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A simple and efficient protocol for the preparation of a series of N-alkyl-3-boronopyridinium salts is described which requires exposure of 3-pyridineboronic acid neopentylglycol ester and corresponding alkyle halide to microwave irradiation followed by boronic ester hydrolysis. The technique employed drastically reduces the reaction time and prevents thermal degradation and the formation of side products. Water solutions of the obtained boronopyridinium salts are shown to be stable at room temperature in wide pH range as well as in the presence of hydrogen peroxide at pH 10.0 for 72 h.

In this paper, we describe a simple and efficient procedure of original N-alkyl-3-boronopyridinium triflates synthesis and report on the surface properties of these surfactants. Key micellar parameters were obtained, the critical micelle concentrations (CMC values) were determined and compared to conventional ionic surfactants as well as the surface activity of these surfactants (pC 20 value and the surface tension at the CMC). These new boronic functionalized surfactants exhibit a stunning efficiency in their tendency to self-assemble and are significantly more surface active that their conventional analogues. This new family of surfactants represents a new direction in both functionality and performance, and may open perspectives in chemical synthesis and applications.

Media are among the most important factors to be considered for organic synthesis in soft and non-polluting conditions satisfying the conditions for sustainable development. Organized Molecular Systems (OMS) are very useful when efforts are being made to apply the twelve green chemistry principles, more precisely to replace organic solvents, to carry out reactions in water, to employ catalysis and biocatalysis, to economize molecules (and, of course, of atoms) and to work with low-energy conditions. These OMS posses a number of advantages: solubilization of substances that are not normally soluble in the continuous phase of OMS, localization of reactants and products, and selective orientation and stabilization of the various entities in the various stages of the reaction. Rapid and selective reactions of preparative amounts of substrate can be carried out in such media, which are also very suitable for mechanistic studies. First, we performed organic photoreactions in microemulsions (macroscopically homogeneous and transparent media). Thus, we were able to confirm the interfacial localization of the processes by means of chemical internal sensors and infrared spectroscopy; to propose a formulation strategy for diminishing the number of substrates in the medium (molecular economy principle); and to use high interfacial concentration to carry out reactions in the liquid phase although they are generally only possible in the solid state. The most important scientific point was the demonstration of the generalization of the amphiphilicity concept, by using polar non-aqueous solvents. 1986 saw the end of a controversy concerning the use of formamide in place of water. With this type of solvent, we have been able to perform important reactions: the Wacker process, Diels-Alder reactions, and olefin amidations. Then we postulated the formation of aggregates without surfactants if differential solvations were operative. All organic reactions can be influenced by the spontaneous formation of aggregates. To finish, with such systems, it is possible to orientate the reactivity of competitive reactions (e.g. cyclization and polymerization) and help to protect the environment, for example in the synthesis of clean surfactants in clean conditions. With the extension of these observations and results to the use of rigid objects (similar to rigid micelles) we were able to obtain very high enantioselective excess in chiral processes.

Ionic liquids are green solvents with interesting properties: displaying low melting points and high boiling points. They offer a new approach applicable in many instances. Nevertheless, the presence of free ions can be a matter in some cases, e.g. for the study of nucleophilic reactions, in electrochemistry, and in each situation where there is a competition between counter ions, as in micellization of ionic surfactants. Neutral compounds having formal unit electrical charges of opposite sign, and the same physical properties than ionic liquids would be a nice alternative to these latter solvents. There are two classes of chemical compounds having these characteristics: zwitterionic liquids (with no uncharged canonical representation) and mesoionic liquids (in which the negative and the positive charges are delocalized). In that last class we have chosen to work with 3-methylsydnone in order to examine, in this aprotic solvent, if it was possible to observe aggregation of surfactants in the same manner as in water. With all kinds of surfactants studied (ionic, zwitterionic and mesoionic) we have been able to demonstrate the formation of direct micelles: hydrogen bonding is thus not mandatory for molecular aggregation. Comparison of the behavior in water and in formamide showed that solvophobic interactions were qualitatively comparable but with a lower intensity.

Adipic acid is an important industrial intermediate for the manufacture of nylon-6,6. We propose a recyclable and environmentally friendly process for the oxidation of cyclohexene by hydrogen peroxide in microemulsions. These organized nano-structured media have been formulated in using the molecular economy principle. The main interests of the present work are the easy recovery of pure adipic acid and the reuse of the reaction media, what are promising for developing a future green industrial process.

As part of a collaborative research project aimed at designing new chemicals active on mosquito larvae, we sought accessible raw materials and an efficient synthesis method for preparing large amounts of active substances. For this we selected retinoic acid, which has functionality close to that of juvenile hormones. From this molecule we developed ester and trifluoromethyl ketone synthesis that was fast and led to good yields.

The palladium (II) chloride catalyzed coupling reaction of N-alkylpyridiniumboronic acids with benzoic anhydride was carried out smoothly in water to give high yields of ketones without the use of a phosphine ligand. The reaction was conducted under mild conditions at room temperature. In this article, by focusing on the Suzuki reaction, it is shown how this method can impact modern synthetic chemistry, making reactions faster, easier and cleaner. Copyright © 2009 John Wiley & Sons, Ltd.

We have investigated the aggregation of surfactants in formamide (FA) instead of water. Qualitatively, the general behavior with FA is similar to the corresponding aqueous systems. Micelle formation has been demonstrated in this solvent as well as the formation of liquid crystalline mesophases at higher surfactant concentration. However, there were some quantitative differences, for example: the much higher Krafft temperature and critical micellar concentration (cmc) values with FA solvent compared to the aqueous systems, and the possibility to utilize amphiphilic molecules insoluble in water. Vesicles and liposomes have been observed, similar to those obtained in water. Also, in microemulsions, water may be replaced by formamide and such non-aqueous microemulsions are reaction media very efficient for organic synthetic processes.

In the course of our investigations of routes for general and convenient synthesis of amphiphiles derived from sugars, we reported new synthetic ways to prepare catanionic surfactants, polymers and dendrimers using unprotected lactose or lactobionic acid. Moreover we developed amphiphilic polymers and dendrimers bearing sugar polar heads. These compounds are of interest for their biological applications (mimics of natural ligands of proteins (e.g.: gp 120 of HIV), encapsulation, vectorization). To cite this article: I. Rico-Lattes et al., C. R. Chimie 8 (2005).

Resume L'epoxydation du RMN3, alcene mixte fluore–hydrogene de formule C8F17CH2CH=CH-iBu, conduit a l'epoxyde correspondant, avec des rendements allant jusqu'a 90%, selon la nature du ligand azote. Dans le cadre de cette etude, nous avons etudie l'influence de la bipyridine, substituee ou non, greffee avec des chaines fluorocarbonees ou hydrocarbonees ainsi que le positionnement de ces motifs sur les cycles pyridiniques. Pour citer cet article : A. Banu et al., C. R. Chimie 8 (2005).

A novel approach to the synthesis of molecularly imprinted polymers via covalent or non-covalent linkages was studied. It relies on the use of thermotropic side-chain liquid-crystal polymer networks. The polysiloxane networks obtained after extraction of the template preserved the mesomorphic organisation set up in the presence of the guest molecule. Batch rebinding analysis were performed: this study revealed that the imprinted polymer has a much greater affinity for the template molecule than the unimprinted one, and a significant selectivity.

Prochiral ketones were sodium borohydride reduced at the chiral interface of amphiphilic dendrimers bearing sugar moieties at their ends. In water, stereoselectivities were improved by using the fourth generation of these amphiphilic dendrimers [G(4)G]. Under heterogeneous conditions (THF) the third generation [G(3)G] gave the best enantioselectivities. Mechanistic studies of such asymmetric induction were performed by molecular modeling, 13 C NMR spectroscopy, Induced Circular Dichroism, as well as reaction parameters: influence of the temperature, cations, molecular structure of the sugar ends and of dendrimer links with the sugars: – in homogeneous conditions (water), the main factor is the ordering and specific orientation of the ketone at the chiral interface; – in heterogeneous conditions (THF) enantioselectivities are due to a chiral intermediate with the C(3) and C(4) sites of the sugar part, and to the C(2) site whose structure is important for ketone positioning.

The aim of this work was to develop new sugar nonionic surfactants from raw materials of plant origin. These nonionic surfactants are based on the noncovalent association between cyclodextrins (CDs) and fatty alcohols or fatty acids. We describe here (i) the preparation of various complexes between β-cyclodextrin (β-CD) and fatty alcohols or fatty acids, (ii) the evaluation of the surfactive properties of the complexes, and (iii) the structure of one of them which presents interesting surfactive properties. Among the prepared complexes, the β-CD/alcohol complexes present high surface tension efficiencies compared with β-CD/acid complexes. The surfactive properties of the β-CD/alcohol complexes are influenced by the length of the hydrocarbon chain and reach an excellent efficiency for guests having 10−12 carbon atoms. For the complex between β-cyclodextrin and undec-10-en-1-ol, the inclusion mode in aqueous solution was described by nuclear magnetic resonance techniques. The results showed a 1:1 stoichiome...

Skin deep: A bioactive formulation for dermal delivery of antihistamines is obtained by using the original properties of catanionic associations towards self-assembly in water. The drug, which participates in its own transport, is preserved from photodegradation when solubilised in the bioactive formulation. The drug release through the skin is also delayed.

A catanionic mixture based on three components, N-dodecyldiethanolamine, decanoic acid and azelaic acid, was prepared and investigated from a physico-chemical point of view and for its antimicrobial activity. The spontaneously formed vesicles were characterized by dynamic light scattering, zeta potential and electron microscopy. These experiments showed spherical vesicles with an average diameter of 200 nm and a zeta potential of +22 mV. The antimicrobial activity of the vesicle dispersion against different strains (Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis, Propionibacterium acnes and Candida albicans), was evaluated and compared with the activity of the components separately. The synergistic effect of these bioactive self-assembled catanionic vesicles on the spectrum of activity and on the cytoplasmic membrane is discussed.

A novel approach to the synthesis of molecularly imprinted polymers via non-covalent linkages has been studied. It relies on the use of thermotropic side group liquid crystal polymer networks. The polysiloxane networks obtained after extraction of the template preserved the mesomorphic organization set up in the presence of the guest molecule. A first batch rebinding analysis was performed: this study revealed that the imprinted polymer has a much greater affinity for the template molecule than has the non-imprinted polymer, and a significant selectivity.

In this work, we present the synthesis of cationic surfactants based on 1-aminoisoindole. The physico-chemical properties were studied by conductometry, tensiometry, dynamic light scattering and transmission electron microscopy in water and in formamide. The reactivity of these novel surfactants has been studied at concentrations below and above critical aggregation concentrations (CAC) and it was found that reactions can proceed in structured media without the addition of other catalysts.

We present a comparative study of the thermotropic and lyotropic phases of 5 surfactants with an aliphatic chain of 12 carbon atoms and a cyclic or acyclic sugar head with different linkages between the two moieties. These linkages can concern different chemical groups or different orientations between the head and the chain. The compounds included the α- and β-N dodecyl-D-maltosides, N-dodecylamino-1-deoxylactitol, N-dodecyl lactobionamide and N-acetyl N-dodecyl lactosylamine. The influence of the polar head (with closed- and opened-type sugars) and the linkage with the hydrocarbon chain on the phases obtained by the heating of the anhydrous compounds and after addition of water was studied by X-ray diffraction and optical microscopy. In the anhydrous state, the surfactants were either crystalline or amorphous. On heating, they went through a liquid crystal smectic phase which, in some cases, was preceded by solid-to-solid transitions. On addition of water, the sequence of phases from the micellar phase to the lamellar phase was accounted for in terms of the geometric model of Sadoc and Charvolin. However, with certain surfactants this sequence was not complete, and the domains of existence of phases were altered.

This review summarizes previous results obtained in synthesis, physicochemical studies and biological applications of fluorinated or semifluorinated compounds. In these series we prepared olefins from which we studied: • the cycloaddition reaction with cyclopentadiene, and the aggregation properties of the obtained substituted norbornenes; • the amidation reaction in formamide microemulsions; • their ability to provide new formulations for blood substitutes or their applications in vitreous surgery. We also prepared new surfactants having polar heads from lactose and glucose derivatives. An interesting phenomenon of gelification in formamide was observed with surfactants synthesized from gluconolactone.

Chemical decontamination of toxic compounds (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidation of mustard gas analogues in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quantitative and chemoselective oxidation of the analogues. In a second formulation, the choice of microemulsion components used allowed us to study the oxidation of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aqueous systems. Formulation de nouvelles microemulsions pour la decontamination par oxydation d'analogues soufres de l'yperite et d'un demi-moutarde adsorbe sur polymere. La decontamination chimique de composes toxiques (pesticides ou toxiques de guerre) est d'une importance croissante. Dans cette etude, nous decrivons l'oxydation de composes soufres modeles de l'yperite en milieu microemulsion. Dans un premier temps, une formulation particulierement bien adaptee a la destruction de stocks d'yperite est decrite: celle ci permet une oxydation rapide, quantitative et chimioselective des modeles du toxique. Une deuxieme formulation nous a ensuite permis de realiser l'oxydation d'un modele tres proche de l'yperite (le demi-moutarde 2-chloroethylphenyl sulfure) formule sur polymere, ouvrant ainsi le champ d'application de nos systemes a la decontamination sur site. Ces resultats demontrent encore une fois l'efficacite et le potentiel des microemulsions pour la destruction de l'yperite en mileu majoritairement aqueux.

Background: Apoptosis is a programmed cell death in multicellular organisms, found in a wide variety of conditions, including inflammatory process, everywhere in the body, including the cornea and conjunctiva. Aim: To evaluate the effect of a new topical formulation of sphingosine-1 phosphate on preventing apoptosis of the corneal epithelium. Setting: Medical University. Materials and Methods: We tested several formulations suitable for topical application. Twenty-five rabbits were distributed among five groups. Group 1 comprised the controls. In Group 2, 20% ethanol was applied topically for 20 seconds; in Group 3, 50 μM topical sphingosine-1 phosphate was applied 2 hours prior to 20% ethanol application. In Group 4, 200 μM topical sphingosine-1 phosphate was applied 2 hours before the 20% ethanol application. In Group 5, only 200 μM topical sphingosine-1 phosphate was applied. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase biotin-dUTP Nick End Labeling (TUNEL) assay. Pairwise comparisons were performed using t-tests with Scheffe's correction. Data were analyzed using STATA 9.0 statistical software. Results: A suspension of sphingosine-1 phosphate in the presence of Montanox 80 was stable and could be formulated without sonication. Epithelial apoptosis was detected only in Groups 2 and 3. Conclusion: Sphingosine-1 phosphate can prevent ethanol-induced apoptosis in the corneal epithelium of rabbits.

We developed a new method of preparation of latex by polymerization of norbornene in aqueous emulsion with SDS, catalyzed by PdCl2. The preparation of small sized latex has been also extended to latex bearing functional groups as alcohol or sugar residues. Two types of catalysts were used: PdCl2 and PdCl2(TPPTS)2. The latex were characterized by light scattering and electron microscopic examination.

The aim of this work was to establish structure-reactivity relationships between chiral aggregates (micelles, vesicles, and "pseudo-micelles" of amphiphilic dendrimers) and asymmetric induction. In water, micelles or vesicles formed with sugar-headed surfactants gave less than 10% ee in the reduction of prochiral ketones by NaBH(4), in contrast with dendrimers bearing the same types of sugar moieties, which gave more than 50% ee under the same reaction conditions. Moreover, in the presence of neoglycodendrimers in THF we have been able to improve reduction of prochiral ketones to give very high stereoselectivity, near 100% in many cases. Comparison of these results suggests that to improve high stereoselectivity it is necessary to work with rigid, well-organized colloidal objects. Copyright 2000 Wiley-Liss, Inc.

New double-chain and gemini catanionic analogues of the glycolipid galβ1ceridentified as a cell receptor of the HIV-1 viruswere easily prepared in two steps from unprotected lactose. Due to their sugar moiety, these new catanionic surfactants were able to be cationized by sodium ions and therefore to be characterized in their monomeric forms by electrospray mass spectrometry. To our knowledge, this is the first time that catanionic surfactants have been directly observed, proving undoubtedly their existence as monomeric species. These new catanionic glycolipids showed interesting anti-HIV-1 activities, acting as monomeric analogues of galβ1cer. Finally, these new catanionic glycolipids were characterized by their surface active properties, by lamellar mesophases, and by their aptitude to spontaneously form vesicles.

We described in this work new glucose-persubstituted poly(amidoamine) dendrimers. The physicochemical properties of these new amphiphilic dendrimers were investigated in water, showing that these new amphiphilic dendrimers were able to solubilizate increasing quantities of hydrophobic compounds (pyrene or aromatic ketones) in water, depending on the number of microcavities in each dendrimer. These dendrimers were observed to behave like unimolecular micelles. For the first time the formation of aggregates of these carbohydrate dendrimers in superstructures could be observed by electron microscopy and light scattering. Moreover, it is the first example of asymmetric induction in the “pseudomicellar” solution of a chiral amphiphilic dendrimer: therefore, asymmetric reduction of the prochiral aromatic ketone (benzoylcyclohexane) was achieved by NaBH4 with a chemical yield of 95% and an enantiomeric excess of 50%.

Sodium borohydride reduced, at the chiral interface of an amphiphilic dendrimer, prochiral ketones to the corresponding chiral alcohols in high yields (>90%) with enantioselectivities over 95% in THF (ex: ee of 99.4% was obtained in reduction of acetophenone).

Background. The 2009 novel influenza A/H1N1 virus pandemic did not spare solid organ transplant (SOT) recipients. We aimed to describe the behavior of pandemic influenza infection in a group of SOT recipients in Argentina. Methods. Data from 10 transplant (Tx) centers were retrospectively collected for SOT that presented with a respiratory illness compatible with pandemic influenza A infection, between May and September 2009. Cases were defined as suspected, probable, or confirmed according to diagnostic method. Results. Seventy-seven cases were included. No significant differences in presenting symptoms, pulmonary infiltrates, and graft involvement were found among 35 suspected, 19 probable, and 23 confirmed cases. The 33 ambulatory cases had significantly more sore throat and headache when compared with 34 cases admitted to medical ward (MW) and 10 admitted to intensive care unit (ICU), 9 of whom required ventilatory support. MW and ICU cases had significantly more dyspnea, hypoxemia, pulmonary infiltrates, and graft dysfunction. Time from onset of symptoms to first visit and to treatment was significantly longer in MW and ICU cases (P=0.008). Coinfections were found in six cases. Most cases received oseltamivir for 5 to 10 days. Six patients (7.8%) died from viral infection at a median of 15 days from admission. No differences in outcome were seen related to the transplanted organ, the immunosuppressive regimen, time from Tx, or confirmation of diagnosis. Conclusions. Mortality is higher in Tx recipients than in the general population. Poor outcome seems to be related to a delay in the beginning of treatment.

Complexes of DNA with various cationic vectors have been largely used for nonviral transfection, and yet the photochemical stability of DNA in such complexes has never been considered. We studied, for the first time, the influence of DNA complexation by a cationic lipid and polymers on the amount of damage induced by benzophenone photosensitization. The localization of benzophenone inside the hydrophobic domains formed by a cationic lipid, DOTAP (N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride), and close to DNA, locally increases the photoinduced cleavage by the reactive oxygen species generated. The same effect was found in the case of DNA complexation with an amphiphilic polymer (polynorbornenemethyleneammonium chloride). However, a decrease in DNA damage was observed in the case of complexation with a hydrophilic polymer (polyethylenimine). The DNA protection in this case was because of the absence of benzophenone hydrophobic incorporation into the complex, and to DNA compaction which decreased the probability of radical attack. These results underline the importance of the chemical structure of the nonviral transfection vector in limiting the risks of photo-oxidative damage of the complexed DNA.

Like other amphiphilic compounds, bolaforms do not always possess surfactant properties; it depends on the spacer chain length and the nature of the polar head group (both sufficiently hydrophobic or hydrophilic, respectively, to intensify the amphiphilic properties). In this regard, unsymmetrical bolaamphiphiles bearing a sugar polar head group and a carboxylic acid function at the opposite ends of a hydrophobic binding spacer were synthesized. These biocompatible sugar-derived bolaforms were associated with basic fatty amines, by an acid–base reaction, to obtain catanionic mixtures. Associations with 1,7-lactobionamidoheptanoic acid and decylamine or octylamine spontaneously form stable 200–600 nm vesicles. This new type of association may find an application in drug delivery since catanionic vesicles can transport active substances inside the hydrophilic core, as well as hydrophobic drugs within the bilayer.

A new family of antioxidant ion-pair surfactants was developed by acid-base association of a fatty amine (C12 or C16) with caffeic acid, a natural antioxidant molecule. The amphiphilic molecules obtained, spontaneously formed stable vesicles in water with hydrodynamic diameters around 230 nm. Moreover, as shown by a surface tension study, they presented a phase transition from micelles to vesicles. The maintenance of the antioxidant properties of both caffeate ion-pair surfactants was confirmed by the DPPH test. The amphiphilic properties associated with the antioxidant ability of these new caffeates were used to protect complexed DNA by cationic surfactant (CTAB) from photooxidative cleavage induced by benzophenone photosensitization.

Interactions between vesicles made of a sugar-derived tricatenar catanionic surfactant (TriCat), used as drug delivery vectors, and giant unilamellar vesicles (GUVs) encapsulating magnetic nanoparticles are investigated in order to understand the drug internalisation process. It appears that the addition of the catanionic vesicles to the GUV induces important shape modifications and membrane instabilities that cannot be explained by the insertion of monomeric TriCat into the membrane. This indicates a specific interaction between the TriCat vesicles and the lipidic membrane.

We describe a modular synthesis for single-chain and “semi-gemini” glycolipids. We found that slight alterations in the structures of these amphiphiles led to marked differences in the morphology of their aggregates in solution. We also demonstrate, for the first time, the formation of stable gels in the structured nonaqueous solvent formamide.

Synthetic glycolipids are of interest for their biological applications requiring interactions with membrane proteins. Depending on their structures, new series of glycolipids have applications in extraction of membrane proteins or medical applications as mimics of natural ligands of proteins.

We investigated here the micellization in water of three surfactants: (N-dodecylamino)lactitol, (N-dodecyl)lactobionamide, and (N-acetyl N-dodecyl)lactosylamine, having n-alkyl chain lengths of 12 carbon atoms and different lactose-based polar heads. The micellization is studied by small-angle neutron and X-ray scattering. The characteristic dimensions of the micelles are derived from the I(q) curve fittings. We demonstrated the existence of spherical or oblate ellipsoidal micellar structures. The differences were attributed to differences in steric hindrance of the polar head enabling or preventing formation of spherical micelles. We pointed out the particular role of steric hindrance at the junction between the hydrophobic chain and the polar head. The formation of oblate ellipsoidal micelles attests to a relatively low steric hindrance at this junction ((N-dodecylamino)lactitol and (N-dodecyl)lactobionamide) whereas the formation of spherical micelle displays an important steric hindrance as observed for (N-acetyl N-dodecyl)lactosylamine which includes a bulky linkage. The surface areas per polar head in the micelles are confronted to the minimum areas per molecules deduced from surface pressure measurements. The results are in good agreement excepted in the case of (N-dodecyl)lactobionamide. The experimental results obtained with micellar solutions of N-dodecyllactobionamide from both neutron scattering and surface pressure measurements exhibit a particular comportment of this surfactant compared with two other surfactants studied in regard to the intermicellar interactions and the minimum area per molecule at the air/aqueous solution interface. We suggest that this particular behavior could be the consequence of a very important solvation of the (N-dodecyl)lactobionamide polar heads due to the presence of an amide group in this molecule. This important solvation could modify the interactions between the micelles and the apparent size ofisolated molecules at the air/aqueous solution interface. Over parallel explanations may be suggested as formation of dimers or trimers below the critical micelle concentration (cmc) and above the cmc the existence of relatively strong intermicellar interactions stemming from the distribution of dipoles over the surface in these micelles due to the presence of the amide group.

New routes in three or four steps to synthetic bolaamphiphilic analogs of galactosylceramide (GalCer) are presented in this work, using unprotected lactose as the starting sugar. Some of these new anionic compounds obtained in good yields bind to the V3 domain of HIV-1 gp 120 and thus are the base of potential low-cost anti HIV-1 drugs. Moreover, structure-activity relationships show that the hydrophobic moiety of the molecule plays a key role in this activity. Synthese de bolaamphiphiles analogues du galactosylceramide (GalCer) pouvant interagir avec la boucle V3 de la gp 120 du VIH-1: role cle′ de leur hydrophobie. De nouveaux compose′s bolaformes analogues du galactosylce′ramide (GalCer) sont pre′sente′s dans ce travail. Leur synthese en trois ou quatre e′tapes met en jeu le lactose non-prote′ge′ comme sucre de de′part. Certains de ces nouveaux compose′s se lient a la boucle V3 de la gp 120 du VIH-1 et constituent donc une base pour obtenir de nouveaux agents anti VIH a faible cout. En outre, les relations structure-activite′ montrent que la partie hydrophobe de la mole′cule joue un role cle′ dans cette activite′.

The natural packaging of DNA in the cell by histones provides a particular environment affecting its sensitivity to oxidative damage. In this work, we used the complexation of DNA by cationic surfactants to modulate the conformation, the dynamics, and the environment of the double helix. Photo-oxidative damage initiated by benzophenone as the photosensitizer on a plasmid DNA complexed by dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), cetyltrimethyammonium chloride (CTAC) and bromide (CTAB) was detected by agarose gel electrophoresis. By fluorescent titration in the presence of ethidium bromide (EB) and agarose gel electrophoresis, we experimentally confirmed the complexation diagrams with a critical aggregation concentration on DNA matrix (CAC DNA) delimiting two regions of complexation, according to the DNA-phosphate concentration. The study of the photo-oxidative damage shows, for the first time, a direct correlation between the DNA complexation by these surfactants and the efficiency of DNA cleavage, with a maximum corresponding to the CAC DNA for DTAC and CTAC, and to DNA neutralization for CTAC and CTAB. The localization of a photosensitizer having low water solubility, such as benzophenone, inside the hydrophobic domains formed by the surfactant aggregated on DNA, locally increases the photoinduced cleavage by the free radical oxygen species generated. The inefficiency of a water-soluble quencher of hydroxyl radicals, such as mannitol, confirmed this phenomenon. The detection of photo-oxidative damage constitutes a new tool for investigating DNA complexation by cationic surfactants. Moreover, highlighting the drastically increased sensitivity of a complexed DNA to photo-oxidative damage is of crucial importance for the biological use of surfactants as nonviral gene delivery systems.

Liquid‐crystal elastomers, imprinted around indole, are assessed as artificial enzymes for the isomerisation of benzisoxazole into 2‐cyano phenol. Two types of material are synthesised, tested in the catalysis and compared with non‐liquid‐crystal imprinted polymers: an imprinted liquid‐crystalline elastomer and a semi‐interpenetrated imprinted liquid‐crystal network. The catalytic effect of all materials is close. However, the main benefit for the liquid‐crystal elastomer is shown to be the shape memory of the material at the molecular scale, because the isomerisation kinetics are found to be identical before and after deformation of the cavities either by thermal treatment up to the isotropic state or by solvent induced swelling. This fact is related to the coupling between the order and the conformation of the polymer chains, which is fixed by the crosslinking process. On the other hand, the imprinted sites of the semi‐interpenetrated imprinted liquid‐crystal elastomer are shown to be almost 100 times m...

Non-ionic surfactants based on sugars are of interest to both chemists and biochemists. They have potential pharmaceutical (biocompatible formulation) biochemical (extraction of membrane proteins) and medicinal applications; generally these derivatives are not readily synthesized as the starting sugars require protection. We present here routes, avoiding protection of the starting sugars, to new series of surfactants derived from lactose, glucose, gluconic or lactobionic acids. By changing the tail or the hydrophobic body bonded to the sugar heads, we have synthesized sugar-based amphiphilic compounds having (1) one chain, (2) one fluorinated chain, (3) a double chain or (4) two sugar heads (bolaamphiphilic compounds) All these compounds form aggregates in solution: direct, reverse micelles, or vesicles. Fluorinated molecules give gels in aqueous or non-aqueous media. Some of them are interesting products to extract membrane proteins or to formulate solution of hydrophobic acids to realize enzymatic reactions. Finally soluble analogs of Galcer possess activity against both HIV andAspergillus fumigatus, a yeast responsible for opportunistic infections in AIDS patients.

Molecules of amphiphiles associate in structured solvents to form flexible interfacial films, which may then join up to form crystals. A considerable variety of structures are observed in such crystals. In most cases, consideration of the geometry of the structures, based on frustration analysis, can account for the sequence of phases observed in these systems, independent of the chemical nature of the amphiphilic molecules. The geometric theory is well validated with structured polar solvents whose properties may be either quite similar or quite distinct from those of water. In surfactant-non-aqueous polar solvent systems, only the theoretical phases are in fact observed. However, in water, intermediate phases not accounted for by the geometric theory may be observed. Their conditions of formation are not well understood, indicating that complex phenomena take place in water, a solvent which is nevertheless regarded as an ideal and model solvent.

We report here a small angle neutron scattering (SANS) study of the micellization of SDS in formamide. We show that a compound with a hydrophobic chain containing 12 carbon atoms forms micelles in formamide. The mechanism of self-association is in agreement with a multiple equilibrium model rather than a pseudophase model, as the aggregates were shown to increase in size over a large concentration domain. This was attributed to smaller solvophobic effects and lower interfacial energy in formamide than in water.

We describe the synthesis and the physicochemical study of new ion-pair amphiphiles from a mixture of bicyclic, cyclic, linear or branched amines and fatty acids of three chain lengths. Surface-tension measurements of bicyclic, cyclic and branched structures of ammonium/alkanoate acid ion pairs show a phase transition, with two plateaux in the plot of surface tension versus log(c) (c=concentration). Such behaviour is related to the structure of the counterion, the alkyl chain length and the temperature. Pulsed gradient spin echo NMR spectroscopy experiments were performed to demonstrate the existence of micelles on the first plateau and to confirm the phase transition. The existence of vesicles on the second plateau of the surface tension was proved by CryoTEM observation and dynamic light scattering (DLS) measurements. Mainly, according to the structure of the counterion, there is either a strong association and a positioning along the chain leading to vesicles or a less strong association leading to external positioning and the formation of micelles at low concentrations or vesicles at higher concentrations.

In a first part, the comprehension of the antiviral efficiency of a Gemini catanionic analogue of GalCer Gem16-12-16 is deepened by studying its interactions with phospholipids. Monolayers at the air/water interface are used as 2D models of biological membrane. Adsorption kinetics measurements are performed at Gemini concentrations below the critical aggregation concentration (CAC) and show an incorporation of Gem16-12-16 molecules into the fluid phase as well as into the condensed domains of a DPPC monolayer. Compressing such a mixed monolayer leads first to the squeezing out of Gem16-12-16 molecules from the fluid part of the monolayer and above 30 mN/m to the squeezing out from the condensed part. SAXS/WAXS studies are performed using mixtures of Gem16-12-16 catanionic surfactant and DPPC. Bilayers have been observed at high concentrations for Gem16-12-16 in water, in a large temperature range. Mixing with DPPC produces mixed bilayers above the corresponding chain melting temperature. At room temperature, partially lamellar aggregates with local nematic order are observed. In a second part, the ability to encapsulate anti-HIV drugs of another analogue of GalCer Tri16-12-12 is studied. A difference in monolayer stability of pure Tri16-12-12 is observed on water or on buffer subphases, encouraging us to perform the first encapsulation assays in buffer solutions. First results on a fluorescent probe entrapment inside the vesicles are performed in order to validate the use of these vectors in anti-HIV therapy.

A new family of polymerizable surfactants was synthesized starting from a 1:1 mixture of alkylcarboxylic acids (C10 to C16) and norbornene methyleneamine. The ion-paired surfactants exhibited cloud temperatures, surface activity, and critical aggregation concentrations that differed according to the chain length, with a variation indicating a strongly associated ion pair. Light-scattering measurements and electron microscopy observations confirmed the spontaneous formation of stable vesicles (90 nm < d < 370 nm). Also, NMR experiments showed the enclosing of the norbornene part inside the vesicle membrane. Moreover, the addition of sodium chloride allowed the formation of a tubular structure leading to a viscous or gel-like solution. Finally, a preliminary vinylic polymerization test proved the polymerizable character of these ion-paired surfactants by an organometallic catalysis, leading to partially polymerized vesicles.