Non-classical paramagnetic susceptibility and anisotropy in lanthanide coordination complexes: a combined experimental and theoretical study

Rare earth elements are used widely in society and industry in the 21st century. Even your mobile phone contains up to 9 different rare earth elements, harnessing their unique magnetic and optical properties. Advances in the application of these properties requires that we understand better the physicochemical origins of their behaviour. A key part of this process is to develop new theories that test our understanding, and guide us in the design of new chemical applications.

Of particular importance is the magnetic behaviour of the rare earth elements in their chemical compounds, and the ramifications of the directional dependence of the 'paramagnetism' that arises from unpaired electron density. This behaviour has important consequences not only in the design of new magnetic materials, but also in their use in magnetic resonance imaging (MRI) where they have been used since 1988 as contrast agents to assist in clinical diagnosis of disease. For example, paramagnetic lanthanide coordination complexes are being created as proton chemical shift magnetic resonance probes, in a radical change in imaging technology that directly relates to the importance of imaging technologies in healthcare.

This multidisciplinary project brings together three teams of scientists with complementary expertise in Durham, Manchester and Southampton to develop and test new theoretical and computational approaches that will promote a better understanding of the magnetic properties of new series of rare earth chemical compounds that are directly relevant to their application in magnetism and their scope for use in MRI.

The project relates to the EPSRC Physical Science capability theme, notably in the direct involvement with synthetic coordination/supramolecular chemistry. Industry in the UK has strategic interests in developing magnet technology (Oxford Instruments) and in promoting new chemical probe applications (e.g. GE-Amersham/ GSK). These companies will be made aware of the scientific advances defined in this work, either via academic channels of conference dissemination and primary publications, or by direct contact, once commercial confidentiality is properly protected. These cases will be handled by the University's Business and Innovations Service: n.b. Durham Chemistry was placed top for Impact in REF 2014, and the PI was responsible for one of the 4* case studies.

The PI and Co-I's will continue to cooperate with research groups around Europe (e.g. PI via participation in the European Society for Molecular Imaging; co-Is via their involvement with the RSC ESR Group as Secretary and as co-Director of the EPSRC National EPR Facility) exchanging information, publicising key advances and organising short-term scientific missions to selected research groups (e.g. C Faber/Munster; S. Aime/Torino), aided by the annual meetings of these cohorts.

Nationally, the background to this project links to the EPSRC Challenge theme, Healthcare Technologies (involving Medical Imaging and Biological Chemistry), creating impact by improved predictive/diagnostic capability through the development of new types of contrast agent. Since 1993, the PI has been advising two of the major European Contrast Agent/Imaging companies and so is able to contact either Bracco spa (Milano/Ivrea) and/or Guerbet sa (Paris) to assess their level of commercial interest. More recently, the PI was a key scientific adviser a multi-district litigation (4 bellwether trials, scores of cases settled out of Court in 2011/12), as a result of the poor kinetic stability of acyclic gadolinium contrast agents (e.g. Omniscan/Optimark) that were given to patients with renal failure and who subsequently developed nephrogenic systemic fibrosis. The PI has a record of assessing the impact of such work, and the need to behave cautiously when raising interest/awareness (e.g. via media releases) in considering the true prospects for such work.