Molecular dynamics simulation of aspirin dissolution
Molecular dynamics simulation of aspirin dissolution
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阿司匹林溶出的分子动力学模拟
DOI：
10.1016/j.molliq.2017.11.009
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发表时间：
2017
影响因子：
6
通讯作者：
G. Patey
中科院分区：
文献类型：
--
作者：
A. Anand;G. Patey
报道了阿司匹林在水中溶解的分子动力学模拟。晶体最初立方和圆柱形的形状被认为是，和温度的影响进行了检查。所有的模拟都是以一种设计成防止溶液中阿司匹林的任何显著浓度的积累的方式进行的，物理上对应于沉降条件。结果发现，阿司匹林的溶解遵循三个阶段的机制，在大多数方面类似于早期观察到的NaCl和尿素的纳米晶体。在初始阶段，分子首先从晶体的角落和边缘丢失，晶体被溶液退火成特定的限制形状，然后在溶解过程的大部分时间内持续存在。对于阿司匹林，最初立方晶体退火成圆柱形，与立方NaCl和尿素晶体获得的近球形形状相反。在中间阶段，在此期间，大部分的晶体溶解，溶解速率是很好地描述了一个简单的经典模型，假设该速率是成比例的晶体的活性表面积。对于阿司匹林，活性表面积被确定为两种晶体形状的圆柱体的弯曲表面。在最后阶段，小的剩余晶体失去其结构并迅速溶解。考虑到类似的三阶段机制适用于NaCl、尿素和阿司匹林等不同的晶体，我们推测这种机制可能相当普遍，并可能适用于许多离子和分子晶体。至于NaCl和尿素，与阿司匹林溶解相关的活化能的分析强烈表明，从晶体中分离的分子是速率决定步骤，至少在水槽条件下。
Molecular dynamics simulations of the dissolution of aspirin in water are reported. Crystals initially cubic and cylindrical in shape are considered, and the influence of temperature is examined. All simulations are carried out in a manner designed to prevent the build up of any significant concentration of aspirin in solution, physically corresponding to sink conditions. It is found that aspirin dissolution follows a three stage mechanism similar in most respects to earlier observations for nanocrystals of NaCl and urea. In the initial stage, molecules are first lost from corners and edges of the crystal, the crystal is solution annealed into a particular limiting shape, that then persists throughout a large fraction of the dissolution process. For aspirin, initially cubic crystals anneal into a cylindrical shape, in contrast with the near spherical shapes attained by cubic NaCl and urea crystals. In an intermediate stage, during which most of the crystal dissolves, the dissolution rate is well described by a simple classical model which assumes that the rate is proportional to the active surface area of the crystal. For aspirin, the active surface area is identified as the curved surface of a cylinder for both crystal shapes. In the final stage, the small remaining crystal looses its structure and rapidly dissolves. Given that a similar three stage mechanism applies to crystals as varied as NaCl, urea, and aspirin, we conjecture that this mechanism is possibly quite general, and might apply to many ionic and molecular crystals. As for NaCl and urea, an analysis of the activation energy associated with aspirin dissolution strongly suggests that detachment of molecules from the crystal is the rate determining step, at least under the sink conditions.
影响因子：
4.9
作者：
Greiner, Maximilian;Elts, Ekaterina;Briesen, Heiko
通讯作者：
Briesen, Heiko