A molybdenum-ciprofloxacin complex with an isopolyoxometalate having DNA binding and antibacterial activity

In this study, an antibacterial complex based on the quinolone antibacterial drug ciprofloxacin (CF) and a polyoxometalate was synthesized, Mo2O5(CF)2(CFd)2(β-Mo8O26)·5H2O (1). Complex 1 was characterized by elemental analysis and X-ray single-crystal diffraction. Single-crystal structural analysis revealed that 1 was made of β-Mo8 clusters, binuclear molybdenum clusters Mo2O5(CF)2(CFd)2, and water molecules. The antibacterial activity of 1 has been tested against three microorganisms (Staphylococcus aureus, Escherichia coli, and Bacillus subtilis strains); the antibacterial activities of 1 were higher than those of free CF at the same mass amounts. The interaction between 1 and calf thymus DNA (CT-DNA) was investigated using Uv-vis spectroscopy to determine the binding constants. The results indicated that intercalation is the probable mode of action, with 1 demonstrating higher binding constants (Kb) to CT-DNA (1.8 × 105 M−1) compared to pure CF (4.9 × 104 M−1). These findings show that the implementation of molybdate for ciprofloxacin modification resulted in the formation of a metal complex with enhanced antibacterial activity over CF and significantly improving its binding affinity to DNA.