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Thermodynamic and structural aspects of hydrated and unhydrated phases of 4-hydroxybenzamide

机译：4-羟基苯甲酰胺水合相和非水合相的热力学和结构方面

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Single crystals of the anhydrate and hydrate [4-OH-BZA + H2O] with 1:1 stoichiometry of 4-hydroxybenzamide (4-OH-BZA) were grown, and their structures were solved by X-ray diffraction methods. Furthermore, the temperature dependence of the vapor pressure of the anhydrate phase was obtained, and the thermodynamic parameters of sublimation were calculated (Delta G degrees(sub) = 58.9 kJ center dot mol(-1); Delta H-sub(298) = 117.8 +/- 0.6 kJ center dot mol(-1); Delta S-sub(298) = 198 +/- 12 kJ center dot mol(-1)center dot K-1). The differences in crystal lattice energies between the 2:1 and 1: 1 hydrates and the anhydrous phase were found to be 2.2 and 6.2 kJ center dot mol(-1), respectively. The absolute values of the crystal lattice energies of the outlined hydrates (Delta H-sub(298) (2:1) = 120 +/- 1 kJ center dot mol(-1); Delta H-sub(298) (1:1) = 124 +/- 1 kJ center dot mol(-1)) were obtained on the basis of sublimation and solution calorimetric experiments. Finally, the thermodynamic stability of the three crystalline phases of 4-hydroxybenzamide was estimated. In conclusion, the comparison of the crystal lattice energy of an unsolvated phase with the "stabilization" energy (an energy gain introduced by guest molecules) of the crystal lattice of an solvated phase enables a practical classification of host-guest molecular crystals when the sizes of the host and guest are comparable, thus making it difficult to find out an appropriate qualitative criterion to distinguish them.
机译：生长了化学计量为1：1的4-羟基苯甲酰胺（4-OH-BZA）的无水物和水合物[4-OH-BZA + H2O]单晶，并通过X射线衍射法解析了它们的结构。此外，获得了无水物相蒸气压的温度依赖性，并计算了升华的热力学参数（Delta G度（sub）= 58.9 kJ中心点mol（-1）; Delta H-sub（298）= 117.8 +/- 0.6 kJ中心点mol（-1）; Delta S-sub（298）= 198 +/- 12 kJ中心点mol（-1）中心点K-1）。发现2：1和1：1水合物与无水相之间的晶格能量差分别为2.2和6.2 kJ中心点mol（-1）。概述的水合物的晶格能量的绝对值（Delta H-sub（298）（2：1）= 120 +/- 1 kJ中心点mol（-1）; Delta H-sub（298）（1： 1）= 124 +/- 1 kJ中心点mol（-1））是基于升华和溶液量热实验获得的。最后，估计了4-羟基苯甲酰胺的三个结晶相的热力学稳定性。总而言之，将未溶剂化相的晶格能量与溶剂化相的晶格的“稳定化”能量（由客体分子引入的能量增益）进行比较，可以在分子筛尺寸较大时对主客体分子晶体进行实际分类主人和客人的可比性是可比的，因此很难找到合适的定性标准来区分他们。

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