Louis Caussin PhD defense

Organometallics: Materials & Catalysis (OMC) team Abstract Single-chain magnets exhibit magnetic bistability at the molecular scale and hold promise for high-density information storage. Controlling them with light would provide an additional level of control. This work combines dithienylethene photochromic units, nitronyl-nitroxide radicals, and lanthanide(III) ions, with photoisomerization intended to modulate both magnetic exchange interactions and the ligand field around the metal. Four dithienylethene–nitronyl-nitroxide diradicals and three monoradical analogs were synthesized and characterized. The most compact diradical, previously unreported, exhibits an antiferromagnetic exchange interaction multiplied by a factor of 100 upon ring closure—the strongest reported to date for this family—as well as the first ON/OFF photomodulation of the luminescence of a nitronyl-nitroxide radical. The coordination of these ligands to lanthanide(III) ions led to the first complexes integrating dithienylethene–nitronyl-nitroxide units, in both open and closed forms. Their photochromic and magnetic properties were studied, particularly using torque magnetometry. These results lay the foundation for the development of photocommutable single-chaine magnets based on radicals. Jury Jennifer Molloy, CNRS researcher, University Grenoble Alpes Ie-Rang Jeon, CNRS researcher, University of Bordeaux David Canevet, Professor, University of Angers Mauro Perfetti, Professor, University of Florence Lucie Norel, Professor, ISCR, University of Rennes / PhD Director Kevin Bernot, Professor, INSA Rennes, ISCR, University of Rennes / PhD Co-Director Contacts Louis Caussin, Louis.caussin@univ-rennes.fr Lucie Norel, lucie.norel@univ-rennes.fr Kevin Bernot, kevin.bernot@univ-rennes.fr