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Philippe SAINCTAVIT (SOLEIL)26/02/2024, 14:30
In this presentation we shall give an introduction to the technique of X-ray absorption spectroscopy (XAS).
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In a first step, we shall focus on the basic theoretical description of XAS with a specific attention dedicated to the selection rules and we shall also review the theoretical framework necessary for the description of the electronic structures of the rare earths in the context of XAS.... -
Valérie MARVAUD (CNRS - IPCM)26/02/2024, 15:30
High spin molecules and photomagnetic compounds are attracting increasing attention due to their potential interest in memory devices or optical switches. On the one hand, lanthanides have been recognized as viable building blocks for single molecule magnets (SMM) due to their strong single-ion anisotropy. On the other hand, octacyanometalates could be considered as interesting precursors not...
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Ewen Lescop (ICSN-CNRS)26/02/2024, 16:30
The application of hydrostatic high-pressure (HP) is now a recognized tool to modify biomolecular conformational landscapes in a mild and largely reversible manner. HP combined with NMR spectroscopy (HP-NMR) has been extensively used over the years to characterize the folding properties and the dynamics of soluble proteins by stabilizing conformational states that are lowly populated at...
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Christophe DEN AUWER (Université Côte d'Azur)26/02/2024, 17:00
Since the discovery and early developments of radiochemistry by P. and M. Curie at the beginning of the XXth century, the chemistry of radioactive nuclides has undergone spectacular progresses during the first half of the century. Since then the term radiochemistry broadly covers the chemistry at tracer scale from early Curie’s methodologies1 and the chemistry of radionuclides. The IUPAC gold...
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Adrien COMBOURIEU26/02/2024, 19:00
Catalysis is a fascinating opportunity for chemists to unbolt new reaction pathways in mild conditions. Among promising fields of catalysis, photoredox catalysts have shown good reactivity. However, mostly-used photocatalysts are still mainly based on precious metals such as iridium and ruthenium. Efforts to develop more abundant metals photoactive complexes brought some examples using iron,...
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Claire LE NAOUR (CNRS IJCLAb UMR 9012)26/02/2024, 19:20
Le protactinium connaît actuellement un regain d’intérêt en raison d’une application potentielle dans différents domaines en marge du nucléaire civil (réacteur à combustible thorium, accumulation de 231Pa dans les résidus miniers d’uranium) : détermination du rapport 231Pa/230Th en océanographie et du rapport 231Pa/235U en criminalistique nucléaire ou géochronologie, irradiation de 231Pa ou...
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Claire Squarzoni (LCM - Ecole Polytechnique)26/02/2024, 19:40
The transition from the exploitation of fossil fuels to the efficient use of sustainable energies is the main goal of the researchers of the 21st century. Hydrogen has emerged as a clean fuel alternative to fossil energies, due to its absence of carbon dioxide emission when used. [1]
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However, the production of green hydrogen has been very challenging and is today a focus of the scientific... -
Lucie PEDUSSAUT26/02/2024, 20:00
The cyclonatetraenyl (Cnt) anion is nine-membered ring that was first synthesize in 1963 by Katz and Garrat.1 This compounds features two isomers: the cis,cis,cis,cis- Cnt and the cis,cis,cis,trans-Cnt as depicted in Figure 1. At that time, scientist observed spontaneous isomerization from the trans form to the cis one. Given the aromatic character of the fully cis form, it was considered the...
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Thomas SIMLER (LCM, Ecole Polytechnique, CNRS)26/02/2024, 20:20
Divalent lanthanide complexes are attractive single-electron reductants as their reactivity can be tuned by the nature of both the Ln(II) metal centre and the ligand. In this context, Ln(II) complexes have been actively investigated for the activation and transformation of small molecules. In particular, homogeneous complexes allowing the activation and valorisation of CO under mild conditions...
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Angus Shephard (Ecole Polytechnique)26/02/2024, 20:40
Aromatic ligands have provided a wealth of interesting organometallic complexes of f-elements, namely featuring cyclopentadienyl (Cp, C5H5-) or cyclooctatetraenyl (Cot, C8H82-) frameworks.[1,2] In recent years, this area has been expanded to include the cyclononatetraenyl (Cnt, C9H9-) ligand, which exhibits unique coordination modes to late lanthanide centres of the general form Ln(Cnt)3 (Ln...
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Cédric Pécou (IPCM - Sorbonne Université)26/02/2024, 20:40
Résumé: Developed in the 1980s, dendrimer chemistry has opened up new perspectives in fields as diverse as catalysis, molecular electronics and artificial photosynthesis.[1] Surprisingly, however, magnetic dendrimers are not common in the literature due to puzzling difficulties in their synthesis and characterization.[2] In this context, the design of such multimetallic and monodisperse...
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Dr Luca Demonti (Institut Polytechnique de Paris)26/02/2024, 20:40
The chemistry of organometallic palladium complexes is largely dominated by the 0 and +II metal’s oxidation states due to their central relevance in cross-coupling transformations.[1] However, higher oxidations states of the metal are being explored in the effort to access previously precluded transformations and to unveil unprecedented reactivity at the metal centre.[2,3]
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The coordination of... -
Eric Girard27/02/2024, 09:00
Au cours de cette présentation, j’exposerai les challenges passé, présent et futur associés à l’obtention d’information structurale sur des macromolécules biologiques. Je me focaliserai sur l’apport des complexes de lanthanide dans la levée de problématiques méthodologiques pour les deux techniques que sont la diffraction des rayons X, en particulier pour la production de cristaux de...
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Nadège Hamon (Université de Bretagne Occidentale)27/02/2024, 10:00
Lanthanide Luminescent Bioprobes (LLBs) exploit the pecular properties of lanthanides such as sharp and intense emission band spread from the visible to the Near Infra-Red (NIR) and long luminescent lifetimes (up to ms for Eu and Tb), which make them useful tools for time-resolved optical imaging. Structurally, LLBs consist in lanthanide chelates functionalized with a chromophore in charge of...
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François Riobé (ICMCB -Bordeaux)27/02/2024, 11:00
Recent years have seen a renewed interest in circularly polarized luminescence (CPL), the emission asymmetry observed with luminescent chiral molecules. These studies are driven by potential applications, such as bioprobes for microscopy or optimized dyes for current displays, and by the widespread availability of CPL spectrophotometers. While chiral lanthanide(III) complexes are considered...
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Ms Amal Bouammali27/02/2024, 11:30
Les complexes sandwichs divalents volumineux de lanthanides suscitent actuellement un grand intérêt dans le domaine de la recherche scientifique eu égard à leur stabilité, leur réactivité et leurs propriétés physiques incontournables.[1] Les ligands à base de polyarylcyclopentadiényle semblent des candidats très prometteurs dans la synthèse de ce type de structures, en raison de leurs...
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Olivier Maury (CNRS-ENS de Lyon)27/02/2024, 11:50
Luminescent lanthanide complexes find broad application in UC processes and beyond: in lasers or displays, in solar cells, as anti-counterfeit materials, in photocatalysis and particularly as bioprobes in photodynamic therapy or imaging. Owning the particular nature of the 4f-electrons, the photophysical properties of f-element are uniques (parity-forbidden f-f transition, sharp transition,...
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Pier-Lorenzo SOLARI (SOLEIL)27/02/2024, 12:10
MARS (Multi-Analyses on Radioactive Samples) beamline at the SOLEIL synchrotron is opened to the international community since 2010 and is dedicated to the study of radioactive samples [1] with a specific radioprotection safety design that fulfills the French ASN (Autorité de Sureté Nucléaire) requirements. The beamline is fully devoted to advanced structural and chemical characterizations of...
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Emmanuel Flurin (CEA)27/02/2024, 17:15Conférence Invitée
Electron spin resonance (ESR) spectroscopy is the method of choice for characterizing paramagnetic impurities, with applications ranging from chemistry to quantum computing, but it gives only access to ensemble-averaged quantities due to its limited signal-to-noise ratio. The sensitivity needed to detect single electron spins has been reached so far using spin- dependent photoluminescence,...
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Philippe Moisy28/02/2024, 09:00
Cette présentation sera l’occasion dans un premier temps de discuter des propriétés chimiques des éléments actinides (5f) les plus marquantes en solution aqueuse. Parmi celles-ci, le comportement rédox sera plus particulièrement abordé.
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Dans une seconde étape, les grands axes de Recherche & Développement seront présentés, en se focalisant sur les éléments transuraniens (Z>92).
Enfin, une... -
Hélène Bolvin (LCPQ-FeRMI Université de Toulouse 3)28/02/2024, 10:00
Paramagnetic NMR measures the NMR chemical shift of paramagnetic complexes compared to their diamagnetic counterpart. This shift may be split into
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dipolar terms, arising from the magnetic dipolar interaction between the metal center and the NMR active nucleus, and the contact term, due to the spin delocalization leaking from the paramagnetic center towards the ligand [1]. The separation of... -
18. Vers le décryptage des étapes de nucléation et croissance des nanoparticules colloïdales de PuO2Dr Simon Bayle (CEA/ICSM)28/02/2024, 11:00
Une meilleure compréhension des propriétés structurales et physico-chimiques des nanoparticules colloïdales d'oxyde de plutonium (PuO2) suscite un intérêt pour élucider les schémas de migration environnementale de cet élément radioactif à vie longue, mais aussi pour le développement potentiel de combustibles nucléaires avancés.[1,2] Les suspensions colloïdales issues de l'hydrolyse de Pu(IV)...
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Margherita Colombo (CNRS-UCBL1)28/02/2024, 11:20
The field of molecular magnetism has witnessed remarkable progress in the last decades, fuelled by the discovery of single-molecule magnets (SMMs).[1,2,3] Research into SMMs in the decades that followed saw the introduction of lanthanide ions into these complexes thanks to their high spin and strong intrinsic magnetic anisotropy.[4,5] Some lanthanide ions also have very specific optical...
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Linda De Marchi (IP Paris - Ecolé Polytechnique)28/02/2024, 11:40
Palladium-mediated transformations are dominated by Pd ()0 and Pd(II) species, whereas the reactivity of higher oxidation states such as Pd(III) and Pd(IV) are far less explored because of the low accessibility and stability of these species.[1]
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Herein, we present the synthesis, characterization, and reactivity of a novel Pd(IV) - alkyl complex.
The stabilization of the Pd(IV) species...
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