Internal frequency conversion extreme ultraviolet interferometer using mutual coherence properties of two high-order-harmonic sources

International audienceWe report on an innovative two-dimensional imaging extreme ultraviolet (XUV) interferometer operating at 32 nm based on the mutual coherence of two laser high order harmonics (HOH) sources, separately generated in gas. We give the first evidence that the two mutually coherent HOH sources can be produced in two independent spatially separated gas jets, allowing for probing centimeter-sized objects. A magnification factor of 10 leads to a micron resolution associated with a subpicosecond temporal resolution. Single shot interferograms with a fringe visibility better than 30% are routinely produced. As a test of the XUV interferometer, we measure a maximum electronic density of 3×10^20 cm^−3 1.1 ns after the creation of a plasma on aluminum target

Chimie des métallophosphonates appliquée à la biologie et à la catalyse

Cette thèse, située à l interface de la biologie et de la chimie, traite dans une première partie du développement d un nouveau concept pour la préparation de puce à ADNs doubles brins. L utilisation d un support de Langmuir-Blodgett à base de phosphonate de zirconium permet l ancrage d ADNs doubles brins à terminaisons phosphate via une liaison à caractère iono-covalente. Une étude a permis de montrer que l insertion d un espaceur à 9 motifs guanine entre la fonction d ancrage et la séquence, conduit à une meilleure sensibilité de la puce, liée à la formation en solution d un polyG quadruplex. De plus, une augmentation de fluorescence a été observée lors de l introduction de deux groupements phosphate sur le même brin. Suite à ces différentes observations, une série de mesures physiques a été entreprise pour tenter d expliquer la relation entre l efficacité de capture des sondes et la position des groupements phosphate. Dans la seconde partie de ce mémoire, une étude sur l influence de l hétérogénéisation de catalyseurs dérivés de la 2,2 -bipyridine et du salen de Jacobsen a été réalisée. Dans un premier temps, le développement d une stratégie de synthèse permettant l accès à des analogues phosphonate a été effectuée, suivie de leur immobilisation au sein d une matrice inorganique (oxyde de titane) ou sur film de Langmuir-Blodgett à base de phosphonate de zirconium. Ensuite, une évaluation de l activité catalytique de ces nouveaux matériaux nous a permis de mettre en évidence un phénomène de relation structure-activité en ce qui concerne l hydrogénation compétitive alcène/cétone catalysée par les complexes rhodium-2,2 -bipyridine supportésThe first part of this PhD thesis presents the development of a new concept for the preparation of dsDNA microarrays. The use of zirconium phosphonate Langmuir-Blodgett films allows the immobilization of double-stranded DNA modified with terminal phosphate groups via a iono-covalent coupling. It was shown that the introduction of a polyG spacer led to an increase of the sensitivity of the biochip due to the formation of polyG quadruplex structures. More importantly, the presence of phosphate linkers on both ends of the dsDNA probes leads to a significant enhancement of the target capture. The relevant characteristics of the different probes when bound to the surface were determined by the original use of a combination of surface characterization techniques (XPS, AFM and SARFUS). In the second part of this work, a study of the influence of the immobilization of phosphonate-derivatized 2,2 -bipyridine and Salen was performed. First, new synthetic routes for the preparation of these modified ligands were optimised. Then, the immobilisation of these new ligands onto in situ generated titanium oxide particles or onto zirconium phosphonate Langmuir-Blodgett films was developed. Finally, a comparison of supported rhodium-2,2 -bipyridine complexes with the parent homogeneous system for the hydrogenation of ketones and carbon-carbon double bonds under hydrogen pressure in alkaline methanol is givenNANTES-BU Sciences (441092104) / SudocSudocFranceF

(P,C)-Cyclometalated complexes deriving from naphthyl phosphines: versatile and powerful tools in organometallic chemistry

The chemistry of (P,C)-cyclometalated complexes deriving from naphthyl phosphines [ Np (P,C)M] is presented and analysed in this review. The three main synthetic approaches, namely P-chelation assisted C-H activation, oxidative addition and transmetalation, are described and compared. If the naphthyl framework inherently predisposes the phosphorus atom and transition metal to interact, the rigid metallacycle may induce some strain and distortion, as apparent from the survey of the single-crystal X-ray diffraction structures deposited in the Cambridge Structural Database (77 entries with metals from group 7 to 11). Generally, the Np (P,C)-cyclometalation imparts high thermal and chemical robustness to the complexes, and a variety of stoichiometric reactions have been reported. In most cases, the metalacyclic structure is retained, but protodecyclometalation and ring-expansion have been sparingly observed. [ Np (P,C)M] complexes have also proved to be competent and actually competitive catalysts in several transformations, and they act as key intermediates in some others. In addition, interesting phosphorescence properties have been occasionally pointed out

A SIMPLE In-BASED DUAL CATALYST ENABLES SIGNIFICANT PROGRESS IN ε- DECALACTONE RING-OPENING (CO)POLYMERIZATION

International audienceA dual catalyst associating InCl3 and triethylamine was found to promote controlled ring-opening polymerization of ε-decalactone (ε-DL), a monomer derived from sustainable resources. Polydecalactones (PDL) of well-defined structures with Mn up to 30 000 g/mol (Đ ~ 1.2) have been obtained free of catalytic residues under mild conditions (toluene, 3M, 60 °C, 1-20 h). Besides the typical ester end-capped PDLs, amide end groups have been installed thanks to the ability of the dual catalyst to perform with primary amines as initiators. Block PDL-b-PCL / PCL-b-PDL and random P(DL-r-CL) copolymers have been also prepared by sequential and simultaneous ROP with ε-caprolactone, respectively. The absence of undesirable 2 transesterifications reactions, as apparent from NMR, SEC, and DSC analyses, enable the preparation of well-defined copolymers

Ultrasounds welding of nanocellulosic materials

International audienceThe interest for cellulose nanocrystals and nanofibrils is exponentially increased since last decade thanks to their industrialization. In addition to their low density, high aspect ratio, high stiffness and Young’s modulus and chemically reactive surface, this material is well known for its high specific surface. Thanks to these particular properties, cellulose nanomaterials can be used within a wide variety of applications. Coating is one of the promising applications for nanocellulose mainly for barrier applications in packaging. Indeed new bio-based but also high performance solutions are expected in food packaging. Unfortunately, up to now, high barrier solutions can be provided but they always require a layer of thermosealing polymer which is usually fossil based. These multilayer materials are also more complicate to handle when end of life is considered. One solution would be to propose cellulosic materials which could be welded easily. Except thermosealing, ultrasounds welding have been developed in plastic industry last years.This study is a proof of concept that nanocellulosic materials can be welded by ultrasounds. Several nanocellulosic materials were firstly designed and characterized, i.e. from classic cellulose nanocrystals and nanofibrils to functionalized CNC by esterification with lauric acid. Than model films were prepared and welded by ultrasounds. Process parameters were optimized and successful welding were obtained and mechanically characterized. These very positive results have been patented and open the doors for new solutions in welding of biobased materials

Ultrasounds welding of nanocellulosic materials

International audienceThe interest for cellulose nanocrystals and nanofibrils is exponentially increased since last decade thanks to their industrialization. In addition to their low density, high aspect ratio, high stiffness and Young’s modulus and chemically reactive surface, this material is well known for its high specific surface. Thanks to these particular properties, cellulose nanomaterials can be used within a wide variety of applications. Coating is one of the promising applications for nanocellulose mainly for barrier applications in packaging. Indeed new bio-based but also high performance solutions are expected in food packaging. Unfortunately, up to now, high barrier solutions can be provided but they always require a layer of thermosealing polymer which is usually fossil based. These multilayer materials are also more complicate to handle when end of life is considered. One solution would be to propose cellulosic materials which could be welded easily. Except thermosealing, ultrasounds welding have been developed in plastic industry last years.This study is a proof of concept that nanocellulosic materials can be welded by ultrasounds. Several nanocellulosic materials were firstly designed and characterized, i.e. from classic cellulose nanocrystals and nanofibrils to functionalized CNC by esterification with lauric acid. Than model films were prepared and welded by ultrasounds. Process parameters were optimized and successful welding were obtained and mechanically characterized. These very positive results have been patented and open the doors for new solutions in welding of biobased materials

Metal-Ligand-Lewis Acid Multi-Cooperative Catalysis: A Step Forward in the Conia-Ene Reaction

International audienceAn original multi-cooperative catalytic approach was developed by combining metal-ligand cooperation and Lewis acid activation. The [(SCS)Pd]2 complex featuring a non-innocent indenediide-based ligand was found to be a very efficient and versatile catalyst for the Conia-Ene reaction, when associated with Mg(OTf)2. The reaction operates at low catalytic loadings under mild conditions with HFIP as co-solvent. It works with a variety of substrates, including those bearing internal alkynes. It displays complete 5-exo vs 6-endo regio-selectivity. In addition, except for the highly congested t Bu-substituent, the reaction occurs with high Z vs E stereo-selectivity, making it synthetically useful and complementary to known catalysts.

Valorization of CO2: Preparation of 2-Oxazolidinones by Metal-Ligand Cooperative Catalysis with SCS lndenediide Pd Complexes

bibtex: ISI:000398986700049 bibtex\location:'1155 16TH ST, NW, WASHINGTON, DC 20036 USA',publisher:'AMER CHEMICAL SOC',type:'Article',affiliation:'Martin-Vaca, B; Bourissou, D (Reprint Author), Univ Toulouse, CNRS, UMR 5069, UPS,LHFA, 118 Route Narbonne, F-31062 Toulouse, France. Brunel, Paul; Monot, Julien; Martin-Vaca, Blanca; Bourissou, Didier, Univ Toulouse, CNRS, UMR 5069, UPS,LHFA, 118 Route Narbonne, F-31062 Toulouse, France. Kefalidis, Christos E.; Maron, Laurent, Univ Toulouse, CNRS, UMR 5215, INSA,UPS,LPCNO, 135 Ave Rangueil, F-31400 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ER7IS','funding-acknowledgement':'Centre National de la Recherche Scientifique; Universite de Toulouse; Agence Nationale de la Recherche [ANR CE6-CYCLOOP]; COST Action [CM1205 CARISMA]','funding-text':'This manuscript is in memory of Prof. Jose Barluenga. This work was supported financially by the Centre National de la Recherche Scientifique, the Universite de Toulouse, the Agence Nationale de la Recherche (ANR CE6-CYCLOOP), and the COST Action CM1205 CARISMA (Catalytic Routines for Small Molecule Activation). The authors are grateful to CalMip (CNRS, Toulouse, France) for calculation facilities. L.M. thanks the Institut Universitaire de France. Dr. J. Babinot is acknowledged for the preparation of substrates 1j,k.','journal-iso':'ACS Catal.','keywords-plus':'PALLADIUM PINCER COMPLEXES; CARBON-DIOXIDE INCORPORATION; N BOND FORMATION; CARBOXYLATIVE CYCLIZATION; EFFICIENT SYNTHESIS; PROPARGYLIC AMINES; ACETYLENIC AMINES; ATMOSPHERIC CO2; C-N; IONIC LIQUIDS','number-of-cited-references':'73',oa:'Bronze','orcid-numbers':'Kefalidis, Christos/0000-0002-1380-4337 Bourissou, Didier/0000-0002-0249-1769','research-areas':'Chemistry','researcherid-numbers':'Kefalidis, Christos/G-1067-2012','times-cited':'19','unique-id':'ISI:000398986700049','usage-count-last-180-days':'10','usage-count-since-2013':'32','web-of-science-categories':'Chemistry, Physical'\The capture and utilization of CO, to prepare high value compounds is very attractive chemically and highly desirable socially. Indenediide-based Pd SCS pincer complexes are shown here to promote the carboxylative cyclization of propargylamines leading to 2-oxazolidinones under mild conditions (0.5-1 bar of CO2, DMSO, 40-80 degrees C, mol % Pd loading). The indenediide Pd complex is competitive with known catalysts. It proved successful for a wide range of propargylamines, including hitherto challenging substrates such as secondary propargylamines bearing tertiary alkyl groups at nitrogen, primary propargylamines, and propargylanilines. Thorough experimental (NMR) and computational (DFT) investigations were undertaken to gain mechanistic insights. Accordingly, (i) the resting state of the catalytic cycle is a Pd DMSO complex; (ii) the indenediide backbone and Pd center act in concert to activate the carbamic acid intermediate and promote its cyclization; (iii) proton shuttling is essential to lower the activation barriers of the initial amine carboxylation as well as of the proton transfers between the ligand backbone and the organic fragments at Pd