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.