Three Co(II) complexes with a sexidentate N2O4-donor bis-Schiff base ligand: Synthesis, crystal structures, DFT studies, urease inhibition and molecular docking studies

Three new N 2 O 4 -donor bis-Schiff base Co(II) complexes, Co(C 36 H 34 N 2 O 8 )·2CH 3 OH ( 1 ), Co(C 28 H 34 N 2 O 8 S 2 )·H 2 O ( 2 ) and Co(C 40 H 36 N 4 O 8 )·3CH 3 OH ( 3 ) with distorted octahedral six-coordinate Co(II) centers were synthesized and determined by single crystal X-ray analysis. The X-ray crystallography shows that the metal atoms of three complexes are all six-coordinate with two nitrogen atoms from C N groups, two oxygen atoms from ether groups and two carboxylic oxygen atoms in the mono-ligand, forming a distorted octahedral geometry. Theoretical studies of the three complexes were carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-31G basis set. The DFT studies indicate that the calculation is in accordance with the experimental results. Moreover, inhibition of jack bean urease by Co(II) complexes 1–3 have also been investigated. At the same time, a docking analysis using a DOCK program was conducted to determine the probable binding mode by inserting the complexes into the active site of jack bean urease. The experimental values and docking simulation exhibited that the complex 3 showed strong inhibitory activity (IC 50  = 16.43 ± 2.35 μM) and the structure-activity relationships were further discussed.