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首页> 外文期刊>Crystal growth & design >Phase Formation Study of Ca-Terephthalate MOF-Type Materials
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Phase Formation Study of Ca-Terephthalate MOF-Type Materials

机译：对苯二甲酸钙MOF型材料的相形成研究

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摘要

Ca(BDC)(DMF)(H2O) with square lattice topology (sql) and rhombic-shaped channels crystallizes under solvothermal conditions (H2O/DMF mixture) in orthorhombic (Ca-BDC-orth) and triclinic (Ca-BDC-tric) conformations. The latter structure is solved and described here for the first time. The main difference between the two phases lies in the orientation of the coordinated DMF molecule located within the channels of the structure, influencing their porosity properties. In spite of the small deviances in crystal structure, the formation of individual phases can be controlled by the amount of base agent (TEA) and the temperature of crystallization. Triclinic phase is formed at lower synthesis temperature, and it is transformed into orthorhombic phase at increased temperatures. Systematic phase formation study varying TEA/Ca2+ molar ratios and the synthesis temperature showed that higher temperature of the synthesis is required for the Ca-BDC-orth phase to occur from Ca-BDC-tric using the TEA/Ca2+ ratio between 0.63-1.30 compared to the syntheses with TEA/Ca2+ values out of this range. Within the range of 0.63-1.30 the dissociation of the base is in the buffer region indicating that stability of triclinic phase is related to the thermodynamics at equilibrium conditions.
机译：具有方晶格拓扑（sql）和菱形通道的Ca（BDC）（DMF）（H2O）在斜方晶系（Ca-BDC-orth）和三斜晶系（Ca-BDC-tric）的溶剂热条件下（H2O / DMF混合物）结晶。构象。后面的结构在这里是第一次解决和描述。两相之间的主要区别在于配体DMF分子的取向位于结构的通道内，从而影响其孔隙率特性。尽管晶体结构存在小偏差，但可以通过碱试剂（TEA）的量和结晶温度来控制各个相的形成。三斜晶相在较低的合成温度下形成，并在较高的温度下转变为正交晶相。系统相形成研究不同的TEA / Ca2 +摩尔比和合成温度表明，使用0.63-1.30之间的TEA / Ca2 +比，从Ca-BDC-tric生成Ca-BDC-正相需要更高的合成温度。 TEA / Ca2 +值超出此范围的合成。在0.63-1.30的范围内，碱的解离在缓冲区域中，表明三斜晶相的稳定性与平衡条件下的热力学有关。

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