DFT computations, spectral investigations and antimicrobial studies of Zn(II) complex with α-diketimine ligand

Abstract

A new α-diketimine ligand L and its Zn(II) complex [ZnL(bpy)]Cl2 (where, L = [(NZ)-2-nitro-N-[(1Z)-1-[(2-nitrophenyl)imino]-1-phenylpropan-2-ylidene]aniline, and bpy = 2-2′-bipyridyl) were synthesized using benzil and 2-nitroaniline. The structures of compounds were confirmed by spectral analysis and conductance measurements. The optimized geometry of Zn(II) complex was satisfactorily computed using DFT calculations with 6-311++G(2d,P) basis set. The vibrational wavenumbers were also assigned and compared with experimental results. The calculated geometrical parameters are in good agreement to the reported values. Analysis of Mulliken charge and energy difference between HOMO and LUMO was used to find out the intramolecular charge transfer of the metal complex. DFT method also helped to determine molecular electrostatic potential. Antimicrobial activities of the compounds were studied and evaluated in vitro using the bacteria E. coli (Gram negative) and organism A. Niger along with standard drug and found that the complex was showing better inhibition than L. Antifungal activity was found to be better for the complex and was comparable with standard used. Thus the change in coordination from L to complex was confirmed and that resulted in the increased activity of the complex against pathogenic microbes.

Keywords

• α-diketimines
• Zn(II)
• DFT method
• HOMO-LUMO
• Antimicrobial