In this presentation we shall give an introduction to the technique of X-ray absorption spectroscopy (XAS).
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....
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...
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...
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...
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]
However, the production of green hydrogen has been very challenging and is today a focus of the scientific...
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...
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...
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...
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]
The coordination of...
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...
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...
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,...
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...
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,...
Paramagnetic NMR measures the NMR chemical shift of paramagnetic complexes compared to their diamagnetic counterpart. This shift may be split into
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...
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)...
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...
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]
Herein, we present the synthesis, characterization, and reactivity of a novel Pd(IV) - alkyl complex.
The stabilization of the Pd(IV) species...
