Derivatized and Nanoscale Polyoxometalate Cluster Anions

乔治城大学化学系Michael T. Pope博士在无机、生物无机和有机金属化学项目的支持下，研究多金属酸氧化合物的化学性质。本研究旨在开发坚固的、水稳定的、功能化的有机衍生物：(a)含有10-30个钨原子和一到几种其他原子类型的多钨酸盐阴离子，可以用作进一步衍生化的位点；(b)含有100多个金属原子的纳米尺度的大质量、可溶的离散多氧阴离子。在铑上衍生含铑(a)型络合物的能力将用于将多金属氧酸盐偶联到核糖体上，以进行x射线数据的分相。额外的(a)型物种将用多个位点进行衍生化。这些物质可以用作载体，将催化活性的多氧阴离子附着在聚合物底物上，用于选择性电子密度成像和其他应用。(b)型配合物的典型例子是一个76-阴离子，包含12个As， 16个Ln， 148个W和524个O原子以及36个水分子。这种阴离子是水溶性的，并已被晶体学表征。合成策略将被设计为该物种的类似物，其中As被其他15族原子取代，以及含有各种镧系元素的类似物。将设计更大的集群的准备工作。将研究这些大阴离子在溶液中的水解稳定性、结构、电化学和其他性质。将设计方法将这些簇阴离子偶联到设计的、扩展的组装中。多金属氧酸盐是由金属和氧原子组成的大离子。它们之所以令人感兴趣，是因为它们完全是无机的，因此在许多条件下应该是相当健壮的。本研究将探讨这两类离子的化学性质。第一种含有10-30个金属原子，其中心可以与其他化学物质相连。第二类是由非常大的离子组成，含有数百个原子，是纳米级的。这两类化合物都是不寻常的，因为它们溶于水且在水中稳定。它们在离子交换和主/客体材料、催化剂、导电和磁性材料以及显示器件等方面具有潜在的应用前景。

Dr Michael T. Pope, Chemistry Department, Georgetown University, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program, to investigate the chemistry of polyoxometalate species. This research is directed towards developing robust, water-stable, functionalized organic derivatives of (a) polytungstate anions containing 10-30 tungsten atoms and one to several other atom types that can be used as sites of further derivatization and (b) massive, soluble discrete polyoxoanions of nanoscale dimensions that contain 100+ metal atoms. The ability to derivatize rhodium containing type (a) complexes at the rhodium will be used to couple the polyoxometalate to ribosomes for phasing of x-ray data. Additional type (a) species will be prepared with multiple sites for derivatization. These species can be utilized for supporting agents to attach catalytically active polyoxoanions to polymer substrates, for selective electron-density imaging, and other applications. Type (b) complexes are exemplified by a 76- anion containing 12 As, 16 Ln, 148 W, and 524 O atoms plus 36 water molecules. This anion is water soluble and has been crystallographically characterized. Synthetic strategies will be designed for analogues of this species in which As is substituted by other group 15 atoms and for those that contain a variety of lanthanides. The preparation of even larger clusters will be devised. The hydrolytic stability, structures, electrochemistry and other properties will be investigated in solution for these large anions. Methods will be designed to couple these clusters anions into designed, extended assemblies. The polyoxometalates are a large ions composed of metal and oxygen atoms. They are of interest because they are wholly inorganic, and thus should be quite robust under many conditions. This investigation will explore the chemistry of two classes of these ions. The first contains 10-30 metal atoms and has centers that can be linked to other chemical species. The second class is composed of very massive ions that contain hundreds of atoms and are nano-sized. Both classes are unusual for because they dissolve in and are stable in water. They have potential applications as ion-exchange and host/guest materials, catalysts, conducting and magnetic materials, and display devices.