Photoprocessing of Organic Material on Ceres: Laboratory Studies on Chemical Evolution of the Inner Dwarf Planet

Ceres is the largest object of the Solar System main belt with a complex geological and chemical history, which experienced extensive water related processes and geochemical differentiation. Ceres' surface is characterized by dark materials, phyllosilicates, ammonium-bearing minerals, carbonates, water ice, and salts. In addition to a global presence of carbon-bearing chemistry, local concentration of aliphatic organics has been detected by Dawn mission. The mission, thanks to the data collected by the Italian instrument VIR, showed clear evidence of a high amount of aliphatic organic material on the surface of Ceres. This has raised new questions about the origin and preservation of this material, especially when considering its high estimated abundance. We started a series of laboratory studies on physicochemical evolution of organic material interacting with minerals thought to be present on Ceres. The goal is to understand the transformations induced on these samples by processing with ultraviolet radiation

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Mechanistic investigations and development of Rh(II)-catalyzed [3+6+3+6] macrocyclization reactions

In 2010 the group of Professor Jérôme Lacour disclosed a new [3+6+3+6] reactivity leading to the formation of macrocyclic structures, closely related to 18C6 crown ethers. This reaction was achieved using a combination of alpha-diazo-beta-ketoesters reagents, 6-membered cyclic ethers and Rh(II) complexes as catalysts. The project of this PhD thesis was to disclose the kinetic and mechanistic parameters governing the formation of these macrocyclic structures and to optimize the process to readily scale up the reactions with low catalyst loading. These conditions were then applied on nitrogen containing substrates which were challenging at the time, such as morpholines. Moreover, an in-depth analysis of the key reaction parameters will be provided, with a focus on the role of the dirhodium catalysts and the diazo decomposition kinetics. The studies were also dedicated to an extensive analysis of the mechanism generating the macrocyclic structures, with a particular care on the characterization (reactivity and structure) of key oxonium ylide intermediate. Several achiral dirhodium complexes were synthetized, structurally analyzed, and applied in the reaction, showing, for some of them, such as novel Rh2(TCPTCC)4, a better catalytic activity. A scale up process (20 g of diazo) with a catalyst loading as low as 0.001 mol% was then generalized to increase the scope of the reaction. Challenging substrates such as protected morpholines were successfully used, generating aza-polyether macrocycles

FUNCTIONALIZED POLYETHER MACROCYCLIC COMPOUNDS AND USE THEREOF AS LUMINESCENT MARKERS

The invention relates to chiral enantioenriched functionalized polyether macrocyclic compounds displaying bright circularly polarized light emission and use thereof as luminescent markers

Kinetics of Rh(II)-Catalyzed α-Diazo-β-ketoester Decomposition and Application to the [3+6+3+6] Synthesis of Macrocycles on Large Scale and Low Catalyst Loadings

In the context of [3+6+3+6] macrocyclization reactions, precise kinetics of α-diazo-β-ketoester decomposition were measured by in situ infrared (IR) monitoring. Dirhodium complexes of Ikegami–Hashimoto type—and perchlorinated phthalimido derivatives in particular—performed better than classical achiral complexes. Clear correlations were found between speciation among dirhodium species and catalytic activity. With these results, novel cyclohexyl-derived catalysts were developed, affording good yields of macrocycles (up to 78%), at low catalyst loadings (from 0.01 mol % to 0.001 mol %) and on a large scale (from 1 g to 20 g)

One-Step Synthesis of Diaza Macrocycles by Rh(II)-Catalyzed [3 + 6 + 3 + 6] Condensations of Morpholines and α-Diazo-β-ketoesters

Selective formation of oxonium ylides from morpholines and α-diazo-β-ketoesters was achieved. This was applied to the high-concentration (0.5 M) dirhodium-catalyzed (0.1 mol %) [3 + 6 + 3 + 6] synthesis of 18-membered ring diaza macrocycles (46%–72%). Late-stage functionalization of these derivatives is demonstrated. Mechanistic evidence for a novel (undesired) diazo decomposition pathway is also reported

Building large supramolecular nanocapsules with europium cations

International audienceA new tripodal ligand has been designed by connecting pyridine-based coordination units to a rigid triptycene moiety. Its reaction with europium(III) provides three-dimensional tetranuclear edifices, whose structural and photophysical characteristics as well as host-guest interactions are discussed in this contribution

Formation of quaternary stereogenic centers by NHC-Cu-catalyzed asymmetric conjugate addition reactions with Grignard reagents on polyconjugated cyclic enones.

International audienceThe copper-catalyzed conjugate addition of various Grignard reagents to polyconjugated enones (dienone and enynone derivatives) is reported. The catalyst system, composed of copper triflate and an NHC ligand, led to the unusual selective formation of the 1,4-addition products. This reaction allows for the creation of all-carbon chiral quaternary centers with enantiomeric excesses up to 99%. The remaining unsaturation on the 1,4 adducts give access to valuable synthetic transformations