Structural and theoretical exploration of an innovative unsymmetrical oxovanadium complex: Electrochemical analysis and in vitro antibacterial screening

Abstract

2‑hydroxy-1-naphthaldehyde and 3,4-diaminotoluene were reacted with bis(acetylacetonato) oxovanadium to yield a novel NNOO -type chelate complex, VOL. The prepared complex is characterized by employing elemental analysis, electronic and infrared spectra. The expected structure was crystallized and identified by using the single-crystal X-ray diffraction method. The VOL complex crystallizes in the monoclinic system with the P21/c space group. Additionally, we affected a comprehensive analysis of VOV, VOIV and VOIII complexes focusing on their structural, electronic, and optical properties using DFT and TD-DFT calculations in gas. The computed parameters closely matched the experimental data, demonstrating good agreement. The electrochemical behavior of the VOL complex, investigated on a glassy carbon electrode (GCE) by means of cyclic voltammetry (CV), revealing a metal-centered one-electron redox systems corresponding to the VOIV/VOIII and VOV/VOIV at -1206 and 547 mV/SCE respectively. The in vitro antibacterial activities of the free ligand H2L and the corresponding VOL complex were evaluated against Gram-positive strains, Staphylococcus aureus and Streptococcus pyogenes, and Gram-negative strains, Escherichia coli, Proteus mirabilis and Klebseilla pneumoniae. The biological screening revealed that the VOL complex exhibits more potent activity than the free ligand.