Structural, molecular docking computational studies and in-vitro evidence for antibacterial activity of mixed ligand complexes

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(quinoline-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 of the composition, [M2(L1)(L2)2(OH2)4] (M = Cu(II), Co(II), Ni(II), Mn(II), UO2(II), Cd(II) and [Cr2(L1)(L2)2(OH2)2(Cl2)] were synthesized and characterized. H2L1, HL2, and their mixed ligand complexes were screened against two local gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and three local gram-negative bacteria (Klebsiella pneumoniae Escherichia coli and Pseudomonas sp). Antifungal activities were determined against Fusarium oxysporum Aspergillus niger, and Candida albicans. Cr(III), Mn(II) and UO2(II) mixed ligand complexes showed higher activity than H2L1 and HL2; their cytological effects on S. aureus and B. cereus along with the in-silico docking showed that these complexes represent antibacterials targeting FtsZ and DltA proteins; hence, affect cell divisions and gram-positive cell walls. The XRD patterns of the Mn(II) and UO2(II) mixed ligand complexes are polycrystalline natures.