Synthesis, structure, and urease inhibitory activities of three binuclear copper(II) complexes with protocatechuic acid derivative

Three Cu(II) complexes, [CuII2(L1)4(L2)2] (1), [CuII2(L1)4(H2O)2]·HL (2), and [CuII2(L1)3(L3)2]ClO4 (3), with a ligand derived from protocatechuic acid (HL1 = C9H8O4=2,3-dihydrobenzo[b][1,4]dioxine-6-carboxylic acid, L2 = C7H9N=o-toluidine, L3 = C6H16N2=N,N-diethylethylenediamine) were synthesized and characterized by C, H, and N elemental analysis and single-crystal X-ray diffraction, which revealed that the three complexes have similar binuclear structures. Complexes 1 and 3 crystallized in triclinic space group P-1 and 2 in orthorhombic space group P212121. The urease inhibitory activities of the three complexes were tested. All three complexes showed strong inhibitory activity against jack bean urease with an IC50 value of 6.8, 5.5, and 3.5 μM compared with the acetohydroxamic acid (IC50 = 7.5 μM), which was a positive control.