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Cyclometalated luminescent platinum(II) complexes of dissymmetrical 2,2':4',2"terpyridine and its self-assembled dimer presenting Pt-Ag dative bonds
No full textInternational audienceA series of cyclometalated (N^C^N) Pt(II)-platinum complexes featuring a terpyridine ligand with a non-coordinating nitrogen atom and a Pt-C bond was synthesized. In the presence of Ag + , the bis(isonitrile)Pt(II) complex formed a remarkable self-assembled helicoidal dimer stabilized by coordination of Ag(I) and metallophilic Pt-Ag interactions. Its assembly was observed in the solid state and maintained in solution. All complexes show strong luminescence and multiple emitting states, which could be rationalized based on solid state X-ray structures and coordinating environment
Design of ternary catalysts combining copper with p-block elements to control the electrochemical carbon monoxide reduction
No full textNational audienc
Détermination du mécanisme d'action de peptides antimicrobiens sur des bactéries, par RMN solide in vivo à l'échelle moléculaire
No full textStaphylococcus aureus is a bacterium resistant to many antibiotics, and new treatments are being sought to combat it. DMS-DA6-NH₂, an antimicrobial peptide of amphibian origin, has shown remarkable efficacy against Gram-positive strains, including S. aureus, with minimum inhibitory and bactericidal concentrations of 1.6 µM. Its mechanism of action was unclear, but the use of in vivo Deuterium Nuclear Magnetic Resonance (²H NMR) helped to better understand it. This technique involves labeling the bacterial membrane with deuterated fatty acids, and analyzing the membrane rigidity affected by the peptide. The results were compared to those of lytic peptides such as aurein 1.2 and caerin 1.1, revealing that DMS-DA6-NH₂ acts via a lytic mechanism by forming pores in the S. aureus membrane. Further studies using solid-state NMR and microscopy showed that the peptide also targets the bacterial cell wall by interacting with teichoic acid and peptidoglycan. In parallel, a method was developed to track the incorporation of deuterated fatty acids into the membrane. This method uses gas chromatography coupled with mass spectrometry to study the active or passive labeling of bacterial membranes, determining whether the fatty acids are metabolized and used in the biosynthesis of phospholipids, or remain unchanged in the membrane, depending on the detergent used.Staphylococcus aureus est une bactérie résistante à de nombreux antibiotiques, et de nouveaux traitements sont recherchés pour la combattre. Le DMS-DA6-NH₂, un peptide antimicrobien d'origine amphibienne, a montré une efficacité remarquable contre les souches Gram-positives, dont S. aureus, avec des concentrations minimales inhibitrices et bactéricides à 1,6 µM. Son mécanisme d'action n'était pas clair, mais utilisant la Résonance Magnétique Nucléaire (RMN) in vivo du deutérium (²H) a permis de mieux le comprendre. Cette technique consiste à marquer la membrane bactérienne avec des acides gras deutérés et à analyser la rigidité membranaire affectée par le peptide. Les résultats obtenus ont été comparés à ceux de peptides lytiques comme l'auréine 1.2 et la caérine 1.1, révélant que le DMS-DA6-NH₂ agit via un mécanisme lytique en formant des pores dans la membrane de S. aureus. Des études supplémentaires par RMN solide et microscopie ont montré que le peptide cible également la paroi bactérienne, en interagissant avec l'acide téichoïque et le peptidoglycane. En parallèle, une méthode pour suivre l'incorporation des acides gras deutérés dans la membrane a été développée. Celle-ci utilise des techniques de chromatographie gazeuse couplée à la spectrométrie de masse pour étudier le marquage actif ou passif des membranes bactériennes, déterminant si les acides gras sont métabolisés et utilisés dans la biosynthèse des phospholipides, ou s'ils sont inchangés dans la membrane, selon le détergent employé
Formation of 3-Alkynylidenephthalides by Gold(I)-Catalyzed Alkynylative Cyclization of o-Alkynylbenzoic Acids under Visible Light Irradiation
No full textInternational audienceHerein, we report a Csp 2 -Csp cross-coupling process involving the merger of gold catalysis and visible light photocatalysis leading to the alkynylative cyclization of o-alkynyl benzoic acids. The corresponding and previously undescribed alkynylidenephthalide products were obtained as mixtures of E:Z isomers. The key C-C bond formation is based on the photoactivation of the oxidative addition of an alkynyliodide to a vinylgold(I) intermediate resulting from an initial 5-exo-dig cyclization pathway, as supported by mechanistic studies including DFT calculations
Preface to the ICL 2023 special issue
No full textInternational audienceThe conference was dedicated to the memories of François Auzel and Alexander Kaplyansky, two pioneers and prominent figures in the field of luminescent materials and processes, who recently passed away
Modélisation thermodynamique du système réciproque CaO-CaF2-B2O3-BF3
No full textInternational audienceThe generation of UV light in single crystals by means of the use of their nonlinear optical (NLO) properties is the desired path to design all solid-state UV coherent light sources. Such devices aim to replace the current excimer lasers and to find large number of applications (micro-via drilling in microelectronics, plastic marking, LED's substrate dicing, etc). In the field of materials and optics to develop NLO fluoroborate crystals for an efficient UV conversion, Ca5(BO3)3F (CBF) is one of the most promising potential candidates. This poster describes the thermodynamics of the reciprocal CaO-CaF2-B2O3-BF3 system
Analysis of Battery-like and Pseudocapacitive Ion Intercalation Kinetics via Distribution of Relaxation Times
No full textInternational audienceImproving the kinetics of electrochemical ion intercalation processes is of interest for realizing high-power electrochemical energy storage. This includes classical battery-like intercalation and pseudocapacitive intercalation processes with a capacitor-like electrochemical signature. Electrochemical methods are needed to probe the kinetics of such complex multistep processes in detail. Here, we present the use of the distribution of relaxation times (DRT) analysis of electrochemical impedance data to identify the kinetic limits of intercalation reactions. We study the lithium intercalation reaction in TiS 2 from organic and aqueous electrolytes as a model system. The material can exhibit both battery-like and pseudocapacitive intercalation regimes depending on the potential range, variable diffusion lengths by adjusting its particle size, and a tunable degree of solvent cointercalation by choosing the electrolyte solvent. Using DRT, we can distinguish between the kinetic limitations imposed by solid-state ion diffusion, interfacial ion adsorption and transport, and ion desolvation processes. Thus, DRT analysis can complement existing methods, such as voltammetry or 3D-Bode analysis, to better understand the kinetics of intercalation reactions
Mesure des écarts de température par photoluminescence dans les cellules solaires à porteurs chauds : vers une étude des dispositifs non idéaux.
No full textHot-carrier solar cells promise theoretical efficiencies exceeding 66%. However, actual devicesexhibit significantly lower efficiencies, around 10%. To understand this discrepancy, it is necessary to complicate our understanding of hot-carrier solar cells by introducing non-ideal effects. In this thesis, we study two “uneven temperature” effects: (i) the existence of a temperature gradient within the absorber (inhomogeneous temperature) and (ii) the existence of two different temperatures for electrons and holes. In the first case, we propose a theoretical description of transport adapted to this specific situation. We show that the transport is ambipolar and thermoelectric, and we propose a theoretical expression for the transport coefficients. Next, we suggest an experiment based on hyperspectral photoluminescence imaging in steady-state to characterize transport coefficients. In particular, we measure the ambipolar Seebeck coefficient of an (In,Ga,As)P quantum well. In the second case, we begin by proving that electron and hole temperatures s are both accessible through steady-state photoluminescence spectroscopy. Indeed, the absorptivity of a sample depends on the distributions of electrons and holes due to the ”band filling” effect. This technique requires that the sample be subjected to intense excitation, ensuring that the electrons and holes are in a degenerate regime. Finally, we studied the impact of these two uneven temperature effects on the operation of hot-carrier solar cells. We first calculated the voltage of a cell subject to either of these effects and showed that they result in identical cell voltage. We then demonstrated that the temperature difference between electrons and holes (at a fixed effective temperature) leads to an increase in cell efficiency, by about 1 to 2 points maximum. This effect being limited, precise characterization of electron and hole temperatures is unnecessary to design hot-carrier solar cells.Les cellules solaires à porteurs chauds promettent des rendements théoriques supérieurs à 66%. N´néanmoins, les dispositifs réels ont des rendements nettement inférieurs, de l’ordre de 10%. Pour comprendre cette différence, il est nécessaire de complexifier notre compréhension des cellules solaires à porteurs chauds en introduisant des effets non-idéaux. Dans cette thèse, nous étudions deux effets ≪ d’écart de température ≫: (i) l’existence d’un gradient de température dans l’absorbeur (température inhomogène) et (ii) l’existence de deux températures différentes pour les électrons et les trous. Dans le premier cas, nous proposons une description théorique du transport adaptée à cette situation particulière. Nous montrons que le transport est ambipolaire et thermoélectrique, et proposons une expression théorique pour les coefficients de transport. Ensuite, nous proposons une expérience basée sur une mesure hyperspectrale de photoluminescence en régime continu pour caractériser les coefficients de transport. Nous mesurons en particulier le coefficient Seebeck ambipolaire d’un puits quantique de (In,Ga,As)P. Dans le second cas, nous commençons par prouver que la température des électrons et des trous sont toutes deux accessibles par une simple mesure de photoluminescence en régime continu. En effet, l’absorptivité ´e d’un échantillon dépend des distributions des électrons et des trous grâce au terme de ≪ band filling ≫. Cette technique nécessite que l’échantillon soit soumis à une excitation intense, de sorte que les électrons et les trous soient dans un régime dégénère. Enfin, nous avons étudié l’impact de ces deux effets sur l’opération des cellules `a porteurs chauds. Nous avons d’abord calcul ´e le voltage d’une cellule sujette à l’un ou l’autre de ces deux effets d’écart de température, et montré qu’ils sont identiques. Ensuite, nous avons montré que la différence de température entre les électrons et les trous (à température effective fixée) conduit `a une augmentation de l’efficacité de la cellule, de l’ordre de 1 `a 2 points maximum. Cet effet ´ étant limité, il n’est pas nécessaire de caractériser avec précision la température des électrons et des trous, la connaissance de la température effective semble suffisante
Combining Physics-Based Modeling and Artificial Intelligence for the Optimization of Battery Manufacturing Processes
No full textInternational audienceThe rapid scaling up and process optimization of manufacturing are essential to keep up with current demand and reduce the cost of lithium-ion batteries. In particular, electrode and cell processing and optimization are key in ensuring reliable lithium-ion batteries. Here, we explain how our hybrid modeling approach, combining physics-based simulations and artificial intelligence, can be used to gain insights into performance-manufacturing relationships and optimize the battery cell manufacturing processes. This hybrid approach is a powerful tool that can simulate the various manufacturing steps from powder to power. With this approach, in combination with the acquisition of battery manufacturing pilot line data, it is possible to perform inverse design of the electrode microstructures and cells for optimal properties. A wide diversity of process parameters is taken into account, such as those in the slurry, its drying, and the resulting electrode calendering, together with the parameters associated with the electrolyte filling, the formation, and the electrochemical operation. We briefly discuss various works done under the umbrella of our ARTISTIC project initiative, demonstrating a comprehensive hybrid approach to pave the way toward digital twins of the manufacturing process of lithium-ion and (also) next-generation battery cells