Synthesis and Investigation of Bivalent Thiosemicarbazone Complexes: Conformational Analysis, Methyl Green DNA Binding and In-silico Studies

2-(3,4-dihydronaphthalen-1(2H)-ylidene)-N-ethylhydrazine-1-carbothioamide as a thiosemicarbazone derivative (HDEC) was prepared for coordination with Cd(II), Co(II) and Ni(II) ions. The obtained complexes were analyzed and their suggested formulae were [Cd(HDEC)(2)Cl-2], [Co(HDEC)(2)Cl-2] and [Ni(HDEC)(2)Cl-2]. The neutral bidentate mode of bonding via C=S and C=N groups was suggested spectrally. Regarding the Co(II) and Ni(II) complexes, the two characteristic ligand field transitions in Nujol mull as well as the magnetic moment values point to their octahedral shape. The quantum calculations obtained through DFT/B3LYP method as the atomic charges, bond lengths and bond angles confirm the priority of C(8)=S(5) and C(1)=N(6) groups in coordination. Additionally, the maps of frontiers as well as the array plot with iso-surface indicate the reduced polarity of the ligand and its Cd(II) complex. A distinguished antibacterial activity of HDEC was clearly appeared with all bacterial strains which steadily exceeds than the standard drug (Ampicillin). The IC50 values for the colorimetric assay of methyl green DNA binding detect the excellent genotoxicity of the ligand. In-silico assay via Swiss link introduced an impression on the absorption, distribution, metabolism and excretion (ADME) of all compounds. The ligand showed excellent properties that it make it in the rank of promising genotoxic agent which mainly interacted with protease enzyme. Moreover, the molecular docking versus DNA-polymerase indicates the superiority of the ligand in allosteric binding with DNA-pockets. Finally, the interaction of the ligand versus DNA-polymerase cannot being ignored either from the in-vitro or in-silico assessments. Also, the lack of complexes activity may refer to their saturation from ligand coordination which yielded octahedral forms that unable for extra-interaction with the donors of biological systems in living cells.

Automated summary

In this study, a thiosemicarbazone derivative was synthesized and coordinated with Cd(II), Co(II), and Ni(II) ions to form corresponding complexes. Spectral and quantum calculations confirmed the neutral bidentate mode of bonding via C=S and C=N groups. The ligand exhibited excellent antibacterial activity and genotoxicity, and showed good absorption, distribution, metabolism, and excretion properties. Molecular docking experiments indicated its interaction with protease enzyme and DNA-polymerase.