Thermomètres Luminescents à Base de Complexes de Lanthanide(III)

La température est un paramètre qui joue un rôle fondamental dans la dynamique des systèmes naturels et artificiels. Bien que plusieurs méthodes de mesure aient été développées au fil du temps, les technologies actuelles ont augmenté la demande pour développer de nouveaux dispositifs permettant une mesure de la température avec une grande précision jusqu'aux échelles nano- et micrométriques. À cet égard, les thermomètres luminescents apparaissent dans les études récentes comme des outils prometteurs présentant des sensibilités et une résolution spatiale élevées, ainsi que des temps de réponse courts. En particulier, leur caractère non invasif pourrait être intéressant dans le contexte de l'imagerie biologique. Parmi cette famille, les thermomètres luminescents à base d’ions lanthanides(III) suscitent un grand intérêt en raison de leurs propriétés photo-physiques uniques. Dans ce manuscrit, nous présentons la conception de thermomètres ratiométriques et à durée de vie de luminescence, basés sur des centres émetteurs Ln(III). De bonnes performances ont été obtenues en mesurant la variation d’intensité d’émission de mélanges de complexes d’ions Eu(III) et Tb(III). Les transferts d'énergie entre les deux espèces émettrices ont été modulés, grâce à la modification du ligand et à son impact sur les états excités impliqués dans le processus et la morphologie des matériaux préparés. Ces matériaux présentent une grande facilité de mise en forme et des performances prometteuses en tant que capteurs de température. En particulier, leurs bonnes sensibilités dans la gamme des températures physiologiques en font des candidats attrayants comme précurseurs de futures sondes biologiques.Temperature is an essential parameter that plays a crucial role in the dynamics of natural and artificial systems. Although several reading methods have been developed over time, current technologies have increased the demand to develop new methods with high accuracy down to micro -and nano-scales. In this respect, luminescent thermometers have emerged in the studies as promising tools showing high sensitivities and spatial resolution, in addition to short response times. In particular, their non-invasive nature could be of interest in the context of biological imaging. Among this family, Lanthanide(III)-based luminescent thermometers take a great interest due to their unique photo-physical properties. In this manuscript, we will present the design of ratiometric and luminescence lifetime thermometers, based on Ln emitting centers. Good performances were achieved by following the variation of the emission of mixtures of Eu(III) and Tb(III) complexes. The transfers of energy in between both emitting species were modulated, thanks to the modification of the ligand and its impact on the excited states involved in the process and the morphology of the prepared materials. These materials show a straightforward processability and promising performances as temperature sensors. In particular, their good sensitivities in the physiological range makes them appealing candidates as precursor for future biological probes

Cyclam as Relevant Platform to Design 99mTc, 64Cu, or 109Pd Radiopharmaceuticals in Nuclear Medicine

International audienc

The mischievous properties of Ln(III) complexes: switching the luminescence for unexpected reasons

National audiencePrevious works of our team were dedicated to the design and the study of lanthanide complexes with high-brightness due to the sensitization by tailor-made charge-transfer antennas, enabling tridimensional functional imaging through two-photon excitation..

Comprehensive photophysical and nonlinear spectroscopic study of thioanisolyl‐picolinate triazacyclononane lanthanide complexes

International audienceAbstract Detailed photophysical studies of luminescent lanthanide complexes are presented and elaborated using a newly developed thioanisolyl‐picolinate antenna and the related tacn macrocyclic ligand. The new ligand proved to sensitise Nd(III), Sm(III), Eu(III) and Yb(III) emission. Eu(III) complex showed complete energy transfer, yielding high quantum yield (44 %) and brightness, while the Tb(III) analogue underwent a thermally activated back‐energy transfer, resulting in a strong oxygen quenching of the triplet excited state. Transient absorption spectroscopy measurements of Gd(III), Tb(III) and Eu(III) compounds confirmed the sensitization processes upon the charge‐transfer antenna excitation. The triplet excited state lifetime of the Tb(III) complex was 5‐times longer than that of the Gd(III) analogue. In contrast, the triplet state was totally quenched by the energy transfer to the 4f ‐metal ion in the Eu(III) species. Nonlinear two‐photon absorption highlighted efficient biphotonic sensitization in Eu(III) and Sm(III) complexes. In case of the Nd(III) compound, one‐photon absorption in 4f–4f transitions was predominant, despite the excitation at the antenna two‐photon band. This phenomenon was due to the Nd(III) 4f–4f transitions overlapping with the wavelength‐doubled absorption of the complex

Hysteresis Photomodulation via Single-Crystal-to-Single-Crystal Isomerization of a Photochromic Chain of Dysprosium Single-Molecule Magnets

International audienc

Relevance of Oxocyclam from Palladium(II) Coordination to Radiopharmaceutical Development

International audienceWe provide a comprehensive study of the coordination of oxocyclam with palladium(II), including presentation of a novel bifunctional analogue, p-H2N-Bn-oxocyclam, bearing an aniline pendant. The complexation of palladium(II) with oxocyclam was examined by various techniques, including NMR analysis and potentiometric titrations which revealed that the Pd(II) complex can adopt different configurations such as trans-I and trans-III. In addition, oxocyclam forms a thermodynamically stable palladium(II) complex, the stabilization being attributed to the deprotonation of the amide function. The crystal structures of [Pd(H–1oxocyclam)]+ and [Pd(oxocyclam)]2+ were obtained, revealing the structural details previously anticipated, including, in the second case, the presence of the proton on the carbonyl oxygen atom. Additionally, the study explored the redox behavior of the Pd(II)-oxocyclam complex through reduction and oxidation voltammograms at different pH values. Successful 109Pd-labeling of oxocyclam and p-H2N-Bn-oxocyclam at pH 3.5 demonstrated high labeling efficiencies, whatever the species formed. The stability of the radiocomplexes was assessed and moderate transchelation toward EDTA was observed. Overall, oxocyclam displayed favorable properties for Pd(II) coordination and radiolabeling, suggesting its potential as a chelating agent for this metal in palladium-based applications