Synthesis, characterization, and biological evaluation of oxovanadium (IV) complexes with acetylacetone and trifluoro acetylacetone in the presence of substituted pyridines

A series of monomeric, six-coordinate oxovanadium (IV) complexes having the general formula [VO(RCOCH2COR′)2(L)] [where R = CH3, (CH3)4; R′ = CH3, (CF3); and L = 4-methylpyridine or 3-amino-4-hydroxypyridine), were synthesized as 1:2 substituted β-diketonate–pyridine adducts. Comprehensive characterization (magnetic susceptibility, conductivity, Mass, EPR, IR, UV–Vis and PXRD) supporting the predicted coordination environment. Antimicrobial screenings using the Kirby–Bauer method revealed that the complexes possess significantly enhanced activity against selected Gram-positive and Gram-negative bacteria as well as fungal strains compared to free ligands, attributed to increased lipophilicity via chelation. The adducts were found to be paramagnetic, with magnetic moment values at room temperature lying in the range of 1.68–1.79 BM, confirming the presence of one unpaired electron. These values are consistent with an octahedral geometry around the vanadium (IV) center. Spectroscopic data, along with magnetic measurements, strongly indicate a monomeric octahedral geometry around the vanadium (IV) ion. These complexes demonstrate potential as promising pharmacological agents. Overall, the findings highlight that these oxovanadium (IV) complexes possess promising antimicrobial properties and may serve as potential candidates for further pharmacological and medicinal investigations.