Crystal structure and characterization of the sul­fa­methazine–pi­peri­dine salt

Sulfamethazine [N (1)-(4,6-di­methyl­pyrimidin-2-yl)sulfanilamide] is an anti­micro­bial drug that possesses functional groups capable of acting as hydro­gen-bond donors and acceptors, which make it a suitable supra­molecular building block for the formation of co­crystals and salts. We report here the crystal structure and solid-state characterization of the 1:1 salt pi­peri­dinium sul­fa­methazinate (PPD(+)·SUL(−), C(5)H(12)N(+)·C(12)H(13)N(4)O(2)S(−)) (I). The salt was obtained by the solvent-assisted grinding method and was characterized by IR spectroscopy, powder X-ray diffraction, solid-state (13)C NMR spectroscopy and thermal analysis [differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)]. Salt I crystallized in the monoclinic space group P2(1)/n and showed a 1:1 stoichiometry revealing proton transfer from SUL to PPD to form salt I. The PPD(+) and SUL(−) ions are connected by N—H(+)⋯O and N—H(+)⋯N inter­actions. The self-assembly of SUL(−) anions displays the amine–sulfa C(8) motif. The supra­molecular architecture of salt I revealed the formation of inter­connected supra­molecular sheets.