Directed Assembly of Molecular Cluster Magnets

分子簇磁体的定向组装

• 批准号: 0617063
• 负责人: Jeffrey Long
• 金额: --
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-15 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0617063&HistoricalAwards=false
• 关键词: Directed; Assembly; Molecular; Cluster; Magnets

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program to Professor Jeffrey R. Long of the University of California at Berkeley is to develop general strategies for the synthesis of metallocyanide coordination clusters as single-molecule magnets (SMMs) that have potential in high-density information storage and quantum computing. The ability to utilize organic blocking ligands in directing the formation of specific metallocyanide cluster geometries will be extended to the synthesis of higher-nuclearity species, such as edge-centered cubic [(L-fac)8(Leq) 12M12M'8(CN)24]n+ and double-cube [(L-fac)14M7M'8(CN)24]n+ clusters. The substitution of appropriate paramagnetic metal ions into these clusters has led to ground states of up to S = 18, and new species with spins as high as S = 32 will be targeted. Incorporation of metal ions possessing a large axial zero-field splitting into such structures will be pursued as a means of generating the magnetic anisotropy requisite of a single-molecule magnet. Additional work will focus on further enhancing magnetic anisotropy through the incorporation of third-row transition metal centers bearing orbital angular momentum, such as Ta(III), W(IV), Re(III), Re(V), and Os(IV). Moreover, the use of heavy donor atom ligands will be tested as a means of further increasing the single-ion anisotropy associated with cluster building units. Routes to linear clusters with parallel alignment of the individual ion anisotropy axes are proposed, as is a method for breaking the symmetry in high-nuclearity cubic species via heterometal substitution. A magnetochemical series in which linear bridging ligands are ordered according to their magnetic exchange coupling ability, will be established as a means of evaluating replacement ligands for cyanide with stronger magnetic coupling. In addition, certain of these ligands may facilitate electron transfer to an extent that enables the synthesis of mixed-valent, ligand-bridged clusters with well-isolated high-spin ground states arising via a double exchange mechanism. The broader impacts of this research include a legacy of synthetic techniques, the creation of new materials of potential technological importance, and the education and training of postdoctoral, graduate, and undergraduate students in the synthesis and characterization of inorganic materials. As a related educational activity, the PI will take the lead in creating a materials chemistry major within the Dept. of Chemistry at UC Berkeley.

该奖项授予加州大学伯克利分校的Jeffrey R.Long教授，该奖项旨在开发合成金属氰化物配位团簇的一般策略，作为单分子磁体(SMM)，在高密度信息存储和量子计算方面具有潜力。利用有机封闭配体来指导形成特定的金属氰化物簇合物的能力将扩展到高核度物种的合成，如边心立方[(L-FAC)8(LEQ)12M12M‘8(CN)24]n+和双立方体[(L-FAC)14M7M’8(CN)24]n+簇合物。将适当的顺磁性金属离子替换到这些团簇中，已经导致了高达S=18的基态，并且具有高达S=32的自旋的新物种将成为目标。将具有较大轴向零场分裂的金属离子结合到这样的结构中，作为产生单分子磁体所需的磁各向异性的手段。其他工作将集中在通过引入带有轨道角动量的第三排过渡金属中心，如Ta(III)、W(IV)、Re(III)、Re(V)和Os(IV)来进一步增强磁各向异性。此外，将测试重施主原子配体的使用，作为进一步增加与团簇构建单元相关的单离子各向异性的手段。提出了各离子各向异性轴平行排列的线状团簇的途径，以及通过异金属取代打破高核度立方物种对称性的方法。根据线性桥联配体的磁交换耦合能力对其进行排序的磁性化学系列将被建立为评估具有更强磁性耦合的氰化物的替代配体的手段。此外，这些配体中的某些可以促进电子转移到一定程度，使得能够合成混合价、配体桥联的簇合物，这些簇合物具有良好的隔离的高自旋基态，通过双交换机制产生。这项研究的更广泛的影响包括合成技术的遗产，创造具有潜在技术重要性的新材料，以及在无机材料的合成和表征方面对博士后、研究生和本科生进行教育和培训。作为一项相关的教育活动，PI将在系内率先创建材料化学专业。加州大学伯克利分校化学系。