Molecular Magnets: From Cages to Supramolecular Assemblies

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Chemistry


Magnetic Materials are employed in an enormous range of applications in modern society, from information storage in computers, refrigeration in security and astronomical instrumentation, biocompatible agents for use as both contrast and polarizing agents in magnetic resonance imaging (MRI) and diagnosis, and as agents for magnetic hyperthermic treatments. Academically, molecule-based magnets are also studied intensively with regard to their important fundamental chemistry and physics, since they have the potential to be exploited in nanoscale electronics devices, as beautifully demonstrated recently by the construction of single-molecule spintronic devices (spin valves and transistors). Molecule-based materials offer the great advantage of being designable and manipulable by synthetic chemistry. That is, they can be constructed atom by atom, molecule by molecule with the unparalled advantages of being soluble, monodisperse in size, shape and physical properties, and tuneable at the atomic scale. Indeed, this "bottom-up" research vision is not restricted to academia - IBM recently reported information storage in surface-isolated (2x6) arrays of Fe atoms at liquid He temperatures and are actively investigating spintronics and data storage with a view to the ultimate miniaturisation of such technologies. However, before any molecule or molecule-based material can have commercial application or value, the fundamental and intrinsic relationship between structure and magnetic behaviour must be understood. This requires the chemist to design and construct familes of related complexes, characterise them structurally and magnetically, and through extensive collaboration with a network of world-class condensed matter physicists and theoreticians, understand their underlying physical properties. The current proposal directly addresses these fundamental questions through the controlled aggregation and organisation of molecular magnets into designed 0-3D architectures in the solid state. Specifically it applies the fundamental principles underpinning supramolecular chemistry to assemble single-molecule magnets into novel topologies by taking advantage of simple coordination-driven self-assembly processes. We will employ molecular magnets as building blocks for the formation of supramolecular assemblies and coordination polymers in which the spin dynamics of the molecular building blocks are modulated through the attachment of, and interaction with, other paramagnetic moieties. In order to achieve this we will: design and build a range of metalloligands, ranging from simple isotropic molecules to more complex and exotic anisotropic molecules and attach them to pre-made SMMs; construct hybrid magnetic materials from SMMs and cyanometalate building blocks; design and synthesise dual-functioning ligands which are capable of directing the formation of SMMs and simultaneously linking them into higher order (O-3D) materials; and characterise all materials, structurally and magnetically, through a battery of techniques.

Planned Impact

Magnetic materials underpin modern society, finding use in an enormous variety of applications that impact our daily lives: data storage on desktop and laptop computers, smart phones and i-pads; MRI scanners in hospitals and the treatment of cancer via thermotherapy; cooling devices employed in security instrumentation and astronomical radiation detectors. These are £multi-billion per annum industries with clear benefits to the UK economy. Future commercial exploitation is potentially enormous with technological improvements likely adding significant monetary value. Our "bottom-up" approach to making, characterising and exploiting magnetic materials, aligned with EPSRC Grand Challenges and UK priority areas of funding, offers new molecule-based technologies with potentially transformative impact upon all of these areas. If novel Intellectual Property arises, our Business Development Executive will provide advice on potential avenues for industrial partnership, with existing University partners canvassed to assess interest and identify routes for future collaboration, exploitation and application.

Policymakers and the Public
Non-academics, administrators and policymakers in the UK and EU will benefit from the knowledge that the modern applicable science technologies they are reliant upon every day - and perhaps take for granted - are dependent on fundamental academic science. The link between, for example, data storage, security instrumentation, refrigeration, and molecular chemistry and physics is perhaps not an obvious one for policymakers. We expect world-leading academic outputs that will shape future directions in the field. By-so-doing we aim to influence UK politicians and decision makers, who we come into contact with at 'Science in the Parliament' and related events, that useful technologies have their foundations in academic chemistry and physics, highlighting the importance of supporting such fundamental research. The diverse public engagement and outreach package targeting UK HEIs, schools and the wider public will ensure our fundamentals through to application message clarifies the importance of lab-based chemistry and physics on modern information technology and instrumentation. Computers, gaming, smart phones and Outer Space are just some of the popularity hooks that will drive public interest.

Education, Training and Mobility
The PI is fully committed to providing a first class environment for training and career development. EKB collaborates with an international network of world-class scientists studying molecular magnets, providing access to every conceivable technique required for studying such materials. The skills gain will therefore be enormous. All young researchers in the Brechin group are trained to think and work in an interdisciplinary manner. Visits to our overseas collaborators (Hill (EPR) and Evangelisti (heat capacity)) will serve to further enhance their expertise and contact base that will be invaluable in any technical or intellectually challenging line of work in the future. The University of Edinburgh is a recognised centre of excellence for the provision of transferable skills training, and the researcher(s) will benefit from the vast range of training opportunities available to them through the Institute of Academic Develoment. This encompasses research communication and presentation through to publicity and media training and business methodology and entrepreneurship; initiatives which match the aims of RCUK.


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Coletta M (2016) Bis-Calix[4]arenes: From Ligand Design to the Directed Assembly of a Metal-Organic Trigonal Antiprism. in Chemistry (Weinheim an der Bergstrasse, Germany)

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Frost JM (2014) A truncated [Mn(III)12] tetrahedron from oxime-based [Mn(III)3O] building blocks. in Dalton transactions (Cambridge, England : 2003)

Description Magnetic materials are ubiquitous in modern life, used in technologies as diverse as computers, smart phones and tablets, medical equipment, hybrid cars, wind turbines, security and communications equipment. They are also of enormous importance in cutting edge academic chemistry, physics and materials science research, since molecules proffer better, faster, smaller, cleaner, greener, cheaper, more controllable alternatives to traditional solid state materials, with potentially transformative impact upon information storage, quantum computation and spintronics, industries worth €billions to the UK/EU economy, where advances in fundamental science can have transformative technological and economic impact. Magnetic molecules exhibit a range of beautiful low temperature physics from spin frustrated molecules and molecules displaying remarkably long quantum coherence times, to anisotropic metal cages behaving like nanoscale magnets. For example, spins confined to equilateral triangles or pentagons in Platonic or Archimedean solids (e.g. [Fe30]), or in odd-numbered wheels (e.g. [CrIII7MII]), give rise to highly unusual physics. In Single-Molecule Magnets (SMMs) molecular structure and symmetry defines and controls exchange interactions, anisotropy and the nature of magnetisation relaxation processes. In molecular spin qubits, proposed logic units of quantum computers, molecular design must result in a molecule retaining its quantum state memory for a time period long enough to allow quantum operations to be performed.
Exploitation Route We have applied the fundamental principles of metallosupramolecular chemistry to assemble novel capsule-based molecular magnets. While the last two decades has seen an explosion in coordination capsules, almost all utilise diamagnetic metal ions (most commonly Pd2+, Pt2+, Fe2+, Ru2+, Ga3+). Even with the few paramagnetic examples reported (most commonly Co2+), the magnetic exchange has rarely been studied, while guest-induced magnetic modulation has never been studied in detail. The closest analogy comes in the chemistry of porous coordination polymers, where the magnetic behaviour of Prussian Blues and metal formates, for example, are modified through encapsulation of different solvents and gases. It is therefore easy to envisage how the non-covalent manipulation of molecular magnetic properties via host-guest interactions could be exploited for a raft of potential applications from switchable SMMs to quantum information processing (QIP). At this stage we foresee that the development of a fundamental understanding of how the magnetic properties of capsules constructed from paramagnetic metal ions vary in relation to overall structure, symmetry and binding of both diamagnetic and paramagnetic guest species will be the best way to measure success. Such an understanding, of course, will be continuously fed into the design of species with improved properties, with the long term goal of realising functional devices.
Sectors Chemicals,Digital/Communication/Information Technologies (including Software),Electronics,Energy