Synthesis, structures and urease inhibition studies of copper(II) and nickel(II) complexes with bidentate N,O-donor Schiff base ligands

Abstract

Five mononuclear copper(II) and nickel(II) complexes of Schiff base ligands derived from 4-hydroxyphenethylamine and 2-phenylethylamine were synthesized and determined by single crystal X-ray analysis. The crystal structures of these complexes presented the square planar coordination geometry at the metal center. The inhibitory activity of all the obtained complexes was tested in vitro against jack bean urease. It was found that Schiff base copper(II) complexes, namely [Cu(C15H13BrNO2)2]·2(C6H7N) (1), [Cu(C15H12Br2NO2)2]·2(DMF) (2), Cu(C19H16NO2)2 (3) and Cu(C19H16NO)2 (5), showed strong inhibitory activity against jack bean urease (IC50=1.45–3.59μM), while Schiff base nickel(II) complex, [Ni(C19H16NO2)2]·2(DMF) (4), exhibited weak inhibitory activity (IC50>50μM). Their structure–activity relationships were further discussed.