A novel series of mixed-ligand complexes of the type, [M(L1)(L2)Cl]·2H2O [L1 = 2-(α-methyl salicylidene hydrazine) benzimidazole (primary ligand), L2 = 2,2′-bipyridine (bipy; secondary ligand), M = Co(ii), Ni(ii), Cu(ii) and Zn(ii)], were based on the physicoanalytical studies. The spectroscopic findings revealed tridentate nature of the Schiff base ligand (L1) and its coordination to the metal ions via azomethine nitrogen, ring nitrogen and the deprotonated phenolic oxygen atoms. Furthermore, the synthesized compounds were evaluated for antimicrobial activity against Bacillus subtilis, Escherichia coli and Salmonella typhi microorganisms. In addition, molecular docking studies were carried out against Middle East respiratory syndrome coronavirus (PDB ID: 4ZS6) and severe acute respiratory syndrome coronavirus 2 main protease (PDB ID: 6W63).

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ABSTRACT. A series of ternary complexes with a Schiff base (HL1) derived from 2-hydrazinobenzimidazole and o-hydroxybenzophenone (primary ligand) have been prepared. Here, 1,10-phenanthroline acts as secondary ligand (L2). These metal complexes were investigated by UV-Vis, IR, 1H NMR and thermal techniques. The spectral data confirmed tridentate nature of the SB ligand with NNO type coordination, whereas the secondary ligand L2 (1,10-phenanthroline) coordinated through its two nitrogen atoms (NN type). These compounds possess distorted octahedral geometry. Moreover, these compounds were screened against B. subtilis and E. coli to evaluate their antibacterial activity. In addition, molecular docking studies were performed against MERS-CoV and SARS-CoV-2 main protease (Mpro). Moreover, DFT calculations and QSAR studies of the SB ligand were also performed.                     KEY WORDS: Ternary complexes, Spectral, Antibacterial, DFT, QSAR, Molecular docking studies   Bull. Chem. Soc. Ethiop. 2021, 35(3), 525-535. DOI: https://dx.doi.org/10.4314/bcse.v35i3.5