Inclusion of Anionic Guests inside a Molecular Cage with Palladium(II) Centers as Electrostatic Anchors
Inclusion of Anionic Guests inside a Molecular Cage with Palladium(II) Centers as Electrostatic Anchors
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DOI：
10.1002/anie.200902717
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Shionoya, Mitsuhiko
中科院分区：
文献类型：
--
作者：
Clever, Guido H.;Tashiro, Shohei;Shionoya, Mitsuhiko
阴离子的识别和结合在ATP代谢和跨膜转运等生物学过程中起着重要的作用，从而调节细胞内的渗透压。此外，阴离子识别已成为超分子化学的一个主要领域，如选择性阴离子传感器和阴离子模板分子结构等系统。[1]In[2]金属离子通常充当有机构建块的自发但定向组装的胶。[3]在某些情况下，金属中心的配位不稳定位点提供了通过配体交换反应直接结合客体物质的平台。[1]相比之下，带正电的金属配合物也可以通过纯粹的静电相互作用与阴离子物种相互作用。因此，这种金属中心在具有中空空间的分子组件内的精确定位将允许与阴离子客体分子的特定吸引相互作用。在本文提出的系统中，两个PdII离子由四个双（单齿）配体结合，得到稳定的squareplanar配合物的d8 PdII离子。两个PdII中心间隔1.7 nm，并通过刚性香蕉形配体直接连接，从而允许该构建体通过库仑相互作用定量结合一个双阴离子客体（图1a）。[4]美国
Anion recognition and binding play an important role in biological processes, such as ATP metabolism and transmembrane transport of anions to regulate osmotic pressure in the cell. Furthermore, anion recognition has emerged to be a major area of supramolecular chemistry, as exemplified by systems such as selective anion sensors and anion-templated molecular architectures.[1]In supramolecular assemblies such as nanoscopic cages and capsules,[2] metal ions often act as glue for the spontaneous but directed assembly of organic building blocks.[3] In some cases, coordinatively labile sites of metal centers provide a platform for direct binding to guest species through ligand-exchange reactions.[1] In contrast, positively charged metal complexes can also interact with anionic species through pure electrostatic interactions. Accordingly, the precise positioning of such metal centers within molecular assemblies that have a hollow space would allow for specific attractive interactions with anionic guest molecules. In the system presented herein, two PdII ions are bound by four bis (monodentate) ligands to give stable squareplanar complexes of the d8 PdII ions. The two PdII centers are spaced 1.7 nm apart and are directly linked by the rigid, banana-shaped ligands, thus allowing this construct to quantitatively bind one dianionic guest by coulombic interactions (Figure 1 a).[4]