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一、分子晶体转型的热力学基本原理由分子结晶构成的固体物质,可以用分子之间势能为基础的近似模型来描述。这种模型成功地用于计算转变热与转变温度,有时还可用于计算在转变中所产生的体积变化。但这种模型是半经验性的。这里的着重点是,用这种模型来解释近200多种晶型转变,并为判别药物多晶型的相对稳定性提供依据。 1.晶体转型的能一温相图: 设一体系中有A、B两种晶型,在常压下,A型在0°K处较B型稳定。A、B两型的热力学变化关系由图1表示。T_P为转变温度,即在这点上,A、B两型的克分子自由能相等。
First, the basic principle of thermodynamics of molecular crystal transformation Solid material composed of molecular crystallization can be described by the approximate model based on the potential energy between molecules. This model was successfully used to calculate the transition heat and the transition temperature, and sometimes also used to calculate the volume change produced during the transition. But this model is semi-empirical. The emphasis here is on using this model to explain nearly 200 polymorphic transformations and provide a basis for discriminating the relative stability of drug polymorphs. 1. Crystalline energy transformation can be a phase diagram: set a system in A, B two crystal forms, at atmospheric pressure, A type at 0 ° K at B-type stability. A, B two types of thermodynamic changes shown in Figure 1. T_P for the transition temperature, that is, at this point, A, B two types of molecular free energy equal.