Synthesis, spectral, thermal, antibacterial and molecular docking studies of some metal(II) complexes of 2-(1,3-benzothiazol-2-ylamino)naphthalene-1,4-dione

The ketoamine, 2-(1,3-benzothiazol-2-ylamino)naphthalene-1,4-dione(HL) and its Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Zn(II) complexes were synthesized and characterized by NMR, FTIR, and electronic spectroscopies with elemental, thermal, room temperature magnetic susceptibility, and molar conductivity measurements. The elemental, spectral, and thermal analysis corroborated the proposed molecular formulae for the complexes as [ML(OAc)]aH2O {M = Co, Ni, Cu, Zn} and [ML2]bH2O {M = Mn}. In addition, magnetic moments and electronic spectra data indicated a tetrahedral/square-planar geometry for all the metal complexes, while molar conductance measurements in DMSO established the covalent nature of the metal complexes. The in vitro antibacterial studies of the ketoamine and its metal complexes against K. oxytoca, P. aeruginosa, E. coli, B. cereus, and S. aureus showed that the compounds exhibited broad-spectrum antibacterial activities against the bacteria strains, with an inhibitory zone of 8.0–25.0 mm. Furthermore, molecular docking studies were conducted in order to examine the molecular interactions of the complexes with different enzymes of bacterial strains. The complexes showed good molecular interactions with all the receptors; phosphopentomutase, dioldehydratase, Ftsz, penicillin-binding protein 5, and peptidyl-tRNA hydrolase except for the bulky palladium complex. The results obtained from the molecular docking studies supported and provided a possible mechanistic basis for the experimentally observed antibacterial efficacies.