Antimicrobial Potential of a Formazanate-Based Mercury(II) Complex: In Vitro- and In Silico-Based Insights

Herein, we present a distorted square pyramidal mercury complex, [Hg^II(L)Cl] (1), based on a quinoline-substituted formazan ligand LH[3-Cyano-1,5-(quinolin-8-yl)formazan], which was evaluated for its anti-bacterial activity in vitro. Complex 1 was prepared by refluxing 3-Cyano-1,5-(quinolin-8-yl)formazan ligand and mercury chloride(II) in equimolar quantity and was characterized utilizing a range of analytical methods, including single crystal X-ray diffraction (SCXRD) technique. The crystal packing in complex 1 has been elucidated using supramolecular investigations, which have shown the presence of fascinating Hg-Cl⋅⋅⋅Hg intermolecular spodium bonds of the order 3.348 Å. The antimicrobial activity of the formazanate-based mercury(II) complex (1) was assessed against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial pathogens. In addition, the plausible therapeutic target of the formazanate-based mercury(II) complex was determined through in silico pharmacophore-guided rational drug designing approach. Based on the in silico results, a conceivable molecular mechanism of the observed bactericidal action of the newly synthesized [Hg^II(L)Cl] complex (1) has also been suggested.