Transition Metal Clusters as Single-Molecule Magnets

技术总结建议的研究是在单分子磁体(SMM)领域，由DMR固态和材料化学计划支持。SMM是一种可以作为纳米磁体的分子，它们将分子化学的所有优点带到了纳米磁性领域，包括溶解性、结晶性、单分散性和有机配体的壳层，有机配体的修饰可以微调许多这些性质和其他性质，如氧化还原电位。拟议的工作将推动该领域沿着多个前沿主要朝着新的方向前进，包括：(I)通过适当设计的桥联配体形成超分子聚集体的共价键，这些超分子聚集体仍然是分子的，并且表现出弱的SMM间交换相互作用，从而引入量子效应，例如组成SMM单元的叠加态和纠缠；(Ii)使用光致变色有机桥联配体来允许开发方法来控制超分子聚集体中不同SMM之间的相互作用的光开关，从而开启和关闭导致它们量子纠缠和叠加态的量子力学耦合；这是将SMM用作量子计算和相关专业应用中的量子比特(量子比特)的先决条件；(Iii)利用后来的稀土离子的高磁各向异性，合成具有比目前可用的更高工作温度的新的混合金属3D-4f SMM；以及(Iv)启动一个新的方向，涉及合成在结构上类似于混合金属锰酸盐和铁氧体多铁氧化物的式MMnO_3和MFeO_3(M=稀土或主族金属)的‘分子多铁氧体’；这些三元氧化物同时具有磁性和铁电有序，其目标是开发方法来访问也表现出这两种类型的性质的分子。为了实现这些目标，将开发一些新的合成方法，其中一些方法涉及使用微波反应堆的高能条件。非技术性和磁性材料在美国是每年数十亿美元的产业。目前含有磁铁的设备小型化的趋势使得开发越来越小的磁铁变得至关重要。这项拟议的研究是在单分子磁体(SMM)领域进行的；单分子磁体是起纳米级磁体作用的单个分子，比传统磁性材料的磁体小得多。这项拟议的研究有多个目标，包括改善已知SMM的性能，开发将其中两个或更多SMM连接在一起的方法，以引入对SMM在量子计算等新技术中的潜在使用至关重要的某些效应，以及使SMM还具有第二个重要属性，使其能够用于材料科学的其他领域。他和他的团队还将积极参与许多外展、教育和国际活动，这些活动旨在最大限度地扩大他的研究项目的更广泛影响。他将支持每年在佛罗里达州盖恩斯维尔购物中心举办的针对K-12学生、他们的教师和家长以及当地社区和媒体的年度化学日的规划和执行；他将在佛罗里达大学S学生科学培训计划下，每年接待一名佛罗里达州高中生进行暑期研究；他将继续组织佛罗里达州13所高等教育机构的年度佛罗里达无机物和材料研讨会学生会议，这些机构包括授予博士学位的大学、本科学院和社区学院；他还将共同组织两个两年一度的国际研讨会，即分子和纳米尺度磁性当前趋势研讨会(2014年)和北美-希腊-塞浦路斯顺磁材料研讨会(2013年和2015年)，这两个研讨会都强调学生和博士后的口头陈述。P.I.还将继续与几个国家和国际组织合作，向物理学家提供研究样本，用于研究量子和其他性质，并使用他们无法获得的技术研究合成化学家送来的化合物。

TECHNICAL SUMMARYThe proposed research, supported by the DMR Solid State and Materials Chemistry program, is in the field of single-molecule magnets (SMMs). SMMs are molecules that can function as nanoscale magnets, and they bring all the advantages of molecular chemistry to the field of nanomagnetism, including solubility, crystallinity, monodispersity, and a shell of organic ligands whose modification can fine-tune many of these properties and others such as redox potentials. The proposed work will push the area forward along multiple fronts in mainly new directions, including: (i) the covalent linkage of multiple SMMs by suitably designed bridging ligands into supramolecular aggregates that are still molecular and exhibit weak inter-SMM exchange interactions that introduce quantum effects such as superposition states and entanglement of the constituent SMM units; (ii) the use of photochromic organic-bridging ligands to allow development of methods for controlled photo-switching ON and OFF of the interactions between separate SMMs in supramolecular aggregates, thus switching ON and OFF the quantum mechanical coupling that results in their quantum entanglement and superposition states; this is an ability that is a pre-requisite for the use of SMMs as qubits (quantum bits) in quantum computing and related specialized applications; (iii) the synthesis of new mixed-metal 3d-4f SMMs with higher operating temperatures than are currently available, taking advantage of the high magnetoanisotropy of the later lanthanide ions; and (iv) the initiation of a novel direction involving the synthesis of 'molecular multiferroics' that are structurally analogous to mixed-metal manganite and ferrite multiferroic oxides of formula MMnO3 and MFeO3 (M = a lanthanide or main-group metal); these ternary oxides possess both magnetic and ferroelectric order, and the objective is to develop methods to access molecules that also exhibit both of these types of properties. A number of new synthetic methodologies, some involving higher-energy conditions using microwave reactors, will be developed to accomplish these objectives.NON-TECHNICAL SUMMARYMagnetic materials are a multi-billion dollar annual industry in the USA. Current trends in miniaturization of devices containing magnets have made the development of smaller and smaller magnets essential. The proposed research is in the area of single-molecule magnets (SMMs); these are individual molecules that function as nanoscale magnets that are much smaller than those of traditional magnetic materials. The proposed research has multiple objectives, including improving the properties of known SMMs, developing methods to link two or more of them together to introduce certain effects crucial to the potential use of SMMs in new technologies such as quantum computing, and making SMMs that also possess a second important property that will allow them to be employed in other areas of materials science. The P.I. and his group will also be active in many outreach, education and international activities designed to maximize the broader impacts of his research program. He will support the planning and execution of the annual Chemistry Day at the Mall in Gainesville, FL, targeted at K-12 students, their teachers and parents, and the local community and media; he will host each year a Florida high-school student for summer research under the University of Florida?s Student Science Training Program; he will continue to organize the annual Florida Inorganic and Materials Symposium student meetings of 13 Florida higher education institutions spanning PhD granting universities, undergraduate colleges, and community colleges; and he will co-organize two biennial international workshops, the Current Trends in Molecular and Nanoscale Magnetism workshop (2014), and the North America-Greece-Cyprus Workshop on Paramagnetic Materials (2013, 2015), both of which emphasize oral presentations from students and postdoctorals. The P.I. will also continue collaborating with several national and international groups, providing research samples to physicists for study of quantum and other properties, and studying compounds sent by synthetic chemists using techniques not available to them.