Mesoporous zirconosilicate doughnuts with high performance in liquid oxidative dehydrogenation of hydroquinone to quinone

Unusual partially crystalline ordered mesoporous zirconosilicate doughnuts with Si/Zr ratio as low as 1.5 were synthesized from the aqueous polymerisation of a single source molecular precursor Zr[OSi(Ot-BuO)(3)](4) without the use of any templating agent. A radial homogenous mesoporosity (4 nm) was observed inside these very regular sub-micrometric (600 nm) doughnuts. These structures were partially crystallized in hydrothermal conditions (100°C) into an analogous zircon (ZrSiO(4)) framework. The formation mechanism has been investigated. It is evidenced that chlorine anions Cl(-) concentration and pH value are essential to achieve the process, even if their role is still a matter of investigations. The obtained materials demonstrated even higher catalytic activity, selectivity and stability in the liquid oxidative dehydrogenation of hydroquinone to 1,4-benzoquinone compared to TS-1 zeolite catalysts and amorphous highly ordered mesoporous zirconosilicate materials.     

Evidence for a trianion intermediate in the metalation of 4-hydroxy-6,7-dimethoxy-8-methyl-2-naphthoic acid. Methodology and application to racemic 5,5'-didesisopropyl-5,5'-dialkylapogossypol derivatives

The metalation of 4-hydroxy-6,7-dimethoxy-8-methyl-2-naphthoic acid (8) affording trianion 6 is presented and applied to the regioselective efficient construction of a series of 5,5'-didesisopropyl-5,5'-dialkylapogossypol derivatives 3 that are potent pan-active inhibitors of antiapoptotic Bcl-2 family proteins.     

A platinum Chugaev carbene complex as a potent anticancer agent

A platinum Chugaev complex was synthesised and fully characterized by multinuclear NMR spectroscopy and X-ray crystallography. This cis bis acyclic diamino carbene complex acts as a cytotoxic compound and behaves as a cisplatin equivalent by interacting with supercoiled DNA and thiols. Stability of the ligand is also discussed.     

Metaheuristics for multiobjective optimisation

This is a summary of the author’s PhD thesis supervised by Laetitia Jourdan and El-Ghazali Talbi and defended on 8 December 2009 at the Université Lille 1. The thesis is written in French and is available from . This work deals with the design, implementation and experimental analysis of metaheuristics for solving multiobjective optimisation problems, with a particular interest on hard and large combinatorial problems from the field of logistics. After focusing on a unified view of multiobjective metaheuristics, we propose new cooperative, adaptive and parallel approaches. The performance of these methods are experimented on a scheduling and a routing problem involving two or three objective functions. We finally discuss how to adapt such metaheuristics during the search process in order to handle uncertainty that may occur from many different sources.     

High-harmonic generation from plasma mirrors at kilohertz repetition rate

We report the first demonstration of high-harmonic generation from plasma mirrors at a 1 kHz repetition rate. Harmonics up to nineteenth order are generated at peak intensities close to 101? W/cm2 by focusing 1 mJ, 25 fs laser pulses down to 1.7 μm FWHM spot size without any prior wavefront correction onto a moving target. We minimize target surface motion with respect to the laser focus using online interferometry to ensure reproducible interaction conditions for every shot and record data at 1 kHz with unprecedented statistics. This allows us to unambiguously identify coherent wake emission as the main generation mechanism.     

Cytosine: para-sulphonato-calix[4]arene assemblies: in solution, in the solid-state and on the surface of hybrid silver nanoparticles

The molecular recognition by para-sulphonato-calix[4]arene of cytosine, occurs in solution, in the solid-state and by assembly on the surface of para-sulphonato-calix[4]arene capped silver nanoparticles. Each of these states shows different modes of assembly; in solution a 1:1 complex is formed; in the solid state a 4:1 assembly exists, however some of the cytosine molecules are present as space fillers and do not participate in the host (guest complexes, finally on the surface of the hybrid silver/para-sulphonato-calix[4]arene nanoparticles a 2:1 cytosine/para-sulphonato-calix[4]arene assembly is observed. The assembly processes have been studied by DOSY NMR, fluorescence spectroscopy, Dynamic Light Scattering (DLS), Single Crystal Solid State Diffraction, Visible Spectroscopy and Electron Microscopy. The results demonstrate how cytosine initiates the aggregation of the hybrid silver/para-sulphonato-calix[4]arene hybrid nanoparticles.     

Gradient elution method in centrifugal partition chromatography for the separation of a complex sophorolipid mixture obtained from Candida bombicola yeasts

Sophorolipids represent an important class of natural surfactants with a variety of environmental, cosmetic, and pharmaceutical applications. Despite their promising physicochemical and biological properties, the use of sophorolipids is hampered by the lack of information regarding their individual structure‐activity relationships. The major difficulty in isolating pure sophorolipids arises from the high complexity of crude fermentation media composition and from their strong structural similarities. In this work, a centrifugal partition chromatography method was developed in an original gradient elution mode for the separation of sophorolipids produced by the yeast Candida bombicola. Experiments were realized by using three sets of solvent systems composed of n‐heptane, ethyl acetate, n‐butanol, methanol, and water in different proportions. The separation was performed at 5 mL/min in the ascending mode by increasing progressively the polarity of the organic mobile phase. In these conditions, more than 80% of the sophorolipids present in the initial crude fermentation extract were eluted successively from the most hydrophobic lactone forms to the most hydrophilic acid forms. The structures of the isolated sophorolipids were further elucidated by HPLC and NMR analyses.     

Studies of Radical Alternating Copolymerization. I. Quantitative Determination of the Relative Reactivities between Free Comonomers and a Complex between Them; A Theoretical Treatment in Terms of Frontier Molecular Orbital Interactions. Application to Radical Maleic Anhydride-Vinyl Acetate Alternating Copolymerization

A simple quantitative determination of the ratio β₁ of rate constants k_ij corresponding to the addition of a complex or a free monomer on a same growing chain in alternating copolymerization was determined. The application of this method to the case of alternating maleic anhydride (A)-vinyl acetate (D) copolymerization give for β₁ = k_AC/k_AD and for β₂ = k_DC/k_DA (C refers to the complex) the respective values of 7 and 0. A complex was more reactive than A but less reactive than D toward a growing chain. In order to explain these reactivities, a frontier molecular orbital treatment was proposed. A good qualitative correlation with experimental results was obtained.     

Vacuum Ultraviolet Action Spectroscopy of Polysaccharides

We studied the optical properties of gas-phase polysaccharides (maltose, maltotetraose, and maltohexaose) ions by action spectroscopy using the coupling between a quadrupole ion trap and a vacuum ultraviolet (VUV) beamline at the SOLEIL synchrotron radiation facility (France) in the 7 to 18 eV range. The spectra provide unique benchmarks for evaluation of theoretical data on electronic transitions of model carbohydrates in the VUV range. The effects of the nature of the charge held by polysaccharide ions on the relaxation processes were also explored. Finally the effect of isomerization of polysaccharides (with melezitose and raffinose) on their photofragmentation with VUV photons is presented.

New Advances in the Synthesis of Emerging Cyclic Amidrazones to Foster Bioisosterism of Azaheterocycles

The pace and the scope of new molecules design is often constrained by limitations in synthetic chemistry. The azaheterocyclic amidrazones are of particular interest for bioisosteric considerations in drug discovery. However, the lack of efficient synthetic access has undoubtedly hampered their occurrence in the drug chemical space. Our current results describe a robust synthetic access relying on cyclization of aminohydrazine in presence of various orthoesters by either metal free- or metal-catalyzed condensations. This optimized synthetic access to cyclic amidrazones as original scaffold should inspire the chemist community and further drive innovation in the design of molecular structure for many applications (for example, drugs, materials, dyes).