Actinyl peroxide nanospheres
Actinyl peroxide nanospheres
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DOI：
10.1002/anie.200462445
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发表时间：
2005-01-01
影响因子：
16.6
通讯作者：
Soderholm, L
中科院分区：
文献类型：
--
作者：
Burns, PC;Kubatko, KA;Soderholm, L
安吉街2173号2005，117，2173-2177 DOI：10.1002/ange. 200462445 2005 Wiley-VCH Verlag GmbH & Co. KGaA，魏因海姆的数据基于主族元素，最值得注意的是C60（巴克敏斯特富勒烯）[1]和过渡金属氧化物簇，包括建立在WO、MoO和NbO框架上的各种聚氧乙烯酸盐。[2]基于这些系统的研究已经对纳米级的电子，磁性和结构特性产生了新的见解，并提供了许多具有重要应用的新型材料的例子。[3，4]纳米颗粒在许多环境系统中也相当重要，因为它们通常在低温下形成，可以影响地质流体中重金属和放射性核素的运输，并且足够小，其特性通常取决于颗粒大小。[5]在这里，我们报告的合成和表征的一个新的家庭的自组装纳米球从锕系离子（Ac）和他们的持久性作为稳定的实体在碱性溶液中。这些纳米球具有诸如[K16（H2O）2-（UO 2）（O2）2（H2O）2 {（UO 2）（O2）1.5} 28] 14 η和[Li 6（H2O）8 NpO 2-（H2O）4 {（NpO 2）（O2）（OH）} 24] 20 η的组成，并且由线性过氧化放线菌酰结构单元组成。这个新的过氧化放线酰化合物家族的铀酰和镎酰成员在258 ℃下从UVI和NpV离子的碱性过氧化物溶液中沉淀出来，大约需要7天或更长时间。图la-c显示了本文关注的四种示例性过氧化放线菌素纳米球的结构。它们的分子单元由24、28或32个过氧化铀酰多面体（U-24、U-28和U-32）或24个过氧化镎酰多面体（Np-24）组成。[6]纳米球的直径约为16.4、17.7和18.6（在键合氧原子的中心之间测量）。纳米球由两种类型的过氧化放线菌素多面体组成：U-24、U-32和Np-24含有拓扑结构相同的[（AcO 2）（O2 2 2 H2）2（OH）2]六方双锥，其中放线菌素离子的氧原子构成双锥的顶点，过氧化物基团形成多面体的两个赤道边缘（图1a、c）。U-28只含有[（AcO 2）（O2 2 2 O）3]六方双锥，其中多面体的三个赤道边缘是过氧化物基团（图1b）。在所有情况下，六方双锥都是通过与相邻的多面体共享三条赤道边来连接的。U-24、Np-24和U-32中的两个共享边对应于过氧化物基团，第三个边由两个羟基组成，而U-28中的所有三个共享边都是过氧化物基团。纳米球的外表面是锕基离子的氧原子，每个AcVIO键对应大约1.7个价单位;[7]因此，这些氧原子只能形成弱键。与过氧化物基团相关的多面体边缘的缩短有利于形成纳米球，而不是正常连接成片或链。图2显示了U-24、U-32和Np-24中多面体连接成四元环的情况。四元环内的每个共享边缘是具有大约1.45的长度的过氧化物基团，而由两个过氧化物基团中的每一个的一个氧原子限定的边缘具有大约2.8的长度。将四个多面体连接成一个环需要使多面体倾斜，其中锕基离子指向位于四个共面AcVI阳离子下方约3.5的公共点（图2c）。在U-24和Np-24中发现的纳米球是由八个拓扑和化学上相同的多面体四元环连接而成的（图2d）。
2173 Angew. Chem. 2005, 117, 2173–2177 DOI: 10.1002/ange. 200462445 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim date are based on main-group elements, most notably C60 (buckminsterfullerene)[1] and transition-metal oxide clusters, including a wide variety of polyoxometalates built on WO, MoO, and NbO frameworks.[2] Studies based on these systems have resulted in new insight into electronic, magnetic, and structural properties at the nanoscale and provide numerous examples of novel materials with important applications.[3, 4] Nanoparticles are also of considerable importance in many environmental systems as they often form at low temperatures, can impact the transport of heavy metals and radionuclides in geologic fluids, and are small enough that their properties are often particle-size dependent.[5] Herein, we report the synthesis and characterization of a new family of self-assembling nanospheres from actinide ions (Ac) and their persistence as stable entities in alkaline solutions. These nanospheres have compositions such as [K16 (H2O) 2-(UO2)(O2) 2 (H2O) 2 {(UO2)(O2) 1.5} 28] 14À and [Li6 (H2O) 8NpO2-(H2O) 4 {(NpO2)(O2)(OH)} 24] 20À and are comprised of linear actinyl peroxide building blocks. The uranyl and neptunyl members of this new family of actinyl peroxide compounds precipitated from alkaline peroxide solutions of UVI and NpV ions at 258C after approximately seven days or longer. Figure 1a–c shows the structures of four exemplary actinyl peroxide nanospheres that are the focus herein. Their molecular units are composed of 24, 28, or 32 uranyl peroxide polyhedra (U-24, U-28, and U-32) or 24 neptunyl peroxide polyhedra (Np-24).[6] The nanospheres are approximately 16.4, 17.7, and 18.6 in diameter (as measured between the centers of bonding oxygen atoms). The nanospheres are composed of two types of actinyl peroxide polyhedra: U-24, U-32, and Np-24 contain topologically identical [(AcO2)(O2 2À) 2 (OH) 2] hexagonal bipyramids, in which the oxygen atoms of the actinyl ions constitute the apices of the bipyramids and the peroxide groups form two of the equatorial edges of the polyhedra (Figure 1a, c). U-28 contains only [(AcO2)(O2 2À) 3] hexagonal bipyramids, in which three equatorial edges of the polyhedra are peroxide groups (Figure 1b). In all cases, the hexagonal bipyramids are linked by sharing three of their equatorial edges with adjacent polyhedra. Two of the shared edges in U-24, Np-24, and U-32 correspond to peroxide groups and the third edge consists of two hydroxy groups, whereas all three shared edges in U-28 are peroxide groups. The outer surfaces of the nanospheres are the oxygen atoms of the actinyl ions and each AcVIÀO bond corresponds to approximately 1.7 valence units;[7] therefore, these oxygen atoms can form only weak bonds. The shortening of the polyhedra edges associated with peroxide groups favors formation of nanospheres over the normal linkage into sheets or chains. Figure 2 illustrates the linkage of the polyhedra into four-membered rings in U-24, U-32, and Np-24. Each shared edge within the four-membered ring is a peroxide group with approximate lengths of 1.45, whereas the edge defined by one oxygen atom of each of the two peroxide groups has a length of approximately 2.8. The linkage of four polyhedra into a ring requires a tilting of the polyhedra with the actinyl ions directed towards a common point located approximately 3.5 below the four coplanar AcVI cations (Figure 2c). The nanospheres found in U-24 and Np-24 result from the linkage of eight topologically and chemically identical four-membered rings of polyhedra (Figure 2 d).U-28 …