Ultrahard Molecular Magnets Based on Heavy Transition Metals

Description du projet

Construire la nouvelle génération d’aimants moléculaires

Les aimants permanents sont essentiels à la technologie moderne, mais les aimants composés de terres rares dépendent de matériaux importés et sont difficiles à ajuster. Les aimants à base de molécules constituent une alternative légère, souple et personnalisable, mais la plupart reposent sur des métaux 3D, laissant les structures métalliques 4D et 5D largement inexplorées. Soutenu par le programme Actions Marie Skłodowska-Curie, le projet UltraMolMag entend synthétiser des systèmes métal-radical utilisant des centres cationiques 4D et 5D, débloquant un couplage spin-orbite plus fort et des propriétés magnétiques ultra-dures à température ambiante. En ajustant soigneusement la chimie de coordination et en construisant des cadres radicaux étendus, les chercheurs créeront des aimants poreux dont l’hystérésis magnétique peut être contrôlée par l’adsorption d’invités, ouvrant ainsi la voie à des aimants moléculaires durables et hautement performants.

Objectif

Molecule-based magnets are crystalline materials that exhibit magnetic properties analogous to those observed in traditional permanent magnets, but they can also show unique desirable functionalities, including low density, mechanical softness and physical tunability. In particular, the use of organic radicals in combination with 3d metals has been demonstrated by the Host group of Dr. hab. Rodolphe Clérac to produce high-temperature molecular magnets. However, frameworks featuring cationic 4d and 5d metal nodes are significantly underrepresented in this field of research, despite the fact that they offer more diffused d orbitals and greater spin-orbit coupling. The combination of these characteristics with the strong magnetic coupling offered by the radical ligands should result in the creation of ultrahard magnets operating at room temperature. This would challenge the monopoly of rare-earth magnets, the production of which is dependent on the supply of precursors that must imported into the EU. Therefore, the main objective of the UltraMolMag project is to develop a suitable synthetic methodology for the preparation of metal-radical systems featuring 4d and 5d elements as cationic centers. Their incorporation into extended systems is a formidable challenge, however, they can be tamed by the chemical tuning of the coordination sphere. In this project inert metal centers will be activated by preparing precursor complexes with labile substituents. Conversely, the unwanted catalytic activity will be mitigated by binding metal ions in the form of pre-organized units. The ultimate aim is to develop porous magnets based on extended radical anions, which will for the first time enable control over magnetic hysteresis through guest adsorption at room temperature. The implementation of this project will result in the creation of a library of heavy transition metal precursors and the fellow will receive training in the characterization of target frameworks.