Urease inhibition studies of six Ni(II), Co(II) and Cu(II) complexes with two sexidentate N2O4-donor bis-Schiff base ligands: An experimental and DFT computational study

Six novel complexes, [Ni(C 36 H 34 N 2 O 10 )]·2.25CH 3 OH·0.5C 4 H 10 O ( 1 ), [Co(C 36 H 34 N 2 O 10 )] ( 2 ), [Cu(C 36 H 34 N 2 O 10 )]·2CH 3 OH ( 3 ), [Ni(C 36 H 32 N 2 O 8 Cl 2 )]·2CH 3 OH ( 4 ), [Co(C 36 H 32 N 2 O 8 Cl 2 )]·4CH 3 OH ( 5 ) and [Cu(C 36 H 32 N 2 O 8 Cl 2 )]·2CH 3 OH ( 6 ) with two sexidentate N 2 O 4 -donor bis-Schiff base ligands (C 36 H 34 N 2 O 10  = 1,2-bis(2-methoxy-6-formylphenoxy)ethane- l -tyrosine; C 36 H 32 N 2 O 8 Cl 2  = 1,2-bis(2-methoxy-6-formylphenoxy)ethane- l -4-chlorophenylalanine) have been synthesized and structurally characterized. Theoretical calculation of the six complexes was carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-3lG basis set, indicating that the calculation results are in accordance with experimental results. Moreover, the inhibitory activities of complexes 1 – 6 were tested in vitro against jack bean urease . At the same time, molecular docking was investigated to determine the probable binding mode. The experimental values and docking simulation exhibited that complexes 3 and 6 showed strong inhibitory activity (IC 50  = 10.36 ± 1.13, 15.63 ± 3.04 μM) compared with the positive reference acetohydroxamic acid (IC 50  = 26.99 ± 1.43 μM). Their structure-inhibitory activity relationship was further discussed from the perspective of molecular docking and theoretical calculation.