Co-crystal of nadifloxacin with oxalic acid

The 2:1 co-crystal of nadifloxacin [systematic name: 9-fluoro-8-(4-hy­droxy­piperidin-1-yl)-5-methyl-1-oxo-6,7-di­hydro-1H,5H-pyrido[3,2,1-ij]quinoline-2-carb­oxy­lic acid] with oxalic acid, C(19)H(21)FN(2)O(4)·0.5C(2)H(2)O(4), was prepared by slow evaporation from a chloro­form:acetone solvent system. Nadifloxacin belongs to the group of anti­bacterial drugs. The co-crystal is stabilized through an intra­molecular O—H⋯O bond and inter­molecular hydrogen bonds. It was studied by FT–IR spectroscopy, differential scanning calorimetry and X-ray diffraction. Hirshfeld surface analysis indicated that the major contribution to the packing is from O⋯H/H⋯O inter­actions.