Interaction of vanadium (IV) solvates (L) with second-generation fluoroquinolone antibacterial drug ciprofloxacin: Spectroscopic, structure, thermal analyses, kinetics and biological evaluation (L = An, DMF, Py and Et3N)

•Synthesis and isolation of some new complexes with ciprofloxacin as antibacterial agent.•Characterization of the isolated solid complexes by different spectroscopic techniques.•Studying the effect of L on the antibacterial agent ciprofloxacin and also if it increasing or decreasing the activity of antibiotic ciprofloxacin inside the human body.•Kinetic study of all prepared complexes.

The preparation and characterization of the new solid complexes [VO(CIP)2L]SO4⋅nH2O, where L = aniline (An), dimethylformamide (DMF), pyridine (Py) and triethylamine (Et3N) in the reaction of ciprofloxacin (CIP) with VO(SO4)2·2H2O in ethanol. The isolated complexes have been characterized with their melting points, elemental analysis, IR spectroscopy, magnetic properties, conductance measurements, UV–Vis. and 1H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that ciprofloxacin reacts as a bidentate ligand bound to the vanadium ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E*; entropies, ΔS*; enthalpies, ΔH*; Gibbs free energies, ΔG*, of the thermal decomposition reactions have been derived from thermo gravimetric (TGA) and differential thermo gravimetric (DTG) curves, using Coats–Redfern and Horowitz–Metzeger methods. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand and their metal complexes were also evaluated for their antibacterial activity against several bacterial species, such as Bacillus Subtilis (B. Subtilis), Staphylococcus aureus (S. aureus), Nesseria Gonorrhoeae (N. Gonorrhoeae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli).

Graphical abstractFour vanadium(IV) complexes with ciprofloxacin drugs are synthesized. IR, UV–Vis, 1HNMR, kinetic study and thermal analyses techniques are used. Antibacterial behavior is evaluated against Gram-positive and Gram-negative bacterial strains.Figure optionsDownload full-size imageDownload as PowerPoint slide