Molecular magnets and spin transition systems, luminescence and multi-functionality

Keywords : Lanthanide complexes, Single Molecule Magnet, Photochromism

With the prominent use of magnetization-based information storage technologies in our daily life, Single-Molecule-Magnets (SMM), which are able to interconvert between two states with opposite magnetization directions, receive a great deal of attention. Circuits integrating such molecular-scale components may ultimately replace the current technologies. In order to introduce a remote control of this property with light to reach advanced switching systems and devices, we target a new kind of molecular photomagnetism that rely on relies on a ligand-centered light driven process within a metal complex containing photoswitchable ligands. Such strategy is particularly relevant for the otherwise light insensitive 4f based SMM systems because their high sensitivity to minute changes in their coordination environment maximize the impact of the photo-isomerization event on the resulting magnetic behavior.

Contacts : Stéphane Rigaut, Lucie Norel.

Keywords: Lanthanide complexes, NIR Emission, Photochromism, Redox Switches

The switching of near infrared light is a major challenge for various applications in the fields of information transport, medical imaging, detection or authentication of documents. Our group had a pioneering role in both developing redox active ligands that allow the control of NIR emitters luminescence by a change in the redox state and more recently by using photochromic ligand specifically designed to perform luminescence switching with light, an efficient and contactless stimulus. The combination of the two strategies also provides unique switches with dual control. Our efforts are currently directed at developing these dynamic systems towards anticounterfeiting applications, including with combination of lanthanides ions emitting in the visible and the NIR range.

Contacts : Stéphane Rigaut, Lucie Norel, Olivier Galangau.

Keywords: Single-Molecule Magnet, Luminescence, Chirality, Electro-activity

The design of multifunctional materials is a challenge for both chemist and physicist communities eager to know and observe new physical properties resulting from the synergy of others properties. Thus the elaboration of lanthanide luminescent Single-Molecule Magnets allow magneto-structural correlations between magnetism and luminescence since the latter is a photography of the energy splitting at the origin of the magnetic behavior. The introduction of chirality through the use of binaphtyl or helicenes based-ligands induced a differentiation of magnetic behavior between the racemic mixture and the enantiomeric form of the molecular system. Finally when electro-active ligand involving the tetrathiafulvalene fragment is used, the modulation of the physical properties depending of its oxidation state can be ambitioned.

Contacts : Fabrice Pointillart, Olivier Cador

Keywords: Single-Molecule Magnet, Isotopes, Molecular Magnetism

Single-Molecule Magnets (SMMs) are molecular objects capable of storing magnetic information at low temperatures. However, the opening of the hysteresis cycle is thwarted by quantum phenomena (tunnel effect), the origin of which is a perturbation of the electronic magnetic moment. Hyperfine coupling is one of these perturbations and we are developing an original strategy, based on isotopic enrichment, which allows to modulate this coupling. We have applied this strategy to Dy(III) complexes functioning as magnet molecules and highlighted significant modifications of the relaxation phenomena at low temperature as a function of the nuclear spin of the Dy(III) ion but also as a function of the hyperfine coupling constant. This work shows that it is possible to explore the performance of magnet molecules thanks to isotopic enrichment and that, in addition, nuclear spin is a tool for manipulating the electronic magnetic moment on the molecular scale for calculation applications. quantum. This incites us to explore other lanthanide in other systems to confirm or infirm our first assumptions.

Contacts : Fabrice Pointillart, Olivier Cador