CNRS Separative Sciences and Methods

Rouen, France

CNRS Separative Sciences and Methods

Rouen, France
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Mendoza-Palomares C.,French Institute of Health and Medical Research | Mendoza-Palomares C.,University of Strasbourg | Ferrand A.,French Institute of Health and Medical Research | Ferrand A.,French National Center for Scientific Research | And 10 more authors.
ACS Nano | Year: 2012

Figure Persented: Nanobiotechnology enables the emergence of entirely new classes of bioactive devices intended for targeted intracellular delivery for more efficacies and less toxicities. Among organic and inorganic approaches currently developed, controlled release from polymer matrices promises utmost clinical impact. Here, a unique nanotechnology strategy is used to entrap, protect, and stabilize therapeutic agents into polymer coatings acting as nanoreservoirs enrobing nanofibers of implantable membranes. Upon contact with cells, therapeutic agents become available through enzymatic degradation of the nanoreservoirs. As cells grow, divide, and infiltrate deeper into the porous membrane, they trigger slow and progressive release of therapeutic agents that, in turn, stimulate further cell proliferation. This constitutes the first instance of a smart living nanostructured hybrid membrane for regenerative medicine. The cell contact-dependent bioerodable nanoreservoirs described here will permit sustained release of drugs, genes, growth factors, etc., opening a general route to the design of sophisticated cell-therapy implants capable of robust and durable regeneration of a broad variety of tissues. © 2011 American Chemical Society.


Galeta J.,Masaryk University | Man S.,Masaryk University | Bouillon J.-P.,CNRS Separative Sciences and Methods | Potaacek M.,Masaryk University
European Journal of Organic Chemistry | Year: 2011

Thermally initiated cycloaddition reactions of nonsymmetrical allenyl azines 1 with alkynes or other dipolarophiles usually lead to compounds with three fused, five-membered heterocyclic rings. With alkynes with pronounced "push-pull" systems, however, the reaction ends with the formation of substituted pyrrolidino[1,2-b]pyrazoles 4 and, in the case of azines with trifluoromethyl substitution, ring opening leads to the isolation of compounds 9. Reaction mechanisms for these transformations are proposed. The molecular structures of the new heterocycles 4 and 9 were confirmed by X-ray crystal structure analysis. Six alkynes A-F were reacted with four nonsymmetrical allenyl aldoketazines 1a-d in combined intra-intermolecular criss-cross cycloaddition reactions to afford compounds 2 (with alkynes A-D), and newfused bicyclic heterocycles 4 and 9 (withalkynes E and F). The new pyrrolidino[1,2-b]pyrazoles 4 are structurally related to the biologically active alkaloid withasomnine. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Allous I.,CNRS Organic and Macromolecular Chemistry Research Unit | Allous I.,Damascus University | Comesse S.,CNRS Organic and Macromolecular Chemistry Research Unit | Sanselme M.,CNRS Separative Sciences and Methods | Daich A.,CNRS Organic and Macromolecular Chemistry Research Unit
European Journal of Organic Chemistry | Year: 2011

Herein, we present a new development of the previously described aza-Michael-initiated ring closure (MIRC) process to access spirooxindole cores. The key spiro-cyclization step between various α-bromoacetamides and methyleneindolinones was efficient and tolerant of a wide range of functional groups. Yields and diastereoselectivities for the spirocyclization were usually high and furnished original spiro[oxindole-3,3′-γ-lactam] derivatives. The utility of these novel building blocks for the preparation of more sophisticated derivatives was demonstrated by the preparation of four pentacyclic spirooxindoles. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Semard G.,Cirsee Center International Of Recherche Sur Leau Et Lenvironnement | Semard G.,CNRS Separative Sciences and Methods | Peulon-Agasse V.,CNRS Separative Sciences and Methods | Bruchet A.,Cirsee Center International Of Recherche Sur Leau Et Lenvironnement | And 2 more authors.
Journal of Chromatography A | Year: 2010

It is important to develop methods of optimizing the selection of column sets and operating conditions for comprehensive two-dimensional gas chromatography. A new method for the calculation of the percentage of separation space used was developed using Delaunay's triangulation algorithms (convex hull). This approach was compared with an existing method and showed better precision and accuracy. It was successfully applied to the selection of the most convenient column set and the geometrical parameters of second column for the analysis of 49 target compounds in wastewater. © 2010 Elsevier B.V.


Clevers S.,CNRS Separative Sciences and Methods | Simon F.,CNRS Separative Sciences and Methods | Sanselme M.,CNRS Separative Sciences and Methods | Dupray V.,CNRS Separative Sciences and Methods | Coquerel G.,CNRS Separative Sciences and Methods
Crystal Growth and Design | Year: 2013

Temperature-resolved second harmonic generation (TR-SHG) and SHG microscopy were used to study under normal pressure the solid-solid transition mechanism occurring between the two monotropically related polymorphic forms (metastable Pna21 and stable P21/n) of 3-hydroxybenzoic acid (MHBA). The activation energy Ea (as a measure of the barrier energy) of the irreversible transition was determined via isothermal TR-SHG (137-144 kJ·mol-1). It fits well with that determined from differential scanning calorimetry (139 kJ·mol-1). Regarding the two crystal structures, optical microscopy observations, and kinetics parameters from TR-SHG, a destructive/reconstructive mechanism is proposed for the solid-solid transition. The present study clearly demonstrates that TR-SHG is a relevant and accurate technique for monitoring solid-solid phase transitions. © 2013 American Chemical Society.


Levilain G.,CNRS Separative Sciences and Methods | Coquerel G.,CNRS Separative Sciences and Methods
CrystEngComm | Year: 2010

The mirror symmetry relationship between enantiomers makes their separations by 'classical' separation methods difficult. When applicable, preferential crystallization is a productive and cost effective process which consists of alternate crystallizations of both enantiomers crystallizing as a conglomerate. Addition of in situ racemization to 'classical' preferential crystallization allows the yield to increase up to 100% in a single batch operation. Furthermore, the implementation of continuous 'gentle' grinding can solve the main problem of this method, i.e. the nucleation of the counter enantiomer. Preferential crystallization methodology can be also applied to any system composed of non symmetrical species. However, a set of thermodynamic and kinetic parameters must be determined for every compound that is supposed to crystallize selectively. This 'highlight' details the basic principles and the limitations of 'classical' preferential crystallization and its applications on 'exotic' systems by an extensive usage of phase diagrams. © 2010 The Royal Society of Chemistry.


Clevers S.,CNRS Separative Sciences and Methods | Simon F.,CNRS Separative Sciences and Methods | Dupray V.,CNRS Separative Sciences and Methods | Coquerel G.,CNRS Separative Sciences and Methods
Journal of Thermal Analysis and Calorimetry | Year: 2013

We report the use of second harmonic generation (SHG) and temperature resolved second harmonic generation (TR-SHG) for in situ probing and monitoring the structural purification of m-hydroxybenzoic acid (MHBA). Pure and mixtures of the two polymorphic forms of MHBA (metastable Pna21 and stable P21/c) and commercial MHBA were analysed by: DSC, XRPD and SHG. Results obtained with these three techniques are compared and demonstrate for that particular component, the high sensitivity and accuracy of SHG in assessing the polymorphic purity of MHBA. The SHG detection threshold for the metastable polymorph is circa 2 ppm and is several orders of magnitude better than the sensitivity of XRPD (1 wt%) and DSC (only 17 wt%). The proportion of the metastable phase in the commercial MHBA was evaluated to 1 wt% by SHG. Results of TR-SHG measurements performed on commercial MHBA at 5 K min-1 heating rate show that TR-SHG is a good technique for an in situ monitoring of the structural purity. The present study clearly demonstrates that SHG and TR-SHG are relevant and accurate techniques for probing the structural purity and for the monitoring of solid-solid phase transitions provided one of the two varieties crystallizes in a non-centrosymmetric space group. © 2012 Akadémiai Kiadó, Budapest, Hungary.


Amharar Y.,CNRS Separative Sciences and Methods | Petit S.,CNRS Separative Sciences and Methods | Sanselme M.,CNRS Separative Sciences and Methods | Cartigny Y.,CNRS Separative Sciences and Methods | And 2 more authors.
Crystal Growth and Design | Year: 2011

(±) 5-Methyl-5-(4′-ethylphenyl) hydantoin (18H) crystallizes in usual organic solvents as a conglomerate in the P212 121 space group. A new monohydrated racemic compound of 18H could however be obtained by antisolvent induced crystallization. The structure of this first hydrate of a hydantoin was successfully resolved by single crystal X-ray diffraction. It crystallizes in space group P2 1/c, and the crystal packing shows an association of homochiral molecular ribbons resulting from strong hydrogen bonds involving the water molecule and the hydantoin rings. At 30 °C and under low relative humidity (in the range 0-30%), the monohydrate exhibits an efflorescent behavior, with a reversible evolution toward a metastable anhydrous racemic phase through a cooperative zip-like mechanism. But under specific conditions (40-60% R.H., 30 °C), dehydration also leads to the nucleation and growth of the stable conglomerate, as confirmed by dynamic vapor sorption and X-ray powder diffraction analyses. The detailed analyses of solid-solid transformations between a hydrated racemic phase, an anhydrous racemic phase, and/or two anhydrous enantiomerically pure phases provide an opportunity to investigate examples of chiral recognition mechanisms in the solid state. The way the water molecules are released from the racemic monohydrate at 30 °C plays a decisive role in the nucleation and growth of the conglomerate. © 2011 American Chemical Society.


Martins D.,CNRS Separative Sciences and Methods | Stelzer T.,Martin Luther University of Halle Wittenberg | Ulrich J.,Martin Luther University of Halle Wittenberg | Coquerel G.,CNRS Separative Sciences and Methods
Crystal Growth and Design | Year: 2011

This work presents an original general route to obtain faceted tubular organic crystals (of several tens of micrometers in section) by putting the compound inside a thermal gradient. These hollow whiskers grow spontaneously when the thermal gradient exceeds a certain threshold, the highest temperature being close to the melting point, the lowest temperature being RT. This phenomenon could be explained by heat dissipation and transport of matter thanks to sublimation mechanisms and/or capillarity, i.e. by convective heat transfer. The open system is characterized by energy transport, entropy creation and spontaneous apparition of anisotropy. That is the reason why these hollow whiskers can be considered as relics of dissipative structures (Prigogine, I.Wiley: New York, 1967). © 2011 American Chemical Society.


Gonella S.,CNRS Separative Sciences and Methods | Mahieux J.,CNRS Separative Sciences and Methods | Sanselme M.,CNRS Separative Sciences and Methods | Coquerel G.,CNRS Separative Sciences and Methods
Organic Process Research and Development | Year: 2012

Nowadays the detection of conglomerates has been improved; but with a view to implement an efficient preparative resolution by preferential crystallization, this is not enough. Indeed, when a conglomerate has been spotted, there is no other way to assess the feasibility of its preferential crystallization than to run various tests of entrainment. Three similar molecular structures in the series of 1,2-diaminocyclohexyl derivatives are presented in this work. The structures correspond to conglomerates with nonobvious stoichiometry. Two are successfully resolved by preferential crystallization; the third one cannot be resolved by entrainment. © 2011 American Chemical Society.

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