Two salts and the salt cocrystal of ciprofloxacin with thiobarbituric and barbituric acids: The structure and properties

Ciprofloxacin (CfH, C₁₇H₁₈FN₃O₃) crystallizes with 2-thiobarbituric (H₂tba) and barbituric acid (H₂ba) in the aqueous solution to yield salt CfH₂(Htba)·3H₂O (1), salt cocrystal CfH₂(Hba)(H₂ba)·3H₂O (2), and salt CfH₂(Hba)·H₂O (3). The compounds are structurally characterized by the X-ray single-crystal diffraction. The numerous intermolecular hydrogen bonds N–H⋯O and O–H⋯O formed by water molecules, Htba⁻/Hba⁻ and CfH₂ ⁺ ions, and H₂ba molecules stabilize the crystal structures of 1 to 3. Hydrogen bonds form a 2D plane network in the salts of 1 and 3 and a 3D network in the salt cocrystal of 2. There are different π-π interactions in 1 to 3. The compounds have been characterized by powder X-ray diffraction, thermogravimetry/differential scanning calorimetry, and Fourier transform infrared spectroscopy. The compounds dehydration ends at 130°C to 150°C, and their oxidative decomposition is observed in the range of 250°C to 275°C.