Synthesis, characterization, theoretical and molecular docking studies of mixed-ligand complexes of Cu(II), Ni(II), Co(II), Mn(II), Cr(III), UO2(II) and Cd(II)

Abstract

A novel bis-bidentate azo dye ligand, formed by the diazotized reaction of 1,4-diaminobenzene and 8-hydroxyquinoline in 1:2 M ratio resulted the formation of 5,5'-{(1E, 1E′)-1,4-phenylenebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H2L1) as primary ligand and its Cu(II), Ni(II), Co(II), Mn(II), Cr(III), UO2(II) and Cd(II) complexes. Incorporating of 8-hydroxyquinoline (HL2) as co-ligand with the formed mixed-ligand complexes were synthesized and characterized using elemental analysis, FT IR, 1 H NMR, UV–visible and mass spectroscopy as well as molar conductance, magnetic measurements, solid reflectance, thermal analysis, electron spin resonance and X-ray diffraction. From elemental and spectral data, the formulae [M2(L1)(L2)2(OH2)4] (where M = Cu(II) (1), Co(II) (2), Ni(II) (3), Mn(II) (4), UO2(II) (6), Cd(II) (7)) and [Cr2(L1)(L2)2(H2O)2(Cl)2] (5) for the metal complexes have been proposed. The geometric structures of the mixed-ligand complexes were found to be octahedral and the XRD patterns showed the polycrystalline natures. The bond lengths, bond angles, the highest occupied molecular orbital energy, the lowest unoccupied molecular orbital energy and quantum chemical parameters were calculated to confirm the geometry of the mixed-ligand complexes (1–5 & 7). The molecular docking was used to predict the efficiency of binding between mixed-ligand complexes (1–7) with receptor of the prostate cancer (PDB code: 2q7k). The theoretical study was used to calculate the HOMO–LUMO energies gap (ΔE) for mixed-ligand complexes (1–5 & 7).