Spontaneous resolution of chiral polyoxometalate-based compounds consisting of 3D chiral inorganic skeletons assembled from different helical units.
Spontaneous resolution of chiral polyoxometalate-based compounds consisting of 3D chiral inorganic skeletons assembled from different helical units.
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DOI：
10.1002/chem.200800666
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
Y. Lan;Shunli Li;Xinlong Wang;Kuizhan Shao;Dong-Ying Du;Z. Su;E. Wang
中科院分区：
文献类型：
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作者：
Y. Lan;Shunli Li;Xinlong Wang;Kuizhan Shao;Dong-Ying Du;Z. Su;E. Wang
合成了四个对映体纯的三维手性POM化合物[Ni（2）（bbi）（2）（H（2）O）（4）V（4）O（12）]2 H（2）O（1 a和1 B）和[Co（bbi）（H（2）O）V（2）O（6）]（2 a和2 B）（BBI= 1，1 ′-（1，4-丁二基）双咪唑），不同的钒酸盐链，并通过水热方法合成了不同的金属中心。单晶X-射线衍射分析表明，1 a和1 B，以及2 a和2 B，分别是对映体。在图1 a和图1 B中，两种具有不同螺旋轴的钒酸盐链将Ni阳离子连接成三维手性无机骨架，这些骨架通过非手性bbi配体连接成复杂的三维3，4-连接手性自穿骨架，具有（7（2）8）（7（2）8（2）9（2））（7（3）8（2）10）拓扑结构.它们代表了已知用于聚氧乙烯酸酯（POM）系统的手性自穿透框架的第一个实例。与图1 a和图1 B相反，图2 a和图2 B中钒酸盐链连接Co（II）阳离子，生成三维手性无机骨架，这些骨架由两种手性沿着c轴相反的异金属螺旋单元组装而成。手性无机骨架通过bbi连接形成具有（6（2）8）（2）（6（2）8（2）10（2））拓扑结构的3，4-连接手性POM骨架。认为1 a-2 B中金属阳离子的不对称配位模式产生了初始手性中心，并且当手性扩展到纯手性三维网络中时，各种螺旋单元的形成和氢键相互作用负责手性的保持和自发拆分。这是已知的第一个报告的手性POM为基础的化合物组成的3D手性无机骨架通过自发拆分结晶时，在没有任何手性源，这可能提供了一个合理的策略，通过使用非手性配体和POM螺旋单元的手性POM为基础的化合物的合成。
Four enantiomerically pure 3D chiral POM-based compounds, [Ni(2)(bbi)(2)(H(2)O)(4)V(4)O(12)]2 H(2)O (1 a and 1 b) and [Co(bbi)(H(2)O)V(2)O(6)] (2 a and 2 b) (bbi=1,1'-(1,4-butanediyl)bisimidazole) based on the achiral ligand, different vanadate chains, and different metal centers have been synthesized by hydrothermal methods. Single-crystal X-ray diffraction analyses revealed that 1 a and 1 b, and 2 a and 2 b, respectively, are enantiomers. In 1 a and 1 b two kinds of vanadate chains with different screw axes link Ni cations to generate 3D chiral inorganic skeletons, which are connected by the achiral bbi ligands to form complicated 3D 3,4-connected chiral self-penetrating frameworks with (7(2)8)(7(2)8(2)9(2))(7(3)8(2)10) topology. They represent the first examples of chiral self-penetrating frameworks known for polyoxometalate (POM) systems. Contrary to 1 a and 1 b, in 2 a and 2 b the vanadate chains link Co(II) cations to generate 3D chiral inorganic skeletons, which are assembled from two kinds of heterometallic helical units of opposite chirality along the c axes. The chiral inorganic skeletons are connected by bbi to form 3D 3,4-connected chiral POM-based frameworks with (6(2)8)(2)(6(2)8(2)10(2)) topology. It is believed that the asymmetrical coordination modes of the metal cations in 1 a-2 b generate the initial chiral centers, and that the formation of the various helical units and the hydrogen bond interactions are responsible for preservation of the chirality and spontaneous resolution when the chirality is extended into the homochiral 3D-networks. This is the first known report of chiral POM-based compounds consisting of 3D chiral inorganic skeletons being obtained by spontaneous resolution upon crystallization in the absence of any chiral source, which may provide a rational strategy for synthesis of chiral POM-based compounds by using achiral ligands and POM helical units.