Manipulation of ordered nanostructures of protonated polyoxometalate through covalently bonded modification.
Manipulation of ordered nanostructures of protonated polyoxometalate through covalently bonded modification.
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DOI：
10.1002/chem.201001674
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发表时间：
2010-11
期刊：
影响因子：
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通讯作者：
Yongliang Wang;Xiao-Le Wang;Xinjun Zhang;N. Xia;Bo Liu;Jie Yang;Wei-Ru Yu;Minbiao Hu;Miao Yang;Wei Wang
中科院分区：
文献类型：
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作者：
Yongliang Wang;Xiao-Le Wang;Xinjun Zhang;N. Xia;Bo Liu;Jie Yang;Wei-Ru Yu;Minbiao Hu;Miao Yang;Wei Wang
多金属氧酸盐(POMS)是一类独特的金属-氧簇(金属=MoVI、WVI、VIV、V等)。POMS具有无与伦比的结构体系和诱人的功能，在分析化学、催化、材料科学和医学等不同领域有着广泛的应用。然而，POMS与其他材料相对较差的相容性以及作为无机晶体材料的相对较差的加工性阻碍了传统POMS进一步设计成具有有序结构的新型材料，以优化其特定的功能。因此，在过去的几十年里，人们一直致力于通过有机基元在多聚甲醛上的共价键进行修饰。[2]已经证明，有机修饰的聚甲醛杂化材料不仅结合了有机分子和无机簇合物的优点，而且通过构建含有聚甲醛的纳米结构产生了显著的协同效应。[3]因此，探索新的共价修饰杂化材料具有重要的意义，具有一些潜在的吸引人的功能，如质子传导、电子转移和骨架材料。为了进一步促进POM在杂化材料中的应用，将适当的有机基元连接到POMS上以构建和操纵固体中含有POM的有序纳米结构是非常重要的。树枝状大分子和单枝状分子是一类最有影响力的模体，它们被广泛用于构建不同的纳米结构，能够通过控制它们独特的分子结构来程序化地操纵这些结构。[4]在过去的几十年里，一些树枝状分子被用于制备一些具有不同纳米结构的含POM的杂化材料。[5]这些研究的意义在于证明超分子结构和性质之间的相关性。然而，到目前为止，只有两个例子共价连接树状分子-聚甲醛杂化。[6]在这里，我们报道了一种新型的树状分子-聚甲醛-树枝状分子杂化材料的设计和合成，其中多金属化合物直接与两个低世代树枝状分子共价连接。通过将不同世代的树枝连接到POMS上来控制杂化产物的分子结构，我们可以构建和操纵含有大量质子化POMS的高度有序的层状或圆柱状结构。在可用的聚甲醛簇合物中，选择了Mn-Anderson POM阴离子{MnMo6O18ACHTUNGTRENNUNG[(OCH2)3CNH2]2}3±(Tris-POM-Tris)[7]的独特的tetrabuACHTUNGTRENNUNGtyl-ACHTUNGTRENNUNGammonium(Tba)盐作为起始无机构建块。重要的是，簇合物两侧的胺基可用于进一步的有机修饰。同时，第一代聚苄基醚树枝(PBE；方案1中的G1-COOH和G2-COOH)，其焦点含有一个羧基，外围含有两个或四个14-碳烷基，由于其不同的形状允许自组织成不同的有序结构，因此被选为有机构建块。[8]为了产生目标杂化分子，树枝通过胺和羧基之间的酰胺化被共价连接到Tris-POM-Tris上。在1-ethyl-3-(3-di-ACHTUNGTRENNUNGmethACHTUNGTRENNUNGylaminopropyl)碳二亚胺盐酸盐(EDC.HCl)/羟基苯并三氮唑(HOBt)存在下，在N，N-二甲基甲酰胺(DMF)中反应两周。[9]经过反复沉淀提纯，新形成的杂化…
Polyoxometalates (POMs) are a unique class of metal–oxygen clusters (metal= MoVI, WVI, VIV, V, etc.) with an unmatched range of structural architectures and attractive functionalities that give rise to a variety of applications in diverse fields, such as analytical chemistry, catalysis, materials science, and medicine.[1] Nevertheless, the relatively poor compatibility of POMs with other materials and their relatively poor processability as inorganic crystalline materials hinder the further engineering of conventional POMs into novel materials with ordered structures to optimize their specified functionalities. In previous decades, therefore, much effort has been directed towards modification through covalent linkages of organic motifs onto POMs.[2] It has been demonstrated that organically modified POM-based hybrid materials not only combine the advantages of organic molecules and inorganic clusters, but also result in a significant synergistic effect through the construction of POM-containing nanostructures.[3] Therefore, exploration of new covalently modified hybrids has great significance with some potentially attractive functions, such as proton conduction, electron transfer, and framework materials. To further facilitate POM applications in hybrid materials, it is important to attach appropriate organic motifs to POMs to constitute and manipulate POM-containing ordered nanostructures in the solid state. Dendrimers and monodendrons are a class of the most influential motifs widely employed in the construction of diverse nanostructures that are able to be programmatically manipulated by controlling their unique molecular architectures.[4] In past decades, some dendrons have been employed in the fabrication of some POM-containing hybrids with diverse nanostructures.[5] The significance of these studies is to demonstrate the correlation between supramolecular structures and properties. However, so far there are only two examples of covalently connected dendron–POM hybrids.[6] Herein, we report the novel design and synthesis of a new type of dendron-POM-dendron hybrid in which the POMs are directly covalently linked with two low-generation dendrons. By controlling molecular structure of the hybrids by linking different generation dendrons to the POMs, we can construct and manipulate highly ordered layer or cylinder structures that contain the protonated POMs in bulk samples. Of the available POM clusters, the distinctive tetrabuACHTUNGTRENNUNGtyl-ACHTUNGTRENNUNGammonium (TBA) salt of the Mn-Anderson POM anion {MnMo6O18ACHTUNGTRENNUNG [(OCH2) 3CNH2] 2} 3À (Tris-POM-Tris)[7] was selected as the starting inorganic building block. Importantly, the amine groups on the both sides of the cluster can be used for further organic modification. Meanwhile, the firstand second-generation dendrons of poly (benzyl ether)(PBE; g1-COOH and g2-COOH in Scheme 1), which contain a carboxyl group at their focal point and two or four 14-carbon alkyl groups on the periphery, were selected as the organic building blocks because their different shapes allow self-organization into diverse ordered structures.[8] To create the target hybrid molecules, the dendrons were covalently linked to Tris-POM-Tris by amidation between amine and carboxyl groups. The reaction was performed at room temperature for two weeks in the presence of 1-ethyl-3-(3-di-ACHTUNGTRENNUNGmethACHTUNGTRENNUNGylaminopropyl) carbodiimide hydrochloride (EDC· HCl)/ACHTUNGTRENNUNG1-hydroxybenzotrizole (HOBt) in N, N-dimethylform-ACHTUNGTRENNUNGamide (DMF).[9] After careful purification by repeated precipitation, newly formed hybrids …