First examples of aliphatic zirconium MOFs and the influence of inorganic anions on their crystal structures
作者:Helge Reinsch、Ivo Stassen、Bart Bueken、Alexandra Lieb、Rob Ameloot、Dirk De Vos
DOI:10.1039/c4ce01457j
日期:——
Utilizing the aliphatic linker molecule adipic acid (1,6-hexanedioic acid, HO2C–C4H8–CO2H) or 3-methyladipic acid (racemic mixture, HO2C–C4H7CH3–CO2H), the first crystalline zirconium adipates were synthesized under aqueous conditions. Their structures were deduced from powder X-ray diffraction data and were confirmed by Rietveld refinements. For all three compounds, the inorganic nodes are related to the well-known Zr6O4(OH)4 cluster frequently observed in aromatic zirconium MOFs. Employing ZrOCl2·8H2O and 3-methyladipic acid, a framework with bcu topology was obtained. Starting from adipic acid and Zr(SO4)2·4H2O, we observed the incorporation of sulfate into the crystal structure. Four sulfate anions are coordinated to each Zr–oxo cluster in a bidentate fashion. In this complex structure, square grids formed by Zr–oxo clusters and adipate anions and furthermore a hydrogen-bonded inorganic dia net can be observed. The third compound presented here is structurally related to the zirconium methyladipate. Using adipic acid and adding CrO42− under strongly acidic conditions leads to the incorporation of Cr2O72− into the bcu net. The dichromate anions are coordinated twofold to two different Zr–oxo clusters in a monodentate fashion and thus serve as inorganic connectors between the framework's nodes.
利用脂肪族连接分子己二酸(1,6-己二酸,HO2C-C4H8-CO2H)或 3-甲基己二酸(外消旋混合物,HO2C-C4H7CH3-CO2H),在水溶液条件下合成了首批结晶己二酸锆。根据粉末 X 射线衍射数据推断出了它们的结构,并通过里特维尔德精炼得到了证实。所有这三种化合物的无机节点都与芳香族锆 MOFs 中经常出现的著名 Zr6O4(OH)4 簇有关。利用 ZrOCl2-8H2O 和 3-甲基己二酸,得到了具有 bcu 拓扑结构的框架。从己二酸和 Zr(SO4)2-4H2O 开始,我们观察到晶体结构中加入了硫酸盐。四个硫酸根阴离子以双齿方式配位到每个 Zr-oxo 簇上。在这种复杂的结构中,可以观察到由 Zr-oxo 团簇和己二酸阴离子形成的方形网格,以及进一步的氢键无机二重网。本文介绍的第三种化合物在结构上与甲基己二酸锆有关。在强酸性条件下使用己二酸并加入 CrO42-,会导致 Cr2O72- 加入到 bcu 网中。重铬酸盐阴离子与两个不同的 Zr-oxo 团簇以单配位方式配位,因此成为框架节点之间的无机连接体。