Аннотация
This work reports a new acetonitrile (ACN)-solvated cocrystal of piroxicam (PRX) and succinic acid (SA), 2C15H13N3O4S·0.5C4H6O4·C2H3N or PRX:SA:ACN (4:1:2), which adopts the triclinic space group P. The outcome of crystallization from ACN solution can be controlled by varying only the PRX:SA ratio, with a higher PRX:SA ratio in solution unexpectedly favouring a lower stoichiometric ratio in the solid product. In the new solvate, zwitterionic (Z) and non-ionized (NI) PRX molecules co-exist in the asymmetric unit. In contrast, the nonsolvated PRX–SA cocrystal contains only NI-type PRX molecules. The ACN molecule entrapped in PRX–SA·ACN does not form any hydrogen bonds with the surrounding molecules. In the solvated cocrystal, Z-type molecules form dimers linked by intermolecular N—H…O hydrogen bonds, whereas every pair of NI-type molecules is linked to SA via N—H…O and O—H…N hydrogen bonds. Thermogravimetry and differential scanning calorimetry suggest that thermal desolvation of the solvate sample occurs at 148 °C, and is followed by recrystallization, presumably of a multicomponent PRX–SA structure. Vibrational spectra (IR and Raman spectroscopy) of PRX–SA·ACN and PRX–SA are also used to demonstrate the ability of spectroscopic techniques to distinguish between NI- and Z-type PRX molecules in the solid state. Hence, vibrational spectroscopy can be used to distinguish the PRX–SA cocrystal and its ACN solvate.
Язык оригинала | английский |
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Страницы (с-по) | 29-37 |
Число страниц | 9 |
Журнал | Acta Crystallographica Section C: Structural Chemistry |
Том | 75 |
Номер выпуска | 1 |
DOI | |
Состояние | Опубликовано - 1 янв 2019 |