Cyclometalated platinum(II) with ethynyl-linked azobenzene ligands: an original switching mode.

International audienceThe photophysical properties of 6-phenyl-2,2'-bipyridyl platinum(ii) complexes bearing different σ-alkynyl-linked azobenzene ancillary ligands were investigated. These complexes exhibited strong, broad, structureless charge-transfer bands in the visible region, which were red-shifted when the electron-donating ability of the para substituent on the azo-acetylide ligand increased. When excited at the charge-transfer absorption band, the complexes exhibited weak green emission, which was assigned to a triplet metal-to-ligand charge transfer/interligand charge transfer emission ((3)MLCT/(3)L'LCT). The presence of an amino substituent in the azobenzene moiety opened the possibility of protonation, which led to the formation of an azonium based derivative and resulted in drastic perturbations of the molecular orbitals and photophysical properties of the Pt-acetylide complex. These studies are fully supported by DFT and TD-DFT calculations

Absorption and Fluorescence Signatures of 1,2,3-Triazole Based Regioisomers : Challenging Compounds for TD-DFT

International audienceIn the continuous quest for improving TD-DFT methodologies as a tool to predict the photophysical features of solvated chro- mophores, we herein investigate two model regioisomers based on the 1,2,3-triazole moiety. Starting from their experimental absorption and emission spectra, key energy differences highlighting the main trends between the two isomers are extracted and used to gauge the accuracy of several levels of theory. RI-CC2 and EOM-CCSD calculations allow us to ascertain that the low energy spectra is not linked to double excitations. In vacuum, neither these methods nor any of the implemented TD-DFT levels of theory, ranging from global hybrids (PBE0, B3LYP) to range-separated functionals without (CAM-B3LYP, ωB97X) or with dispersion corrections (ωB97X-D), is able to capture the key features that differentiate the two chromophores. Accounting for solvent within a specific PCM model allows to recover experimental trends, but the dramatic changes occurring when moving from toluene to THF and/or for different PCM approaches (LR, cLR, SS) suggest that this agreement is probably fortuitous. Even so the ωB97X-D functional combined to the SS-PCM scheme leads to quantitative agreement with experiment, TD-DFT results obtained for 1,2,3-triazole based chromophores need to be treated with caution. We also show that the SS-PCM approach may be useful to test current and novel exchange-correlation functionals against the charge transfer failure

Photoisomerisation in Aminoazobenzene-Substituted Ruthenium(II) Tris(bipyridine) Complexes: Influence of the Conjugation Pathway.

International audienceTransition-metal complexes containing stimuli-responsive systems are attractive for applications in optical devices, photonic memory, photosensing, as well as luminescence imaging. Amongst them, photochromic metal complexes offer the possibility of combining the specific properties of the metal centre and the optical response of the photochromic group. The synthesis, the electrochemical properties and the photophysical characterisation of a series of donor-acceptor azobenzene derivatives that possess bipyridine groups connected to a 4-dialkylaminoazobenzene moiety through various linkers are presented. DFT and TD-DFT calculations were performed to complement the experimental findings and contribute to their interpretation. The position and nature of the linker (ethynyl, triazolyl, none) were engineered and shown to induce different electronic coupling between donor and acceptor in ligands and complexes. This in turn led to strong modulations in terms of photoisomerisation of the ligands and complexes

The TESS Grand Unified Hot Jupiter Survey. I. Ten TESS Planets

We report the discovery of ten short-period giant planets (TOI-2193A b, TOI-2207 b, TOI-2236 b, TOI-2421 b, TOI-2567 b, TOI-2570 b, TOI-3331 b, TOI-3540A b, TOI-3693 b, TOI-4137 b). All of the planets were identified as planet candidates based on periodic flux dips observed by NASA's Transiting Exoplanet Survey Satellite (TESS). The signals were confirmed to be from transiting planets using ground-based time-series photometry, high angular resolution imaging, and high-resolution spectroscopy coordinated with the TESS Follow-up Observing Program. The ten newly discovered planets orbit relatively bright F and G stars ($G < 12.5$,~$T_\mathrm{eff}$ between 4800 and 6200 K). The planets' orbital periods range from 2 to 10~days, and their masses range from 0.2 to 2.2 Jupiter masses. TOI-2421 b is notable for being a Saturn-mass planet and TOI-2567 b for being a ``sub-Saturn'', with masses of $0.322\pm 0.073$ and $0.195\pm 0.030$ Jupiter masses, respectively. In most cases, we have little information about the orbital eccentricities. Two exceptions are TOI-2207 b, which has an 8-day period and a detectably eccentric orbit ($e = 0.17\pm0.05$), and TOI-3693 b, a 9-day planet for which we can set an upper limit of $e < 0.052$. The ten planets described here are the first new planets resulting from an effort to use TESS data to unify and expand on the work of previous ground-based transit surveys in order to create a large and statistically useful sample of hot Jupiters.Comment: 44 pages, 15 tables, 21 figures; revised version submitted to A

A biogeographical appraisal of the threatened South East Africa Montane Archipelago ecoregion

Recent biological surveys of ancient inselbergs in southern Malawi and northern Mozambique have led to the discovery and description of many species new to science, and overlapping centres of endemism across multiple taxa. Combining these endemic taxa with data on geology and climate, we propose the ‘South East Africa Montane Archipelago’ (SEAMA) as a distinct ecoregion of global biological importance. The ecoregion encompasses 30 granitic inselbergs reaching > 1000 m above sea level, hosting the largest (Mt Mabu) and smallest (Mt Lico) mid-elevation rainforests in southern Africa, as well as biologically unique montane grasslands. Endemic taxa include 127 plants, 45 vertebrates (amphibians, reptiles, birds, mammals) and 45 invertebrate species (butterflies, freshwater crabs), and two endemic genera of plants and reptiles. Existing dated phylogenies of endemic animal lineages suggests this endemism arose from divergence events coinciding with repeated isolation of these mountains from the pan-African forests, together with the mountains’ great age and relative climatic stability. Since 2000, the SEAMA has lost 18% of its primary humid forest cover (up to 43% in some sites)—one of the highest deforestation rates in Africa. Urgently rectifying this situation, while addressing the resource needs of local communities, is a global priority for biodiversity conservation

NEID Rossiter–McLaughlin Measurement of TOI-1268b: A Young Warm Saturn Aligned with Its Cool Host Star

Close-in gas giants present a surprising range of stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis. It is unclear whether the obliquities reflect the planets' dynamical history (e.g., aligned for in situ formation or disk migration versus misaligned for high-eccentricity tidal migration) or whether other mechanisms (e.g., primordial misalignment or planet-star interactions) are more important in sculpting the obliquity distribution. Here we present the stellar obliquity measurement of TOI-1268 (TIC-142394656, V mag ∼10.9), a young K-type dwarf hosting an 8.2 day period, Saturn-sized planet. TOI-1268's lithium abundance and rotation period suggest the system age between the ages of the Pleiades cluster (∼120 Myr) and the Prasepe cluster (∼670 Myr). Using the newly commissioned NEID spectrograph, we constrain the stellar obliquity of TOI-1268 via the Rossiter-McLaughlin effect from both radial velocity and Doppler tomography signals. The 3σ upper bounds of the projected stellar obliquity λ from both models are below 60°. The large host star separation (a/R ∗ ∼17), combined with the system's young age, makes it unlikely that the planet has realigned its host star. The stellar obliquity measurement of TOI-1268 probes the architecture of a young gas giant beyond the reach of tidal realignment (a/R ∗ ≲10) and reveals an aligned or slightly misaligned system

Current concept of abdominal sepsis : WSES position paper

Peer reviewe

Absorption à deux photons et photochromisme de complexes de ruthénium : application au stockage optique de données

The development of new technologies , computer and internet in recent decades has been accompanied by an increasing demand for media storage information. In particular , the optical data storage .Conventional media ( CD-ROM , Blu-ray ... ) based on a storage disk surface, have now reached their limits. A new technology being developed , based on a data storage in three dimensions, is a promising alternative to replace conventional materials. Materials must include entities for photochromic properties (molecular switch) and multi- photon absorption demonstrated. In this thesis , we considered the synthesis of functional molecules which present these two characteristics. As a first step , we are interested in the synthesis and comparative study of homo and heteroleptic ruthenium complex having a certain potential for two-photon absorption . We have shown that these systems were very active and they allowed to host a photochromic entity lossless bi- photonic properties. We then studied the properties of originals photochromic ruthenium tris- bipyridine containing an azobenzene motif. The metal complexing profoundly changes the photochromism of azobenzene with significantly different from those ligands kinetics . Finally, we studied the properties of hybrid complexes of ligands for the two-photon absorption and others to photochromism , these compounds are active in both areas. We finally discuss the potential of the optical behavior of compounds of these complex films. We conducted preliminary tests of the SHG signal modulation on these films. We want to maximize all components of the process to determine the potential of these compounds in optical data storage .Le développement des nouvelles technologies, de l'informatique et d'internet ces dernières décennies s'est accompagné d'une demande croissante de supports de stockage de l'information. En particulier, le stockage optique de données. Les supports conventionnels (Cd-Rom, Blue-ray…), basés sur un stockage en surface du disque, ont atteint aujourd'hui leurs limites. Une nouvelle technologie en cours de développement, basée sur un stockage de données en trois dimensions, est une alternative prometteuse pour supplanter les supports conventionnels. Les matériaux doivent intégrer des entités aux propriétés photochromes (commutateur moléculaire) et d'absorption multi-photonique démontrées. Au cours de cette thèse, nous avons envisagé la synthèse de molécules fonctionnelles qui présenteraient ces deux caractéristiques. Dans un premier temps, nous nous sommes intéressés à la synthèse et à l'étude comparative de complexes homo et hétéroleptiques de ruthénium présentant une certaine potentialité pour l'absorption à deux photons. Nous avons montré que ces systèmes étaient très actifs et qu'ils permettaient d'accueillir une entité photochrome sans perte des propriétés bi-photoniques. Nous avons par la suite étudié les propriétés en photochromisme de complexes de ruthénium tris-bipyridine originaux comprenant un motif azobenzène. La complexation au métal bouleverse profondément le photochromisme de l'azobenzène avec des caractéristiques cinétiques notablement différentes de celles des ligands. Enfin, nous avons étudié les propriétés de complexes hybrides composés de ligands pour l'absorption à deux photons et d'autres pour le photochromisme, ces composés sont actifs dans ces deux domaines. Nous discutons finalement du potentiel du comportement optique de films composés de ces complexes. Nous avons procédé à des essais préliminaires de modulation du signal SHG sur ces films. Nous souhaitons optimiser toutes les composantes du processus afin de déterminer le potentiel de ces composés en stockage optique de données

Two photon absorption and photochromism of ruthenium complexes : application optical data storage

Le développement des nouvelles technologies, de l'informatique et d'internet ces dernières décennies s'est accompagné d'une demande croissante de supports de stockage de l'information. En particulier, le stockage optique de données. Les supports conventionnels (Cd-Rom, Blue-ray…), basés sur un stockage en surface du disque, ont atteint aujourd'hui leurs limites. Une nouvelle technologie en cours de développement, basée sur un stockage de données en trois dimensions, est une alternative prometteuse pour supplanter les supports conventionnels. Les matériaux doivent intégrer des entités aux propriétés photochromes (commutateur moléculaire) et d'absorption multi-photonique démontrées. Au cours de cette thèse, nous avons envisagé la synthèse de molécules fonctionnelles qui présenteraient ces deux caractéristiques. Dans un premier temps, nous nous sommes intéressés à la synthèse et à l'étude comparative de complexes homo et hétéroleptiques de ruthénium présentant une certaine potentialité pour l'absorption à deux photons. Nous avons montré que ces systèmes étaient très actifs et qu'ils permettaient d'accueillir une entité photochrome sans perte des propriétés bi-photoniques. Nous avons par la suite étudié les propriétés en photochromisme de complexes de ruthénium tris-bipyridine originaux comprenant un motif azobenzène. La complexation au métal bouleverse profondément le photochromisme de l'azobenzène avec des caractéristiques cinétiques notablement différentes de celles des ligands. Enfin, nous avons étudié les propriétés de complexes hybrides composés de ligands pour l'absorption à deux photons et d'autres pour le photochromisme, ces composés sont actifs dans ces deux domaines. Nous discutons finalement du potentiel du comportement optique de films composés de ces complexes. Nous avons procédé à des essais préliminaires de modulation du signal SHG sur ces films. Nous souhaitons optimiser toutes les composantes du processus afin de déterminer le potentiel de ces composés en stockage optique de données.The development of new technologies , computer and internet in recent decades has been accompanied by an increasing demand for media storage information. In particular , the optical data storage .Conventional media ( CD-ROM , Blu-ray ... ) based on a storage disk surface, have now reached their limits. A new technology being developed , based on a data storage in three dimensions, is a promising alternative to replace conventional materials. Materials must include entities for photochromic properties (molecular switch) and multi- photon absorption demonstrated. In this thesis , we considered the synthesis of functional molecules which present these two characteristics. As a first step , we are interested in the synthesis and comparative study of homo and heteroleptic ruthenium complex having a certain potential for two-photon absorption . We have shown that these systems were very active and they allowed to host a photochromic entity lossless bi- photonic properties. We then studied the properties of originals photochromic ruthenium tris- bipyridine containing an azobenzene motif. The metal complexing profoundly changes the photochromism of azobenzene with significantly different from those ligands kinetics . Finally, we studied the properties of hybrid complexes of ligands for the two-photon absorption and others to photochromism , these compounds are active in both areas. We finally discuss the potential of the optical behavior of compounds of these complex films. We conducted preliminary tests of the SHG signal modulation on these films. We want to maximize all components of the process to determine the potential of these compounds in optical data storage