Straightforward Synthesis of a Double-Lasso Macrocycle from a Nonsymmetrical [c2]Daisy Chain

International audienceThe straightforward synthesis of a double-lasso macrocycle from a nonsymmetrical [c2]daisy chain, using the copper(I)-catalyzed Huisgen alkyne azide 1,3-dipolar cycloaddition, is described. The preparation of the nonsymmetrical alkyne azide [c2]daisy chain precursor was realized in situ via the exchange of the monomers contained in both symmetrical alkyne and azide [c2]daisy chains and was followed by mass spectrometry

Comparison of LID versus CID activation modes in tandem mass spectrometry of peptides

International audienceWe report our contribution to the systematic investigation of peptide fragmentations performed on high-performance Tof equipement operating in MS and MS/MS modes, such as ESI-QqTof and MALDI-Tof/Tof intruments that are commonly available today in proteomic laboratories. Whereas the former analyzer's configuration provides low-energy collision-induced dissociations (CID), the latter allows tunable activation methods of the selected parent ion to induce either metastable laser-induced dissociations (LID) or high-energy CID ('gas on spectra LID'). Fragmentation of the monoprotonated ion of 53 peptides (FW 807-2853 g/mol) was undertaken upon low-energy CID on an ESI-QT of mass spectrometer (Waters) as well as high-energy CID and LID conditions on a MALDI Ultraflex mass spectrometer (Bruker). Systematic comparison of MS/MS spectra provided useful information on the performance of each piece of equipment for efficient peptide sequencing and also insights into the observed fragmentation behaviors

Water transport in cement-in-polymer dispersions at variable temperature studied by magnetic resonance imaging

International audienceResol type resins were prepared in alkaline conditions (potassium hydroxide or potassium carbonate) using furfural obtained by acid hydrolysis of abundant renewable resources from agricultural and foresty waste residues. The structures of the resins were fully determined by 1H, 13C and 2D NMR spectrometries with the help of four models compounds synthesized specially for this stuudy MALDI-Tof mass spectrometry experiments indicated that a majority of linear oligomers and a minority of cyclic ones constituted them. Composites were prepared with furfural-phenol resins and sisal fibers. These fibers were chosen mainly because they came from natural lignocellulosic material and they presented excellent mechanical properties. Thermal analyses (dTG and DSC) and electron microscopy images indicated that the composites displayed excellent adhesion between resin and fibers. Impact strengh measurement showed that mild conditions were more suitable to prepare thermosets. Nevertheless, mild conditions induced a high-diffusion coefficient for water absorption by composites. Composites with good properties could be prepared using high proportion of materials obtained from biomass without formaldehyde