, 8 and 11 showed strong urease inhibitory activities (IC50 = 1.51–3.52 μM) compared with acetohydroxamic acid (IC50 = 62.52 μM), which was a positive reference. Their structure–activity relationships were further discussed.

We describe the synthesis, molecular modeling, and biological evaluation of eleven mononuclear copper(II), nickel(II), zinc(II) and cobalt(II) complexes. The results demonstrate that Schiff base copper(II) complexes possess good inhibitory activities and well binding affinities by forming hydrophobic interactions with jack bean urease.Figure optionsDownload as PowerPoint slideHighlights
► Eleven mononuclear complexes were synthesized and determined.
► The inhibitory activities of the complexes were evaluated against jack bean urease.
► The preliminary docking study and “structure–activity” relationship were discussed.