Transition Metal Clusters as Single-Molecule Magnets

技术摘要：拟议的研究，由DMR固态和材料化学计划支持，是在单分子磁体（SMMs）领域。smm是一种可以作为纳米级磁铁的分子，它们将分子化学的所有优点带到纳米磁学领域，包括溶解度、结晶性、单分散性，以及有机配体的外壳，其修饰可以微调许多这些性质和其他性质，如氧化还原电位。所提出的工作将推动该领域沿着多个前沿向前发展，主要是新的方向，包括：(i)通过适当设计的桥接配体将多个SMM的共价键连接到仍然是分子的超分子聚集体中，并表现出弱的SMM间交换相互作用，引入量子效应，如SMM组成单元的叠加态和纠缠；（ii）使用光致变色有机桥接配体来开发控制超分子聚集体中单个smm之间相互作用的光开关方法，从而打开和关闭导致量子纠缠和叠加态的量子力学耦合；这是在量子计算和相关专业应用中使用smm作为量子比特（量子位）的先决条件；（iii）利用后期镧系离子的高磁各向异性，合成具有比现有操作温度更高的新型混合金属3d-4f smm；（iv）开创了一个新方向，涉及合成“分子多铁氧体”，其结构类似于分子式MMnO3和MFeO3 （M =镧系元素或主族金属）的混合金属锰铁矿和铁氧体多铁氧体氧化物；这些三元氧化物同时具有磁性和铁电性，目标是开发方法来获得同时具有这两种性质的分子。将开发一些新的合成方法，其中一些涉及使用微波反应堆的高能条件，以实现这些目标。磁性材料在美国是一个年产值数十亿美元的产业。目前磁铁器件小型化的趋势使得越来越小的磁铁的发展变得至关重要。提出的研究方向是单分子磁体（SMMs）；这些单个分子的功能相当于纳米级磁铁，比传统磁性材料小得多。拟议的研究有多个目标，包括改善已知smm的特性，开发将两个或多个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还具有第二个重要特性，使其能够用于材料科学的其他领域。私家侦探和他的团队还将积极参与许多外联、教育和国际活动，旨在最大限度地扩大他的研究项目的广泛影响。他将支持在佛罗里达州盖恩斯维尔的购物中心策划和执行年度化学日，目标是K-12学生，他们的老师和家长，以及当地社区和媒体；他将每年接待一名佛罗里达高中学生到佛罗里达大学做暑期研究？学生科学训练计划；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和材料研讨会学生会议，涵盖博士学位授予大学、本科学院和社区学院；他将共同组织两个两年一次的国际研讨会，分子和纳米磁性的当前趋势研讨会（2014年）和北美-希腊-塞浦路斯顺磁性材料研讨会（2013年，2015年），这两个研讨会都强调学生和博士后的口头报告。私家侦探还将继续与几个国内和国际组织合作，为物理学家提供研究样本，以研究量子和其他性质，并研究合成化学家送来的化合物，使用他们无法使用的技术。

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.