Description du sujet de thèse

Molecules are the smallest matter entities that are entirely functionalizable and addressable. Since functional molecules will play a central role in the current miniaturization race, their design and elaboration of are challenging tasks that keep stimulating chemists. On the one hand, it has been proven very recently that the magnetic information can be stored on single molecules (Single-Molecule Magnets: SMMs) at liquid nitrogen temperature. Lanthanide complexes are at the heart of these researches because they combine large magnetic moment and strong magnetic anisotropy due to the large orbital contribution to the magnetic moment and spin-orbit coupling. Magneto-Chiral Dichroism (MChD) in chiral magnetic systems is a fascinating light-matter interaction. The absolute configuration, the direction of light propagation (k) and the relative orientation of the magnetic field (B) lead to an enantioselective modification of the absorption of unpolarized light. The crucial role of the spin-orbit coupling in MChD has been highlighted recently and call for further studies Involving chiral lanthanide-based complexes and especially chiral SMMs that are already magnetized.. In fine lanthanide SMMs showing strong MChD can be seen as ideal candidates for optical readout of magnetic data with unpolarized light. However, to reach this goal one needs to be able to modify MChD response by an external stimulus. Probably, the simplest way is to design switchable complexes in which light induce chemical and/or geometrical modifications. Also, redox activity is a famous tool to tune electronic properties of organic moieties. Then, combination of lanthanide-based SMMs, chirality and switchable ligands offers the possibility to produce switchable MChD responses in molecular magnets. The aim of this project is to design chiral lanthanide SMMs able to display redox- and photo-switching of MChD. To do so, the metallic building blocks (Lanthanide ions) are source of SMM and MChD properties when coordinated to chiral switchable ligands i.e. binaphtyl or helicene moiety connected to a photoisomerizable dithienylethene (DTE) or electro-active tetrathiafulvalene (TTF)). After photo- or redox-switching of the chiral ligand, the lanthanide crystal field is affected, inducing modulation of the magnetic anisotropy, SMM behavior and corresponding MChD signal. With the research program, the PhD candidate will develop skills in in the multistep synthesis of organic ligands, their association with lanthanide ions, the study of their optical and magnetic properties, and the understanding of MChD experiments which are performed in collaboration with a leading team in the field (M. Atzori, C. Train in Grenoble).
Candidate profile:
A motivated student with a very good knowledge in organic synthesis is required. Coordination chemistry skills together with interest for a multidisciplinary project (chemistry, crystallography, magnetism and (chir)optics…) will be appreciated.

Main tasks
- Organic synthesis of helicene, binaphtyl, tetrathiafulvalene and dithienylethene ligands
- Design and elaboration of coordination complexes of lanthanides
- Crystallization of the molecular systems
- usual characterisation techniques

Second tasks
- (photo)Magnetic measurements on SQUID/PPMS
- Redaction of publications

Required know how
- Master/Ingeniering diploma in molecular materials or chemistry
- Deep knowledge in organic chemistry
- NMR, CD absorption spectroscopy
- Coordination chemistry
- stereochemistry and chir(optical spectroscopy

Appreciated know how
- X-ray diffraction
- SQUID/PPMS magnetometry
- Oral presentation of the scientific results
- Redaction of articles

Soft skills
- Working team
- Supervision of students

The University offers French courses for foreigners and hosts an international Erasmus Mundus program. Students should obtain their PhD degree within the 3 years of the financial support (starting date November 2023-January 2024). Rennes is a medium size French city less one hour and half away from Paris, offering a relaxing life style with many cultural and sport activities.
Selected recent publications of the group in the topics of BINOL, Helicene, DTE based-Single Molecule Magnet and MChD:
1) C. A. Mattei, V. Montigaud, V. Dorcet, F. Riobé, G. Argouarch, O. Maury, B. Le Guennic, O. Cador, C. Lalli, F. Pointillart, Luminescent dysprosium single-molecule magnets made from designed chiral BINOL-derived bisphosphate ligands, Inorg. Chem. Front. 2021, 8, 963.
2) M. Hojorat, H. Al Sabea, L. Norel, K. Bernot, T. Roisnel, F. Gendron, B. Le Guennic, E. Trzop, E. Collet, J. R. Long, S. Rigaut, Hysteresis Photomodulation via Single-Crystal-to-Single-Crystal Isomerization of a Photochromic Chain of Dysprosium Single-Molecule Magnets. J. Am. Chem. Soc. 2020, 142, 931
3) M. Atzori, K. Dhbaibi, H. Douib, M. Grasser, V. Dorcet, I. Breslavetz, K. Paillot, O. Cador, G. L. J. A. Rikken, B. Le Guennic, J. Crassous, F. Pointillart, C. Train, Helicene-Based Ligands Enable Strong Magneto-Chiral Dichroism in a Chiral Ytterbium Complex. J. Am. Chem. Soc. 2021, 143, 2671
4) K. Dhbaibi, H. Douib, M. Grasser, V. Dorcet, O. Cador, B. Le Guennic, N. Vanthuyne, F. Riobé, O. Maury, S. Guy, A. Bensalah‐Ledoux, B. Baguenard, G. Rikken, C. Train, M. Atzori, F. Pointillart, J. Crassous, Multifonctional Helicene-Based ytterbium(III) Coordination Polymer Displaying Circularly Polarized Luminescence, Slow Magnetic Relaxation and Room Temperature Magneto-Chiral Dichroism. Angew. Chem. Int. Ed. 2023, e202215558.

Contexte de travail

The Institut des Sciences Chimiques de Rennes (ISCR) is a joint Research Department (UMR: Unité Mixte de Recherche) associating the CNRS (INC et INSIS), The Université de Rennes, the Ecole Nationale Supérieure de Chimie de Rennes (ENSCR) and the Institut National des Sciences Appliquées de Rennes (INSA de Rennes).

This Institute, founded in January 1st, 2006, gathers together all the academic forces in chemistry from the Rennes site. At the beginning of 2023, it brings together more than 280 permanent people, including approximately 140 assistant-professors and professors, 60 CNRS researchers and 80 engineers and technicians, at the Rennes Beaulieu, Rennes Villejean and Lannion IUT sites, leading to an overall workforce of more than 500 people. Its organisation in eight research teams of various sizes along with two administrative and scientific technical departments, makes it possible to combine effectively the scientific advantages of a structure covering a wide disciplinary field combined with a management supportive of everyone.
The research topcics mainly investigated in the ISCR are
a) Sustainable materials with environmentally friendly materials and processes
b) Energy conversion materials
c) Materials and molecules for the health field

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

none

Informations complémentaires

none