Synthesis, crystal structures and urease inhibitory activity of copper(II) complexes with Schiff bases

Two thiocyanate-coordinated Schiff base copper(II) complexes, [CuL1(NCS)] (1) and [Cu2(L1)2(μ1,3-NCS)2]n (2), where L1 and L2 are the deprotonated forms of 4-bromo-2-[(2-propylaminoethylimino)methyl]phenol (HL1) and 2-ethoxy-6-[(2-propylaminoethylimino)methyl]phenol (HL2), respectively, have been prepared and structurally characterized. Single crystal X-ray diffraction indicates that 1 is a mononuclear copper(II) complex, while in 2, the adjacent two complex molecules are linked through two phenolate O atoms, forming a dimer. The dimers in 2 are further weakly linked through end-to-end thiocyanate bridges to form a two-dimensional sheet. The Cu atom in 1 is four-coordinate in a square planar geometry, and that in 2 is six-coordinate in an octahedral geometry. Complex 1 shows strong urease inhibitory activity, while complex 2 shows no activity.