Pressure-Tuning Interactions in Molecule-Based Magnets
Lead Research Organisation:
Newcastle University
Department Name: School of Chemistry
Abstract
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Organisations
People |
ORCID iD |
| Michael Probert (Principal Investigator) |
Publications
Craig GA
(2015)
A high-pressure crystallographic and magnetic study of Na5[Mn(l-tart)2]·12H2O (l-tart = l-tartrate).
in Dalton transactions (Cambridge, England : 2003)
Sotelo J
(2015)
Locating Gases in Porous Materials: Cryogenic Loading of Fuel-Related Gases Into a Sc-based Metal-Organic Framework under Extreme Pressures.
in Angewandte Chemie (International ed. in English)
Woodall CH
(2016)
Pressure induced enhancement of the magnetic ordering temperature in rhenium(IV) monomers.
in Nature communications
| Description | The central idea of this project is that we can understand the connection between the magnetic properties of a material and its structure by compressing or distorting geometry with high pressure and at the same time measuring how the magnetic properties change. We have recently shown that in two mononuclear Re complexes compression of intermolecular ligand-ligand contacts leads to a linear increase in the long-range magnetic ordering temperature. In one case the temperature increase by a factor of approximately four. This work has recently been the subject of a highlight on the Diamond Synchrotron web-site (see URL link below) and a talk at Diamond Light Source. The work is published in Nature Communications. 7, 13870 (2016). In work on the sodium salt of a manganese tartrate complex the effect of high pressure was focussed entirely around the sodium sites in the structure.This result opens-up a new strategy for directing the effects of compression towards specific moieties by incorporating them them in a rigid framework. This work is available in Dalton Transactions. 44, 42, p. 18324-18328 (2015). In addition to work on structure-property relationships in specific materials we have also made some key methodological advances. Many of the properties of molecular magnets are low-temperature phenomena and it is highly desirable to measure structure under the same conditions. Until now this has been extremely difficult because pressure cells are bulky devices that are hard to cool. We have developed the first 3D printed pressure cell which is small enough to be accommodated in commonly available open-flow cryostats available most crystallographic labs. The key development was to recognise that the screw-threads that connect the two halves of the pressure cell together can be idealised and miniaturised more readily using 3D printing than by conventional machining. The work is described in Review of Scientific Instruments. 88, 035103 (2017). For even lower temperatures it is now possible via our link with Newcastle University to measure high-pressure data near absolute zero. Neutron diffraction is an important method for studying molecular materials, especially in cases the H-atom positions are important or information of magnetic ordering is required. Until now neutron experiments required much larger crystals than X-ray methods. However we have shown that use of neutron Laue methods yield data suitable for fully anisotropic structure refinement, allowing joint spectroscopic and X-ray and neutron diffraction studies of exactly the same sample. The penetrating powder of neutrons also means that the pressure cell can be accommodated in a cryostat, also enabling temperatures close to absolute zero to be accessed for high pressure measurements. This work is described in IUCrJ. 3, 3, p. 168-179 and was the subject of an internship by one of our team at the ANSTO neutron facility in Sydney. Ultra low temperature structural characterisation, coupled to high pressure environments, completed at Newcastle University was used to underpin and the characterisation of materials descried above by collaborators from Edinburgh University (grant number EP/K033646/1). |
| Exploitation Route | The findings described above have potential applications in using pressure to control of desirable physical properties and to identify the structural distortions needed to promote specific properties. We have focussed on magnetism, but the methods are applicable to any property, e.g. conductivity or spectroscopic response. We continue to make developments at central facilities that are used by numerous other groups. |
| Sectors | Chemicals,Manufacturing, including Industrial Biotechology |
| URL | http://www.diamond.ac.uk/Science/Research/Highlights/2017/high-pressure-magnetism.html |