Nanoadditivetech LLC, Commack, New York 11725.
Jiangsu Collaborative Innovation Center for Biological Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China; Jiangsu Key Laboratory of Biofunctional Materials, Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing 210023, China.
J Pharm Sci. 2018 Nov;107(11):2804-2809. doi: 10.1016/j.xphs.2018.06.023. Epub 2018 Jun 30.
A hydrate of co-crystal of piracetam and 3,5-dihydroxybenzoic acid was obtained via crystallization from water. Single-crystal X-ray data show that piracetam/3,5-dihydroxybenzoic acid tetrahydrate (P35TH) crystallizes in the triclinic system with a P1 space group. The physicochemical properties of co-crystal hydrate were characterized using powder X-ray diffractometry, differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and FTIR spectroscopy. The dehydration kinetics of P35TH was monitored at various temperatures and heating rates by DSC and TGA. Activation energy of P35TH dehydration was obtained using temperature ramp DSC, isothermal and nonisothermal TGA methods. Kinetic analysis of isothermal TGA data was fitted to various solid-state reaction models. Mechanistic models derived from isothermal dehydration kinetic data are best described as a 2-dimensional diffusion mechanism. A correlation was noted between the dehydration behavior and the bonding environment of the water molecules in the crystal structure. This study is a good demonstration of complexity of co-crystal hydrate and their dehydration behavior.
通过水结晶得到吡拉西坦和 3,5-二羟基苯甲酸共晶水合物。单晶 X 射线数据表明，吡拉西坦/3,5-二羟基苯甲酸四水合物（P35TH）以 P1 空间群结晶在三斜晶系中。使用粉末 X 射线衍射法、差示扫描量热法（DSC）、热重分析仪（TGA）和傅里叶变换红外光谱法对共晶水合物的物理化学性质进行了表征。通过 DSC 和 TGA 在不同温度和加热速率下监测 P35TH 的脱水动力学。使用温度斜坡 DSC、等温和非等温 TGA 方法获得 P35TH 脱水的活化能。等温 TGA 数据的动力学分析拟合了各种固态反应模型。来自等温脱水动力学数据的机理模型最好描述为二维扩散机制。注意到脱水行为与晶体结构中水分子的键合环境之间存在相关性。该研究很好地展示了共晶水合物及其脱水行为的复杂性。
