Synthesis, Biological Activity, and the Effect of Ionization Radiation on the Spectral, XRD, and TGA Analysis of Cu(I), Cu(II), Zn(II), and Cd(II) Complexes

New complexes of molecular formulae of [Cu(H2L1)I] (B1), [Cu(H2L)2(ClO4)2](B2), [Zn (H2L)2(H2O)]SO4(B3) and [Cd(H2L)Cl]Cl(B4) of ligand N-phenyl-2-(p-tolylglycyl)hydrazine -1-carbothioamide (B) have been prepared and characterized by 1H-NMR, Mass spectra, FT-IR, elemental analyses, molar conductance, UV–visible spectra, magnetic susceptibility measurements, thermogravimetric analysis (TGA/DTG) and X-ray powder diffraction before and after irradiation. Elemental analyses indicate that the metal complexes have 1:1 (metal/ ligand) (B1 and B4) or 1:2 stoichiometry for complexes (B2 and B3). The results confirmed that gamma ray enhanced the stability of irradiated compounds as compared to non-irradiated compounds. XRD patterns proved that increasing the crystallinity of the samples and the particles is in nanosize range before and after gamma irradiation. These studies revealed that Cu(II) and Zn(II) complexes adopted octahedral geometry, and Cu(I) and Cd(II) complexes were found to be tetrahedral. The theoretical conformational structure analyses were performed using density functional theory for ligand and complexes at B3LYP functional with 6–31G basis set for ligand and LANL2DZ basis set for complexes. The ligand (B, A) and complexes (B1–B4) and (A1–A4) before and after irradiated have been tested for their inhibitory effect on the growth of bacteria against gram-positive (Streptococcus pyogenes) and gram-negative (Escherichia coli). Molecular docking investigation proved that the Zn(II) complex had interesting interactions with active site amino acids of topoisomerase II DNA gyrase enzymes (code: 2XCT).