Insight into the Role of Hydrogen Bonding in the Molecular Self-Assembly Process of Sulfamethazine Solvates

The new solid forms screening of sulfamethazine was conducted in 16 kinds of different pure solvents. Four new sulfamethazine solvates were reported for the first time, and three crystal structures of solvates were successfully determined from single-crystal X-ray diffraction data. The results showed that sulfamethazine solvate formation directly depended on the solvents used in the experiments. The solvent properties were used to evaluate the effects of solvent on solvate formation. It was found that the H-bond acceptor ability of the solvent was the main factor that governed the solvate formation. The H-bonded motifs in the structures of solvates have been fully characterized. The results revealed that sulfamethazine solvate formation was mainly driven by molecular self-assembly through hydrogen bonding between solvent and solute molecules. Meanwhile, the crystal structures results also showed that the sulfamethazine molecule had flexible conformation. Furthermore, the principles of different sulfamethazine molecules packing in different crystal structures were discussed from the view of molecular intermolecular interactions and the molecular conformation.