synthetic coordination chemistry and molecular magnetism.
We are a synthetic inorganic group with interests in the areas of coordination chemistry and the magnetic applications of polymetallic complexes.
Underpinning all our research is an understanding of the fundamental relationship between structure and magnetic properties. We examine magneto-structural correlations on a plethora of 3d/4f complexes ranging from dimers and trimers through to molecules containing tens if not hundreds of metal centres, to gain insight into the nature of magnetic exchange and how it is controlled by changes in structure.
We routinely employ hydrostatic pressure as a means of characterising structure-property relationships in coordination compounds. These can be molecular or non-molecular systems in pursuit of uncovering a host of novel high pressure phenomena including bond breaking and formation, dynamic Jahn-Teller distortions, magneto-structural correlations, switching of magnetic exchange interactions, and changes in magnetic ordering temperatures.
Magnetic refrigeration constitutes one of the most promising applications envisioned for molecule-based materials, specifically molecular nanomagnets. The refrigeration process is based on the magnetocaloric effect (MCE), i.e. the change of magnetic entropy and related adiabatic temperature upon change of applied magnetic field. Besides the fundamental interest on related magnetic and magnetothermal properties of novel materials, MCE is of great technological importance since it can be used for cooling applications according to a process known as adiabatic demagnetization. This technique is particularly promising for refrigeration at very low temperature, beyond the reach of liquid helium-4, providing, for example, a valid alternative to the use of helium-3 which is quickly becoming rare and expensive.
Polynuclear clusters of paramagnetic 3d metal ions continue to attract significant interest because of their intriguing geometrical characteristics (large size, high symmetry, aesthetically pleasing shapes and architectures), and fascinating physical properties. Such complexes often combine large and sometimes abnormally large spin ground states with easy-axis-type magnetic anisotropy resulting in a significant barrier to magnetisation relaxation. Thus, at sufficiently low temperatures they function as single domain magnetic particles displaying magnetisation hysteresis and quantum tunneling of the magnetisation (QTM). Such Single-Molecule Magnets (SMMs) represent a molecular approach to nanoscale magnetic materials with potential applications in information storage and molecular spintronics.
In collaboration with Dr Scott Dalgarno at Heriot-Watt University, we are investigating the use of calix[n]arene scaffolds to build paramagnetic cage complexes. By developing a library of cages (more than 100 to date) derived from calix[n]arenes (n = 4-8), homooxacalixarenes and bis-calixarenes we aim to map out assembly modes and coordination constraints of these ligands with Transition and Lanthanide Metal ions under a range of reaction conditions in order to bridge a gap between supramolecular chemistry and molecule-based magnetism.