Directed Assembly of Metal-Cyanide Cluster Magnets

这个奖项给加州大学伯克利分校支持杰弗里教授的工作。Long，化学系，旨在合成可用作单分子磁体的高核过渡金属氰化物簇。 该项目由化学系的无机，生物无机和有机化学计划以及材料科学系的固态化学计划提供支持。将制备一系列具有不同金属成分的立方簇合物。 簇的几何形状是基于从普鲁士蓝型结构切除的单个笼，并且由金属原子的立方体组成，每个边缘由线性氰化物桥跨越，每个角由三齿tacn（1，4，7-三氮杂环壬烷）配体封端。 目前已知该簇的两种变体，一种含有八个钴原子，另一种含有四个铬原子和四个钴原子。 顺磁性金属中心将用于制备该系列的其他成员，从而产生一系列具有总基态自旋状态的化合物，其范围从S=0至S=10，为偶数整数值。 也将合成更大的簇以实现更高的总自旋状态。 这可以通过从反应物分子之一去除封端配体以促进簇生长来实现。 将制备一系列具有边桥立方结构的相关化合物;预计总自旋值高达S=26。 一些不太对称的长双立方体集群也将被追求，以及一个铁磁耦合的五角双锥集群与S=18基态。在本研究中合成的团簇将表现出轴向磁各向异性以及整体磁各向异性。 将使用可变温度磁化率测量以及必要时与数据存储相关的物理参数来检查磁行为。团簇磁体在高密度数据存储和磁化量子隧穿等现象的研究中具有潜在的应用。这些化合物的结构和磁交换途径比以前研究的一些系统要简单一些，因此预计确定重要的设计特征将更加简单。参与该项目的学生将学习先进的合成方法，并在与纳米科学和工程相关的化学，材料和物理学方面拥有跨学科的经验。

This award to the University of California at Berkeley supports the work of Professor Jeffrey R. Long, Department of Chemistry, aimed at the synthesis of high-nuclearity transition-metal cyanide clusters that can function as single-molecule magnets. The project is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry program in the Chemistry Division and by the Solid State Chemistry program in the Division of Materials Science. A series of cubic clusters with varying metal constituents will be prepared. The cluster geometry is based on a single cage excised from a Prussian Blue type structure and consists of a cube of metal atoms with each edge spanned by a linear cyanide bridge and each corner capped by a tridentate tacn (1,4,7-triazacyclononane) ligand. Two variants of the cluster are presently known, one with eight cobalt atoms, and one with four chromium and four cobalt atoms. Paramagnetic metal centers will be used to prepare additional members of the series, giving rise to a series of compounds with total ground state spin states ranging from S=0 to S=10, in even integral values. Larger clusters will also be synthesized in order to achieve higher total spin states. This can be accomplished by removing the capping ligand from one of the reactant molecules to promote cluster growth. A related series of compounds with an edge-bridged cubic structure will be prepared; total spin values as high as S=26 are expected. Some less symmetric prolate double-cube clusters will also be pursued, as well as a ferromagnetically coupled pentagonal bipyramidal cluster with an S=18 ground state. The clusters synthesized in this research will exhibit axial magnetic anisotropy as well as overall magnetic anisotropy. Magnetic behavior will be examined using variable temperature susceptibility measurements and, when warranted, physical parameters relevant to data storage. Cluster magnets have potential applications in high-density data storage and for investigation of phenomena such as quantum tunneling of magnetization. These compounds have somewhat simpler structures and magnetic exchange pathways than some systems that have been studied previously, and so it is anticipated that determining important design features will be more straightforward. Students involved in this project will learn advanced synthesis methods and have an interdisciplinary experience in chemistry, materials, and physics relevant to nanoscience and engineering.