New potential Mn(II) mixed ligand complexes: synthesis, structural characterization, molecular docking, antibacterial activity and electrochemical studies

5,5-{(1E,1E′)-1,4-Phenylenebis(diazene-2,1-diyl)}bis(quinoline-8-ol) (H 2 L1) as a new bis-bidentate azo dye primary ligand and its Mn(II) complexes were synthesized by a diazotized reaction of 1,4-diaminobenzene and 8-hydroxyquinoline in 1:2 M ratio. Incorporating of 2-aminobenzoic acid (HL 2 ) as co-ligand with the synthesized mixed ligand complexes of the composition [Mn 2 (H2L 1 )(L 2 ) 2 (X) 2 (H 2 O) 2 ]Y, X = (Cl), Y = 2.5 ( 1 ); (NO 3 ), Y = nil ( 3 ); (OAc), Y = 2 ( 4 ) and [Mn 2 (L 1 )(L 2 ) 2 (H 2 O) 4 ]4H 2 O ( 2 ) were synthesized and characterized. Mn(II) mixed ligand complexes showed polycrystalline natures in the XRD results. The antibacterial activity of H 2 L 1 , HL 2 and their mixed ligand complexes was tested against different Gram-positive and Gram-negative bacteria ( Bacillus cereus , Staphylococcus aureus , Escherichia coli , Pseudomonas sp. and Klebsiella pneumoniae ). Antifungal activity was screened against Fusarium oxysporum , Aspergillus niger and Candida albicans . Mn(II) mixed ligand complexes showed higher activity than other complexes. The cytological effects of Mn(II) mixed ligand complexes on Bacillus cereus , Escherichia coli and Aspergillus niger were studied. Molecular operating environment (MOE) is computational software used to predict and explain the interaction between ligands (H 2 L 1 , HL 2 and Mn mixed ligand complexes) and receptor proteins of crystal structures of the SARS-CoV-2 (COVID-19) main protease (6WTT), structure of isonicotinimidylated liver alcohol dehydrogenase (7ADH) and crystal structure of E. coli MenB in complex with substrate analog, OSB-NCoA (3T88). The inhibitive effect of novel bis-bidentate azo dye ligand versus C-steel and its adsorption nature was gained in HCl solution (2 M) using implemented techniques of EIS and EFM. By increasing the inhibitor dosage, the results from IE get better.