State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
Molecules. 2022 May 4;27(9):2933. doi: 10.3390/molecules27092933.
Counter-cations are essential components of polyoxometalates (POMs), which have a distinct influence on the solubility, stabilization, self-assembly, and functionality of POMs. To investigate the roles of cations in the packing of POMs, as a systematic investigation, herein, a series of triol-ligand covalently modified Cu-centered Anderson-Evans POMs with different counter ions were prepared in an aqueous solution and characterized by various techniques including single-crystal X-ray diffraction. Using the strategy of controlling Mo sources, in the presence of triol ligand, NH, Cu and Na were introduced successfully into POMs. When (NH)MoO was selected, the counter cations of the produced POMs were ammonium ions, which resulted in the existence of clusters in the discrete state. Additionally, with the modulation of the pH of the solutions, the modified sites of triol ligands on the cluster can be controlled to form δ- or χ-isomers. By applying MoO in the same reaction, Cu ions served as linkers to connect triol-ligand modified polyanions into chains. When NaMoO was employed as the Mo source to react with triol ligands in the presence of CuCl, two 2-D networks were obtained with {Na(HO)} or {{Na(HO)} sub-clusters as linkers, where the building blocks were δ/δ- and χ/χ-isomers, respectively. The present investigation reveals that the charges, sizes and coordination manners of the counter cations have an obvious influence on the assembled structure of polyanions.
抗衡阳离子是多金属氧酸盐（POMs）的重要组成部分，对 POMs 的溶解性、稳定性、自组装和功能有明显的影响。为了研究阳离子在 POMs 堆积中的作用，我们进行了系统的研究，本文在水溶液中制备了一系列具有不同抗衡离子的三醇配体共价修饰的 Cu 中心 Anderson-Evans POMs，并通过单晶 X 射线衍射等多种技术进行了表征。采用控制 Mo 源的策略，在三醇配体存在的条件下，成功地将 NH、Cu 和 Na 引入 POMs 中。当选择 (NH)MoO 作为 Mo 源时，所生成的 POMs 的抗衡阳离子为铵离子，导致其以离散簇的形式存在。此外，通过调节溶液的 pH 值，可以控制三醇配体在簇上的修饰位点，形成 δ-或 χ-异构体。在相同的反应中应用 MoO，Cu 离子作为链接剂将三醇配体修饰的多阴离子连接成链。当使用 MoO 作为 Mo 源，在 CuCl 存在的情况下与三醇配体反应时，得到了两个 2-D 网络，分别以 {Na(HO)} 或 {{Na(HO)} 亚簇作为链接，其中的构建块分别为 δ/δ-和 χ/χ-异构体。本研究表明，抗衡阳离子的电荷、大小和配位方式对多阴离子的组装结构有明显的影响。
