Redox behavior, spectroscopic investigations, theoretical interpretation and biological effectiveness of some novel prepared bis-azomethine derivatives and their copper(II) complexes

Abstract

Three new bis-azomethine derivatives were synthesized in a good yield, along with their copper(II) complexes and confirmed by IR, ¹³C-NMR, ¹H-NMR, MS, ESR, powder XRD and UV-vis spectroscopy. The spectral studies indicated that the ligands in all complexes act as dibasic tetradentate, coordinated through two azomethine nitrogen and two deprotonated phenolic oxygen atoms. Square planar geometries were assigned for Cu(II) complexes in monomeric structures. Also, quantum chemical calculations using DFT were conducted to elucidate the effect of quantum chemical parameters on the molecular and electronic structures of the molecules under consideration, and then confirming their electrochemical behavior and biological effectiveness. There were good correlations between practical and theoretical studies. The redox pathway of bis-azomethine derivatives and their Cu(II) complexes was elucidated and confirmed based on experimental and theoretical calculations. In vitro antimicrobial effectiveness of the synthesized three ligands and their Cu(II) complexes exhibited varying degrees of inhibitory effect on the growth of the test pathogenic microorganisms, confirming that antimicrobial efficiency is dependent on the molecular structure of the prepared compounds and their liposolubility. The MIC was also determined for the compound H₂L_c which exhibited the highest antimicrobial activity against each of Pseudomonas aeruginosa (G-) and Candida albicans.

Graphical Abstract

Keywords:

• Bis-azomethine Cu(II) complex derivatives
• spectroscopic investigations
• redox behavior
• biological effectiveness
• theoretical elucidation

Acknowledgement

The authors also express their gratitude to Prof. Mohamed Khald Awad, Chemistry Department, Faculty of Science, Tanta University, for providing the help in computational studies.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This article was funded by the Deanship of Scientific research (DSR), King Abdulaziz University, Jeddah under grant no. (1432/247/100). The authors, therefore, acknowledge with thanks DSR technical and financial support.