The hybrid compound [Cu(cyclam)(H₂O)₂]_0.5[{Cu(cyclam)}_1.5{B-H₂As₂Mo₆O₂₆(H₂O)}]·9H₂O (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane) was synthesized in aqueous solution by reacting the {Cu(cyclam)}²⁺ complex with a mixture of heptamolybdate and an arsenate(V) source. Crystal packing of 1 exhibits a supramolecular open-framework built of discrete covalent molybdoarsenate/metalorganic units and additional [Cu(cyclam)(H₂O)₂]²⁺ cations, the stacking of which generates squarelike channels parallel to the z axis with an approximate cross section of 10 × 11 Ų where all the hydration water molecules are hosted. Thermal evacuation of solvent molecules yields a new anhydrous crystalline phase, but compound 1 does not preserve its single-crystalline nature upon heating. However, when crystals are dehydrated under vacuum, they undergo a structural transformation that proceeds via a single-crystal-to-single-crystal pathway, leading to the anhydrous phase [{Cu(cyclam)}₂(A-H₂As₂Mo₆O₂₆)] (2). Total dehydration results in important modifications within the inorganic cluster skeleton which reveals an unprecedented solid-state B to A isomerization of the polyoxoanion. This transition also involves changes in the Cu^II bonding scheme that lead to covalent cluster/metalorganic layers by retaining the open-framework nature of 1. Compound 2 adsorbs ambient moisture upon air exposure, but it does not revert back to 1, and the hydrated phase [{Cu(cyclam)}₂(A-H₂As₂Mo₆O₂₆)]·6H₂O (2h) is obtained instead. Structural variations between 1 and 2 are reflected in electron paramagnetic resonance spectroscopy measurements, and the permanent microporosity of 2 provides interesting functionalities to the system such as the selective adsorption of gaseous CO₂ over N₂.

中文翻译：

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微孔砷酸钼 (V)-金属有机框架中的单晶到单晶簇的转化

杂化化合物[Cu(cyclam)(H ₂ O) ₂ ] _0.5 [{Cu(cyclam)} _1.5 { B -H ₂ As ₂ Mo ₆ O ₂₆ (H ₂ O)}]·9H ₂ O ( 1 ) ( cyclam = 1,4,8,11-四氮杂环十四烷）是在水溶液中通过 {Cu(cyclam)} ^{2+ 配合}物与七钼酸盐和砷酸盐 (V) 源的混合物反应合成的。1 的晶体堆积表现出由离散共价砷酸钼/金属有机单元和额外的 [Cu(cyclam)(H ₂ O) ₂ ]构建的超分子开放框架²⁺阳离子，其堆叠产生平行于z轴的方形通道，横截面约为 10 × 11 Å ²，所有水合水分子都位于其中。溶剂分子的热排空产生新的无水结晶相，但化合物1在加热时不会保持其单晶性质。然而，当晶体在真空下脱水时，它们会经历通过单晶到单晶途径进行的结构转变，导致无水相 [{Cu(cyclam)} ₂ ( A -H ₂ As ₂ Mo ₆ O ₂₆ )] ( 2）。完全脱水导致无机簇骨架内的重要改性，这揭示了多氧阴离子前所未有的固态B到A异构化。这种转变也涉及在铜变化^II结合方案铅共价簇/金属有机层通过保留的开框架性质1。化合物2暴露在空气中会吸附环境水分，但不会恢复为1，水合相 [{Cu(cyclam)} ₂ ( A -H ₂ As ₂ Mo ₆ O ₂₆ )]·6H ₂ O ( 2h) 代替。1和2之间的结构变化反映在电子顺磁共振光谱测量中，并且2的永久微孔性为系统提供了有趣的功能，例如气态 CO ₂对 N ₂的选择性吸附。