Elaboration and structural studies of cyclo 1:1-[α/α-N-amino]mers

International audienceIn order to investigate the ability of self-organization of the alternance of α-amino and α-N-amino-acids the synthesis of cyclo 1:1-[α/α-N-amino]mers has been achieved by an iterative sequence of deprotection and coupling reactions followed by a macrocyclization step. The self-assembling of N-amino deprotected cyclo-oligomers has been characterized using X-ray diffraction experiments and FT-IR analysis

New C-terminal hydrazide L-Leucine derivatives as multi-solvent low molecular weight organogelators

International audienceThree new low-molecular-weight gelators (LMWGs) based on L-Leucine derivatives bearing different chain lengths (i.e. 9, 12 or 16) were designed and synthesized. The N-terminal carries various alkyl chain lengths while the C-terminal is modified with hydrazide moiety. The prepared gelators 1-3 were fully characterized using 1 H, 13 C NMR, FTIR and mass spectroscopy. The gelation behavior has also been investigated using different organic solvents and oils with determination of critical gelation concentration (CGC). The self-assembly process was investigated by recording FTIR spectra gel states to investigate the driving forces for gelation process. The morphology of the prepared xerogels was studied using SEM

Preparation of polysaccharide-coated nanoparticles by emulsion polymerization of styrene

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Solid-Phase Synthesis of 4-methylcarboxy-1,4-benzodiazepine-2,5-diones

International audienceA solid-phase synthesis of 1,4-benzodiazepinone-2,5-diones is described. This new route can afford benzodiazepinone bearing a N-urethane-protected amine and a carboxylic acid function. This kind of building block is valuable as a dipeptide mimic or beta-turn mimetic, and it can be introduced in place of any amino acid in peptide synthesis. Using an "analytical probe" strategy, we optimized the synthesis of a model compound on SynPhase Lanterns. Therefore, the efficiency of several linkers was investigate

Synthesis and conformational studies of short mixed γ/α-glycopeptides based on sugar γ 3,3 -amino acids

International audienceCarbohydrates bearing both amino and carboxylate groups could be useful for expanding the repertoire of monomers used for building foldamers. In this paper, we give a full account of the synthesis of small hybrid g/a-glycopeptides built with sugar g-amino acids and L-alanine. The g/a-glycopeptides obtained are the first featuring geminally b,b-disubstituted g-amino acids in which the b-carbon is the pseudo anomeric carbon of a sugar ring. Their conformational properties were studied by NMR and solution infrared spectroscopy, circular dichroism and molecular dynamics simulation

Conformational studies of new pseudotripeptide with pyrazine amidoxime motif and simplified analogs using IR, NMR spectroscopy, and molecular dynamic simulations

International audienceSolution structures of new pyrazine-based pseudotripeptide with amidoxime function and simplified pseudodipeptide analogs were determined by a combination of IR and NMR spectroscopic studies and molecular dynamic simulations using explicit chloroform as a solvent. It was found that proline-phenylalanine dipeptide residue and amidoxime moiety in o-position are essential for intramolec- ular hydrogen bonding including a seven-membered γ-turn formation. In addition, a cis/trans equilibrium study was pres- ent for prolyl amides in polar solvents (D2O and DMSO). A phenylalanine substituent was found to exhibit profound ef- fect on thermodynamic parameters in prolyl peptides. The presence of intramolecular hydrogen bonds dramatically in- creases the amount of trans isomer in non-hydrogen-bonding CHCl3 and significantly favor cis isomer in hydrogen-bonding solvents such as DMSO and D2O. All molecules are not cy- totoxic therefore they can be further studied in relation to potent biological activities

Cyclohexamer [-( D -Phe-azaPhe-Ala) 2 -]: good candidate to formulate supramolecular organogels

International audienceMolecular self-assembly is a fascinating process which has become an area of great interest insupramolecular chemistry, as it leads in certain cases to molecular gels. Organogels formulated from lowmolecular weight compounds (LMWOGs) have attracted much interest in the past decades due to theirapplications as new soft materials. Herein, we report on the ability of the cyclic pseudopeptide cyclo-[-(D-Phe-azaPhe-Ala)2-] (2) to self-assemble in some aromatic solvents and to form organogels drivenby non-covalent forces, mainly hydrogen bonding and p-stacking interactions. Comprehensive FTIR andNMR studies emphasized that this cyclic aza-peptide adopts a b-turn conformation at low concentrationin toluene, while an equilibrium between the monomeric states (intramolecular forces) and thesupramolecular structures (intra- and intermolecular forces) is established at high concentration (gelstate). Rheological investigations of the organogels highlight the dependence of their stiffness (up to 4kPa) and sol/gel transition temperatures (up to 100 C) as a function of the solvent and concentration ofgelator used. The formulation of fibrous structures confirmed the phenomenon of self-assembly. Finally,we found that cyclo-[-(D-Phe-azaPhe-Ala)2-] is an effective organogelator for application in phaseselective gelation (PSG) of organic solvents from aqueous/organic mixtures with recovery percents up to96%

Improving and fine-tuning the properties of peptide-based hydrogels via incorporation of peptide nucleic acids

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Robust Helix Formation in a New Family of Oligoureas Based on a Constrained Bicyclic Building Block

International audienceThe field of foldamers has become an important area of chemistry over the years because of the particular structural and functional properties that foldamers display. The design, structural properties, and activities of different families of foldamers, including aromatic polyamides or structures closely related to peptides such as peptoids, b-peptides, and g-peptides, have been exhaustively reviewed.[1–8] Among the foldamers based on natural peptide sequences, b-peptides are the most widely studied system. In this system, cyclic b-amino acids are used as building blocks, allowing stabilization of various secondary structures in oligomers by strongly pro- moting gauche-type torsion angles.[3,9–12] Our group has recently described a highly constrained bicyclic b-amino acid, named (S)-ABOC 1, (S)-aminobicyclo[2.2.2]octane-2- carboxylic acid (Figure 1).[13] This b2,3,3-trisubstituted bicyclic amino acid, able to induce a turn in peptides both in solution and in the solid state,[14] displays drastically reduced con- formational freedom and a q1 angle locked at approximately 558. Therefore, this motif is particularly attractive for the design of new foldamers. To stabilize the helical system, other parameters should be considered. Indeed, Guichard and co- workers[15,16] provided a useful tool by introducing urea linkages for oligourea foldamers that are g-peptide mimet- ics.[17, 18] The presence of additional nitrogen atoms in the urea linkage promotes helix stabilization by introducing additional conformational restriction to the backbone and hydrogen- bond donor sites

Molecular modeling study for a novel structured oligomer subunit selection: the example of 2-aminomethyl-phenyl-acetic acid

International audienceOligomers derived from dipeptide mimics were selected by computational study for their suitability to fold in ordered structures. After selection of a monomeric unit, short oligomers were synthesized and analyzed by NMR and IR. Oligomers built from 2-aminomethyl-phenyl-acetic acid were shown to adopt a helical structure stabilized by 10-membered ring hydrogen bond