Semi- and thiosemicarbazide Mn(II) complexes: Characterization, DFT and biological studies

• Synthesis of H2PAPS, H2PAPT and H2PABT and their Mn(II) complexes.
• The IR spectra of ligands from DFT calculations are compared with those obtained experimentally.
• The binding energy values display the high stability of complexes.
• The antibacterial activities were also tested against Bacillus subtilis and Escherichia coli bacteria.

One NO and two NOS donor ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Mn (II) complexes were prepared from the chloride salt and characterized by conventional techniques. The isolated complexes were assigned the formulaes, [Mn(HPAPS)2], [Mn(HPAPT)Cl] and [Mn(HPABT)Cl(H2O)2], respectively. The IR study of ligands and their complexes shows that H2PAPS behaves as a mononegative tridentate via both CO of hydrazide moiety in keto and deprotonated enol form and CN (azomethine) due to enolization of CO cyanate moiety without deprotonation. H2PAPT behaves as mononegative tridentate via CO of hydrazide moiety, deprotonated thiol CS and NH group. Finally H2PABT behaves as mononegative tridentate via deprotonated enolized CO of hydrazide moiety, CO of benzoyl moiety and NH group. The IR spectra of ligands from DFT calculations are compared with those obtained experimentally. Also, HOMO, LUMO, the bond lengths, bond angles, and dipole moments have been calculated. The calculated HOMO–LUMO energy gap reveals that charge transfer occurs within the molecule. The binding energy values display the high stability of complexes. The kinetic and thermodynamic parameters were determined by Coats–Redfern and Horowitz–Metzger methods. The antibacterial activities were also tested against Bacillus subtilis and Escherichia coli bacteria. Finally, the antitumor activities of the Ligands and their Mn(II) complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells.

Cytotoxic activity of (H2PAPS), (H2PAPT), (H2PABT) and their Mn(II) complexes against human tumor cells.Figure optionsDownload as PowerPoint slide