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A venir ...

 
Jeudi 21 Juin 2018
Boris Le Guennic
nstitut des Sciences Chimiques de Rennes, UMR CNRS 6226 Université de Rennes 1, 263 Av. du Général Leclerc, 35042 Cedex Rennes, France
Ab initio calculations of lanthanide complexes: from single molecule magnets to circularly polarized luminescence
Complexes containing trivalent lanthanide ions are of great interest in numerous fields due to their specific spectroscopic and magnetic characteristics. In particular, they can give rise to single molecule magnets (SMM) with slow magnetic relaxation, uniaxial magnetic anisotropy and high-energy barrier to the reversal of the magnetic moment. These features originate from the subtle interplay between the spin-orbit coupling and the crystal field interaction created by the ligands surrounding the lanthanide ion. Few general rules for building SMM have been formulated to date but no fundamental magneto-structural relationship explaining the behavior of lanthanide-based SMM has been proposed yet. To this end, and in addition to experimental evidences (SQUID magnetometry, EPR spectroscopy, polarized neutron diffraction...) ab initio calculations (SA-CASSCF/PT2/SI- SO) are one of the most appropriate theoretical tools to get reliable insights into the electronic structure of these compounds. Herein, the recent elucidation of the magnetic behavior of several lanthanide-based complexes is reported.[1] The limits of this computational approach is discussed. Finally, recent advances in the calculations of circularly polarized luminescence (CPL) and paramagnetic NMR (pNMR) in lanthanide complexes are also presented. [1] a) T. T. da Cunha, J. Jung, M.-E. Boulon, G. Campo, F. Pointillart, C. L. M. Pereira, B. Le Guennic, O. Cador, K. Bernot, F. Pineider, S. Golhen, L. Ouahab J. Am. Chem. Soc. 2013, 135, 16332. b) F. Pointillart, B. Le Guennic, O. Cador, O. Maury, L. Ouahab, Acc. Chem. Res., 2015, 48, 2834. c) J.-K. Ou-Yang, N. Saleh, G. Fernandez Garcia, L. Norel, F. Pointillart, T. Guizouarn, O. Cador, F. Totti, L. Ouahab, J. Crassous, B. Le Guennic Chem. Commun. 2016, 52, 14474. d) F. Pointillart, O. Cador, B. Le Guennic, L. Ouahab Coord. Chem. Rev. 2017, 346, 150. e) M. Xémard, A. Jaoul, M. Cordier, F. Molton, O. Cador, B. Le Guennic, C. Duboc, O. Maury, C. Clavaguéra, G. Nocton Angew. Chem. Int. Ed. 2017, 56, 4266. f) L. Norel, L. E. Darago, B. Le Guennic, K. Chakarawet, M. I. Gonzalez, J. H. Olshansky, S. Rigaut, J. R. Long Angew. Chem. Int. Ed. 2018, 57, 1933.

Jeudi 12 Juillet 2018
Dr. Cyrille Monnereau
Ecole Normale Supérieure de Lyon
Fluorescent Polymers with nonlinear absorption properties: their photophysics, fate in living organisms and use as selective probes for biomolecules
The lecture will focus on the making of chromophores with optimized spectroscopic properties to be used as two-photon fluorescent probes for biomedical applications. More specifically, we will focus on their molecular engineering and design, their subsequent integration into water soluble, biocompatible polymeric objects, and some preliminary imaging studies in and ex vivo. We will show that modifications of the polymer structure with cationic groups can lead to a consistent enhancement of their affinity towards biomacromolecules, and illustrate the benefits of this approach for selective recognition of various proteins and DNA sequences.