A new coordination polymer was synthesized hydrothermally using 4,4′-dimethoxy-3,3′-biphenyldicarboxylic acid (H₂dmbpdc) and Ca(NO₃)₂·4H₂O. The structure of the new compound, Ca(dmbpdc)(H₂O)₂ (CPO-70-Ca), was determined from powder X-ray diffraction (PXRD) data using simulated annealing, followed by Rietveld refinement of the structure. The framework is based on one-dimensional metal carboxylate chains that are linked by the organic linker into a three-dimensional network with rhombic channels. The as-synthesized material resembles our recently reported compound CPO-69-Ca, and shares the same sra topology. The asymmetric unit comprises one calcium atom, one fully deprotonated linker, one water molecule coordinated to the metal cation as well as one solvent water molecule located in the rhombic channels. The metal cation is eight-coordinate, forming an irregular coordination polyhedron. The thermal behavior of CPO-70-Ca was investigated in an in situ structural analysis by variable temperature powder X-ray diffraction. This study revealed an interesting response to solvent removal from the as-synthesized structure. The results include a partially desolvated version of CPO-70-Ca and a structural transformation to CPO-69-Ca upon full desolvation.

中文翻译：

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使用同步加速器粉末X射线衍射数据的新型Ca（II）3D配位聚合物的从头算结构解和热稳定性评估

使用4,4'-二甲氧基-3,3'-联苯二甲酸（H ₂ dmbpdc）和Ca（NO ₃）₂ ·4H ₂ O水热合成了一种新的配位聚合物。新化合物Ca（dmbpdc）的结构（H ₂ O）₂（CPO-70-Ca）是使用模拟退火从粉末X射线衍射（PXRD）数据确定的，然后进行Rietveld精炼结构。该框架基于一维金属羧酸盐链，该链通过有机连接基连接到具有菱形通道的三维网络中。合成后的材料类似于我们最近报道的化合物CPO-69-Ca，并且具有相同的sra拓扑。不对称单元包含一个钙原子，一个完全去质子化的连接基，一个与金属阳离子配位的水分子以及一个位于菱形通道中的溶剂水分子。金属阳离子是八配位的，形成不规则配位的多面体。通过变温粉末X射线衍射在原位结构分析中研究了CPO-70-Ca的热行为。这项研究揭示了对从合成结构中去除溶剂的有趣反应。结果包括部分去溶剂化的CPO-70-Ca和完全去溶剂化后向CPO-69-Ca的结构转变。