Transition Metal Clusters as Single-Molecule Magnets

University Of Florida, Gainesville FL

Investigators

Abstract

TECHNICAL SUMMARY The 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 SUMMARY Magnetic 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.