Self-interrupted synthesis of sterically hindered aliphatic polyamide dendrimers

Hydrolytically and enzymatically stable nanoscale synthetic constructs, with well-defined structures that exhibit antimicrobial activity, offer exciting possibilities for diverse applications in the emerging field of nanomedicine. Herein, we demonstrate that it is the core conformation, rather than periodicity, that ultimately controls the synthesis of sterically hindered aliphatic polyamide dendrimers. The latter self-interrupt at a predictable low generation number due to backfolding of their peripheral groups, which in turn leads to well-defined nanoarchitectures

Synthesis and conformational studies of linear and cyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mers

Ce travail décrit la synthèse et l'étude structurale de 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mères linéaires et cycliques. Après avoir mis au point une méthode générale de synthèse en solution des alpha-Nalpha-hydrazinoesters diversement substitués sur l'azote alpha, ces derniers ont été engagés dans l'élaboration de 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mères linéaires et cycliques de taille variable. Des études conformationnelles utilisant la RMN, l'IR et les RX ont permis de montrer que la présence de l'azote supplémentaire dans le squelette permettait l'établissement de liaisons hydrogène intramoléculaires conduisant à la formation d'hydrazinoturn. Ainsi l'alternance d'acides alpha-aminés naturels et d'alpha-hydrazinoacides conduit à une auto-structuration des oligomères linéaires par formation de y-turn et d'hydrazinoturn, identique en série hétéro- comme homochirale. En série cyclique, une analyse par RX a permis de mettre en évidence, à l'état solide, la formation de nanotubes due à l'empilement des cyclotétramères hétérochiraux. Cette conformation existe dans le toluène et le dodécane et conduit à la formation d'un gel. Bien que n'ayant pas de preuves de sa structure à l'état solide, le gel formé par le cyclohexamère hétérochiral dans le cyclohexane nous conforte dans l'idée d'une auto-structuration comparable. Les analyses RMN et IR en variation de concentration et température ont quant à elles mis en évidence la dynamique de formation des nanotubes. L'étude sur le cyclotétramère homochiral a cependant montré qu'il ne formait pas de gel. Le gel étant révélateur d'une auto-structuration, ceci nous conduit à nous interroger sur la versatilité du squelette macrocyclique 1:1-[alpha/alpha-Nalpha-Bn-hydrazino] pour l'établissement de nanotubesThis work describes the synthesis and the structural study of linear and cyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mers. After having designed a general method to synthesize alpha-Nalpha-hydrazinoesters with various surrogates on the alpha nitrogen in solution, these were used to build linear and cyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mers of varied length. Conformational studies resorting to NMR, IR and X-ray crystallography have shown that the presence of a supplementary nitrogen within the backbone enables to form intramolecular hydrogen bonds, leading to the formation of hydrazinoturns. Thus, the alternation of natural alpha-aminoacids and alpha-hydrazinoacids leads to the autostructuration of the linear oligomers through the formation of y-turns and hydrazinoturns, both in the hetero and homochiral series. In the cyclic series, an X-ray crystallography analysis revealed the formation of nanotubes in the solid state, through the stacking of heterochiral cyclotetramers. This conformation exists in toluene and dodecane and leads to the formation of a gel. Despite having no proof of its structure in the solid state, the gel formed by the heterochiral cyclohexamer in cyclohexane confirms a comparable auto-structuration. Finally, concentration- and temperature-dependant NMR and IR studies have revealed the dynamics of the formation of nanotubes. The study of the homochiral cyclotetramer has however shown that it was not able to form a gel. As the gel is indicative of an auto-structuration, this has led us to question the versatility of the macrocyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino] backbone towards the formation of nanotube

Synthèse et études conformationnelles de 1:1-[alpha-alpha-Nalpha-Bn-hydrazino]mères linéaires et cycliques

This work describes the synthesis and the structural study of linear and cyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mers. After having designed a general method to synthesize alpha-Nalpha-hydrazinoesters with various surrogates on the alpha nitrogen in solution, these were used to build linear and cyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mers of varied length. Conformational studies resorting to NMR, IR and X-ray crystallography have shown that the presence of a supplementary nitrogen within the backbone enables to form intramolecular hydrogen bonds, leading to the formation of hydrazinoturns. Thus, the alternation of natural alpha-aminoacids and alpha-hydrazinoacids leads to the autostructuration of the linear oligomers through the formation of y-turns and hydrazinoturns, both in the hetero and homochiral series. In the cyclic series, an X-ray crystallography analysis revealed the formation of nanotubes in the solid state, through the stacking of heterochiral cyclotetramers. This conformation exists in toluene and dodecane and leads to the formation of a gel. Despite having no proof of its structure in the solid state, the gel formed by the heterochiral cyclohexamer in cyclohexane confirms a comparable auto-structuration. Finally, concentration- and temperature-dependant NMR and IR studies have revealed the dynamics of the formation of nanotubes. The study of the homochiral cyclotetramer has however shown that it was not able to form a gel. As the gel is indicative of an auto-structuration, this has led us to question the versatility of the macrocyclic 1:1-[alpha/alpha-Nalpha-Bn-hydrazino] backbone towards the formation of nanotubesCe travail décrit la synthèse et l'étude structurale de 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mères linéaires et cycliques. Après avoir mis au point une méthode générale de synthèse en solution des alpha-Nalpha-hydrazinoesters diversement substitués sur l'azote alpha, ces derniers ont été engagés dans l'élaboration de 1:1-[alpha/alpha-Nalpha-Bn-hydrazino]mères linéaires et cycliques de taille variable. Des études conformationnelles utilisant la RMN, l'IR et les RX ont permis de montrer que la présence de l'azote supplémentaire dans le squelette permettait l'établissement de liaisons hydrogène intramoléculaires conduisant à la formation d'hydrazinoturn. Ainsi l'alternance d'acides alpha-aminés naturels et d'alpha-hydrazinoacides conduit à une auto-structuration des oligomères linéaires par formation de y-turn et d'hydrazinoturn, identique en série hétéro- comme homochirale. En série cyclique, une analyse par RX a permis de mettre en évidence, à l'état solide, la formation de nanotubes due à l'empilement des cyclotétramères hétérochiraux. Cette conformation existe dans le toluène et le dodécane et conduit à la formation d'un gel. Bien que n'ayant pas de preuves de sa structure à l'état solide, le gel formé par le cyclohexamère hétérochiral dans le cyclohexane nous conforte dans l'idée d'une auto-structuration comparable. Les analyses RMN et IR en variation de concentration et température ont quant à elles mis en évidence la dynamique de formation des nanotubes. L'étude sur le cyclotétramère homochiral a cependant montré qu'il ne formait pas de gel. Le gel étant révélateur d'une auto-structuration, ceci nous conduit à nous interroger sur la versatilité du squelette macrocyclique 1:1-[alpha/alpha-Nalpha-Bn-hydrazino] pour l'établissement de nanotube

Synthèse et études conformationnelles de 1:1-[a-a-Na-Bn-hydrazino]mères linéaires et cycliques

Ce travail décrit la synthèse et l'étude structurale de 1:1-[a/a-Na-Bn-hydrazino]mères linéaires et cycliques. Après avoir mis au point une méthode générale de synthèse en solution des a-Na-hydrazinoesters diversement substitués sur l'azote a, ces derniers ont été engagés dans l'élaboration de 1:1-[a/a-Na-Bn-hydrazino]mères linéaires et cycliques de taille variable. Des études conformationnelles utilisant la RMN, l'IR et les RX ont permis de montrer que la présence de l'azote supplémentaire dans le squelette permettait l'établissement de liaisons hydrogène intramoléculaires conduisant à la formation d'hydrazinoturn. Ainsi l'alternance d'acides a-aminés naturels et d'a-hydrazinoacides conduit à une auto-structuration des oligomères linéaires par formation de g-turn et d'hydrazinoturn, identique en série hétéro- comme homochirale. En série cyclique, une analyse par RX a permis de mettre en évidence, à l'état solide, la formation de nanotubes due à l'empilement des cyclotétramères hétérochiraux. Cette conformation existe dans le toluène et le dodécane et conduit à la formation d'un gel. Bien que n'ayant pas de preuves de sa structure à l'état solide, le gel formé par le cyclohexamère hétérochiral dans le cyclohexane nous conforte dans l'idée d'une auto-structuration comparable. Les analyses RMN et IR en variation de concentration et température ont quant à elles mis en évidence la dynamique de formation des nanotubes. L'étude sur le cyclotétramère homochiral a cependant montré qu'il ne formait pas de gel. Le gel étant révélateur d'une auto-structuration, ceci nous conduit à nous interroger sur la versatilité du squelette macrocyclique 1:1-[a/a-Na-Bn-hydrazino] pour l'établissement de nanotubesThis work describes the synthesis and the structural study of linear and cyclic 1:1-[a/a-Na-Bn-hydrazino]mers. After having designed a general method to synthesize a-Na-hydrazinoesters with various surrogates on the a nitrogen in solution, these were used to build linear and cyclic 1:1-[a/a-Na-Bn-hydrazino]mers of varied length. Conformational studies resorting to NMR, IR and X-ray crystallography have shown that the presence of a supplementary nitrogen within the backbone enables to form intramolecular hydrogen bonds, leading to the formation of hydrazinoturns. Thus, the alternation of natural a-aminoacids and a-hydrazinoacids leads to the autostructuration of the linear oligomers through the formation of g-turns and hydrazinoturns, both in the hetero and homochiral series. In the cyclic series, an X-ray crystallography analysis revealed the formation of nanotubes in the solid state, through the stacking of heterochiral cyclotetramers. This conformation exists in toluene and dodecane and leads to the formation of a gel. Despite having no proof of its structure in the solid state, the gel formed by the heterochiral cyclohexamer in cyclohexane confirms a comparable auto-structuration. Finally, concentration- and temperature-dependant NMR and IR studies have revealed the dynamics of the formation of nanotubes. The study of the homochiral cyclotetramer has however shown that it was not able to form a gel. As the gel is indicative of an auto-structuration, this has led us to question the versatility of the macrocyclic 1:1-[a/a-Na-Bn-hydrazino] backbone towards the formation of nanotubesMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Synthesis and Conformational Analysis of 1:1 [α/α- N α -Bn-Hydrazino] and 1:1 [α- N α -Bn-Hydrazino/α] Trimers: Determination of the Δ δ Value for the γ-Turn Structuration

International audienc

Evidence of Nanotubular Self-Organization in Solution and Solid States of Heterochiral Cyclo 1:1 [alpha/alpha-N-alpha-Bn-hydrazino]mers Series

International audienceThe cyclization of heterochiral 1:1 [alpha/alpha-N-alpha-Bn-hydrazino]mers leads to the corresponding cyclotetramer and cyclohexamer 3 and 4. X-ray crystallographic analysis of 3 unveils its ability to self-assemble into nanotubular structures. Further experiments conducted in the solid state through SEM analyses demonstrate the capability of 3 and 4 to form aerogels consisting of a network of nontwisted fibers, thus confirming the presence of self-organization within this series of mixed-hydrazinopeptides. Subsequent FTIR and NMR studies demonstrate the presence of an equilibrium between monomeric (intramolecular H-bonds) and nanotubular (intermolecular H-bonds) forms in solution. This equilibrium can be modified by varying the solvent

Self-Organization Ability of Chiral N α -Substituted, N β -Boc Protected α-Hydrazinoacetamides in the Crystal and Solution States

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Spontaneous Self-Assembly of Fully Protected Ester 1:1 [α/α- N α -Bn-hydrazino] Pseudodipeptides into a Twisted Parallel β-Sheet in the Crystal State

International audiencePrevious studies have, demonstrated that amidic alpha/beta-pseudodipeptides, 1:1 [alpha/alpha-N-alpha-Bn-hydrazino], have the ability to fold-via a succession of gamma-turn (C-7 pseudocycle) and hydrazinoturn in CDCl3 solution, their amide terminals enabling the formation of an intramolecular H-bond network. Despite their lack of a primary amide terminals allowing the formation of the hydrazinoturn, their ester counterparts 1-4 were proven to self-assemble into C-6 and C-7 pseudocycles by intramolecular H-bonds in solution state and into an uncommon twisted parallel beta-sheet through intermolecular H-bonding in the crystal state to form a supramolecular helix, with eight molecules needed to complete a full 360 degrees rotation. Such self organization (with eight molecules) has only been observed in a specific alpha/alpha-pseudodipeptide, depsipeptide (Boc-Leu-Lac-OEt). Relying on IR absorption, NMR, X-ray diffraction, and CD analyses, the aim of this study was to demonstrate that stereoisomers of ester 1:1 [alpha/alpha-N-alpha-Bn-hydrazino] pseudodipeptides 1-4 are able to self-assemble into this beta-helical structure. The absolute configuration of the asymmetric C-alpha-atom of the alpha-amino-acid residue influences the left-or right-handed twist without changing the pitch of the formed helix

Unraveling functional significance of natural variations of a human galectin by glycodendrimersomes with programmable glycan surface

Surface-presented glycans (complex carbohydrates) are docking sites for adhesion/growth-regulatory galectins within cell-cell/ matrix interactions. Alteration of the linker length in human galectin-8 and single-site mutation (F19Y) are used herein to illustrate the potential of glycodendrimersomes with programmable glycan displays as a model system to reveal the functional impact of natural sequence variations in trans recognition. Extension of the linker length slightly reduces lectin capacity as agglutinin and slows down aggregate formation at low ligand surface density. The mutant protein is considerably less active as agglutinin and less sensitive to low-level ligand presentation. The present results suggest that mimicking glycan complexity and microdomain occurrence on the glycodendrimersome surface can provide key insights into mechanisms to accomplish natural selectivity and specificity of lectins in structural and topological terms. adhesion | agglutination | glycobiology | membrane mimic | self-assembl

Evidence of Nanotubular Self-Organization in Solution and Solid States of Heterochiral Cyclo 1:1 [α/α‑<i>N</i>^α‑Bn-hydrazino]mers Series

The cyclization of heterochiral 1:1 [α/α-<i>N</i>^α-Bn-hydrazino]­mers leads to the corresponding cyclotetramer and cyclohexamer <b>3</b> and <b>4</b>. X-ray crystallographic analysis of <b>3</b> unveils its ability to self-assemble into nanotubular structures. Further experiments conducted in the solid state through SEM analyses demonstrate the capability of <b>3</b> and <b>4</b> to form aerogels consisting of a network of nontwisted fibers, thus confirming the presence of self-organization within this series of mixed-hydrazinopeptides. Subsequent FTIR and NMR studies demonstrate the presence of an equilibrium between monomeric (intramolecular H-bonds) and nanotubular (intermolecular H-bonds) forms in solution. This equilibrium can be modified by varying the solvent