Zinc(II) derivatives of N, O containing Schiff bases: synthesis, characterization, computational and biological studies

Abstract

Bidentate Schiff bases (I₁–I₉) are synthesized by condensation between substituted anilines, benzothiazoles, and 2-hydroxy aromatic aldehydes. The Zn(II) derivatives (1–9) are prepared by reacting the respective ligand and zinc acetate dihydrate in a 2:1 mole ratio in dry methanol using triethylamine as a base. They are characterized by FTIR, NMR, and single-crystal XRD techniques. The XRD data confirmed distorted tetrahedral molecular geometry for 6; the intermolecular interactions are investigated comprehensively by 3-D Hirschfeld surface analysis and 2-D fingerprint plots. The DFT studies for the compounds are conducted for geometrical and energy optimization by applying 3-21 G* and 6-311++G (d, p)/B3LYP basis sets. Molecular docking data show that ligands possess GOLD scores in the range 51.5–46.7, whereas 2 and 3 have shown good fitness score of 57.7 and 53.3, respectively, with a maximum score of 60.2 for 7. The antibacterial data for 7 shows zone of inhibition as 17.3 mm against Staphylococcus aureus and 16.3 mm against Staphylococcus epidermidis, whereas 2 exhibits maximum value of 15.6 mm against gram negative bacteria Escherichia coli. The maximum and comparable alpha amylase inhibition potential of 12.6 and 12.3% are found for 8 and 3, respectively.

Keywords:

• Zinc(II) derivatives
• Schiff bases
• X-ray Structure
• DFT Calculations
• Molecular docking

Acknowledgements

The authors are very thankful to the Department of Chemistry, Quaid-i-Azam University Islamabad for providing financial assistance and lab facilities to carry out this research work.