Synthesis, Characterization, and Antibacterial Activities of Some New Zinc Coordination Compounds of an Asymmetric Bidentate Schiff Base

Abstract

An asymmetrical Schiff base ligand with two position for coordination to metal was obtained by condensation reaction between propane-1,2-diamine and (E)-3-(4-(dimethylamino)phenyl)acrylaldehyde. Characterization of the ligand and its Zn(II) complexes were performed suitably by means of the elemental analysis, FTIR, ¹H, ¹³C NMR, UV-visible, melting points, and molar conductance. Lowering of the iminic bond energy, red shifts of electronic transition bands, and down fielded azomethine proton signals well confirm coordination of ligand to zinc center. All compounds were stable at room temperature for the many long times. All complexes were suggested to be nonelectrolytes due to low molar conductivities. After characterization, antibacterial properties of all compounds have been studied against two Gram-negative bacteria, Escherichia coli (ATCC 25922) and Pseudomonas aeroginosa (ATCC 9027), and two Gram-positive bacteria, Staphylococcus aureus (ATCC 6538) and Bacillus subtilis. The ligand and Zn(II) coordination compounds demonstrated acceptable antibacterial activities. Zinc complexes showed higher activity than the parental ligand. The compounds inhibited the growth of Gram-negative more efficiently than Gram-positive bacterial strains. MIC and MBC of all compounds as alternative data for antibacterial activity were reported in μg/mL.

Keywords:

• Schiff base
• zinc
• bidentate
• complex
• spectral
• NMR
• antibacterial