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The fabrication of multifunctional nanostructures constitutes an interesting area of research. Here we used a simple fullerene–amine coupling chemistry to produce a photofunctional and antioxidant magnetic material composed of multiple C60 molecules covalently bound to core monodispersed superparamagnetic iron oxide nanoparticles (SPIONs). For this, core SPIONs were synthesized by thermal decomposition, using iron(III) acetylacetonate as the iron precursor, and the resulting hydrophobic SPIONs were coated with a thin amino-functionalized silica layer. C60 molecules were covalently linked to the core SPIONs by a simple fullerene–amine coupling reaction, a method promoting the assembly of the pursued nanocomposite. Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy were used all along the fabrication process to demonstrate the efficient assembly of the SPION/C60 nanocomposite. We confirm that the latter brings together the disparate physico-chemical properties of its components. Using vibrating sample magnetometry we demonstrate that the core SPION confers a superparamagnetic character to the nanocomposite. We also demonstrate that fullerenes confer photosensitizing properties to the latter, as illustrated by the photo-oxidation of 1,5-dihydroxynaphthalene. Interestingly, the hydrophobic SPION/C60 nanocomposite was easily solubilized in water using polyvinylpyrrolidone, offering the possibility of evaluating its properties in physiological conditions and paving the way to further biomedical applications. Therefore, we also demonstrate that water-soluble SPION/C60 has a good T2 relaxivity, conferred by its core superparamagnetic component, and could potentially be used as a contrast agent in magnetic resonance imaging. Furthermore, we show that the hydrophilic nanocomposite has a remarkable antioxidant capacity which is provided by its fullerene component. In summary, our work provides a facile method to produce composite nanostructures that bring together the attractive properties of monodispersed SPIONs and those of fullerene C60 molecules, which can be exploited in a broad range of applications, such as photodynamic therapy, photocatalytic oxidation of organic pollutants and radical scavenging, to name only a few.

This work deals with the covalent coupling of azide-functionalized polymeric nanoparticles as a reactive core and amino-terminated PAMAM dendrons as a reactive shell. The nanoassemblies thereby obtained could be modified after the dendronization step by grafting an alkynyl Bodipy dye on the unreacted azide moieties. Only a few steps are required to attain nanoassemblies that could mimic dendrimers of high generation with sizes of nano-objects beyond those of dendrimers. The structure of the nanoassemblies are composed of a polystyrene core, an inner shell including the Bodipy dyes along with the internal branches of the PAMAM, and the terminal amino groups from the outer shell. The dendritic shell acts as a protective layer that prevents NP from aggregation in a surfactant free aqueous solution. The nano-objects display absorption and emission maxima above 500 nm with brightness that are the same order of magnitude than Qdots. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 115–126

In this study, the synthesis of water-soluble fullerene derivatives bearing on one side a poly(amidoamine) (PAMAM) dendron with peripheral carboxylic groups and an alkyne moiety on the other side is presented. Fullerodendrimers with tert-butyl ester groups at the periphery were first prepared by treating C60 with unsymmetrical malonates through the use of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)/I2 or DBU/CBr4 conditions. The latter led to an unexpected addition of dibromocarbene on C60. The tert-butyl esters were then cleaved using formic acid and gave the corresponding carboxyfullerene derivatives. The second generation with eight carboxylic groups at the periphery was easily dissolved in water, whereas the first generation with its four carboxylic groups can only be solubilized in a basic medium. These compounds self-assemble into micelle-like aggregates probably composed of a cluster of C60 surrounded by a PAMAM shell. The alkyne moiety was then used as a chemical anchor to immobilize in water fullerodendrimers on the surface of azido-coated polymer nanoparticles by means of the copper(I)-catalyzed azide and alkyne cycloaddition reaction. At room temperature, this reaction is competing with azido cycloaddition onto the fullerene core. Given the high density of azide anchoring groups on the nanoparticle surface and the size of the fullerodendrimers, unreacted azides are still active and are available for subsequent functional arrangements. This strategy paves the way for the design of functional fullerene-rich nanomaterials that could be of interest in the field of materials science.

The technological application of sensitized upconversion based on triplet-triplet annihilation (TTA) requires the transition from systems operating in liquid solutions to solid-state materials. Here, we demonstrate that the high upconversion efficiency reported in hyper-cross-linked nanoparticles does not originate from residual mobility of the embedded dyes as it happens in soft hosts. The hyper-reticulation from one side blocks the dyes in fixed positions, but on the other one, it suppresses the nonradiative spontaneous decay of the triplet excitons, reducing intramolecular relaxations. TTA is thus enabled by an unprecedented extension of the triplet lifetime, which grants long excitons diffusion lengths by hopping among the dye framework and gives rise to high upconversion yield without any molecular displacement. This finding paves the way for the design of a new class of upconverting materials, which in principle can operate at excitation intensities even lower than those requested in liquid or in rubber hosts.

The convergent synthesis of fluorescent polystyrene core–PAMAM shell nanoparticles in the 15–20 nm diameter range is presented using azido-coated nanoparticles (NPN3) as a clickable platform. The c...

Stable translucent aqueous suspensions of azide-functionalized cross-linked nanoparticles (NPs), with diameters in the 15–20 nm range, were prepared using two synthetic approaches. Copolymerization of azidomethylstyrene (VBN3), styrene, and divinylbenzene in various oil-in-water microemulsions led to NPs with modulable azide contents (0.53–0.78 mmol/g) and surface over volume distributions. Surface modifications of reactive NPs bearing chlorobenzyl groups, produced by microemulsion copolymerization of vinylbenzylchloride, with sodium azide led to azido-coated NPs with high densities of peripheral groups (0.13–0.45 mmol/g). It is shown that the nature of the surfactant used for the preparation of the microemulsion has an impact on the incorporation of VBN3 in the polymer particles as well as on the surface reaction yield. The azide-functionalized NPs were used as clickable polymeric scaffolds for the grafting of sparingly water-soluble dansyl and fluorescein derivatives through copper(I)-catalyzed azide-alkyne cycloaddition in water in the presence of surfactants as solubilizing agents to produce fluorescent NPs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Sensitized triplet–triplet annihilation in multicomponent organic systems is already demonstrated to be suitable for obtaining effi cient up-conversion in solution with excitation power densities comparable to solar irradiance, but loses effi ciency in the solid state. Here, it is demonstrated that it is possible to reduce this limitation by incorporating a standard bicomponent system in polymer nanoparticles. The confi nement of all of the involved photophysical processes in a nanometer-scale volume makes each nanoparticle a single and isolated high-effi ciency up-converting unit. As a consequence, these dualdye-loaded nanoparticles can be used to produce drop-cast fi lms, as well as dopants for polymeric matrices, preserving the performances of the starting moieties in solution.

Core-shell type dual fluorescent nanoparticles (NPs) in the 16 nm diameter range with a selective ligand (cyclam) attached to the surface and two fluorophores--9,10-diphenyl-anthracene (donor, D) and pyrromethene PM 567 (acceptor, A)--embedded within the polymer core were synthesized and their fluorescent and copper-sensing properties were studied and compared to single D-doped and A-doped NPs. The acceptor (A) and donor (D) dyes were chosen to allow two sequential Förster resonance energy transfer (FRET) processes from D to A and from the encapsulated dyes to copper complexes that form at the surface and act as quenchers. NPs with different D/A loads were readily obtained by two consecutive entrapments of the dyes. Dual NPs present tunable fluorescence emission that is dependent on the doping ratio. FRET from D to A results in sensitized emission from A upon excitation of D, with FRET efficiencies reaching 80 % at high acceptor loads. A 9-fold amplification of the signal of A is observed at high D-to-A ratios. Single- and dual-dye-doped NPs were used to detect the presence of cupric ions in water by using the quenching of fluorescence as a transduction signal. In accordance with the spectral overlaps and the values of the critical distance (R0) of D- and A-copper complex pairs, the acceptor is much more sensitive than the donor. In dual fluorescent NPs, the sensitized emission of A is efficiently attenuated whereas the remaining emission of D is much less affected, allowing the detection of copper in a ratiometric manner upon excitation at a single (D) wavelength. Dual-dye-doped NPs with the highest acceptor loads (23 A-per-NP) were found to be the most sensitive for the detection of copper over a wide range of concentrations (20 nM to 8.5 microM). Owing to its great convenience and modularity, the cascade FRET strategy based on dual fluorescent NPs holds great promise for the design of various sensing nanodevices.

The synthesis and pH-sensing properties of fluorescent polymer nanoparticles (NPs) in the 20 nm diameter range with a sensitive dye covalently attached to the particle surface and a reference dye entrapped within the particle core are presented. Fluorescein-functionalized NPs were readily obtained by conjugation of fluorescein isothiocyanate (FITC) to amine-coated crosslinked polystyrene-based nanoparticles prepared by microemulsion polymerization followed by postfunctionalization. This all water-based method gave access to stable aqueous suspensions of pH-sensing fluorescent NPs. The encapsulation of the insensitive reference fluorescent dye (1,9-diphenylanthracene, DPA) was then conveniently achieved by soaking leading to dual fluorescent NPs containing about 20 DPA and 55 fluorescein, as deduced from spectroscopic analyses. This core-shell type architecture maximizes the interactions of the sensing dye with the medium while protecting the reference dye. The variations of the ratio of the fluorescence emission intensities of the sensitive dye (fluorescein) to the reference dye (DPA) with pH show that the dual fluorescent NPs act as a ratiometric pH sensor with a measuring range between pH 4 and pH 8. This pH nanosensor was found to be fast, fully reversible, and robust without any leaching of dye over a long period of time. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6206–6213, 2008

A series of stable and translucent colored nanolatex, that is, colloidal aqueous suspensions of dye-tagged polymer nanoparticles (NPs) in the 15- to 20-nm diameter range, have been prepared by covalent attachment of azobenzene chromophores to the surface of reactive NPs. Primary crosslinked NPs bearing chlorobenzyl groups were produced by microemulsion copolymerization of styrene and vinylbenzylchloride. Amine-functionalized NPs were obtained after a second functionalization step with polyamines (cyclam and polypropyleneimine dendrimers of first and third generations). Dye-doped particles were obtained by reacting pyridylazo-dimethylaminobenzene (PADA) with chlorobenzyl-NPs and by reacting amine-reactive dimethylaminoazobenzene dyes (DABsyl, DAB-ITC) as well as Disperse Red 1 acrylate with polyamine-coated NPs. Regardless the dye solubility, the grafting readily proceeded in aqueous suspensions at room temperature in the presence of a cationic surfactant without added solvent. Purple, red, and orange suspensions (maximum absorption around 550, 500, 430 nm), with dye loads ranging from 0.3 to 1.2 mmol/g, corresponding to 400–1800 azobenzene residues per NP, are obtained. The reported results indicate that functional polymer NPs, with remarkably accessible multiple anchoring sites, are useful building blocks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3375–3386, 2008

The synthesis and properties of well-defined core–shell type fluorescent metal-chelating polymer nanoparticles NP, in the 15 nm diameter range, with a fluorophore (9,10-diphenylanthracene: DPA) entrapped in the particle core and a selective ligand (1,4,8,11-tetraazacyclotetradecane: Cyclam), grafted onto the surface are presented. NPs with different number of dye-per-particle are readily obtained by entrapment of the fluorophore within the polymer core. The ligand-coated NPs exhibit a high affinity for Cu2+ ions in aqueous solution and quenching of the DPA fluorescence is observed upon binding of copper. The quenching of fluorescence arises through energy transfer (FRET) from the dye to the copper-cyclam complexes that form at the NP surface with an operating distance (d) in the 2 nm range. A simple core–shell model accounts for the steady-state and time-resolved fluorescence titration experiments: dye molecules located in the outer sphere (thickness d) of the NPs are quenched while the fluorescence of dyes embedded more deeply is not affected by the binding of copper ions. The observed high quenching efficiency (60–65 %), which is tightly correlated to the volumic and microstructural features of the NPs, shed light on the enhanced accessibility inherent in nano-sized templates. The response towards different metal ions was investigated and this confirmed the selectivity of the nanoparticle template-assembled sensor for cupric ions.

Azamacrocycles bearing four arylsulfonyl or arylsulfinyl pendant arms have been synthesised with good yields through nucleophilic addition of 1,4,8,11-tetraazacyclotetradecane (cyclam) to phenylvinylsulfone, phenylvinylsulfoxide or (R)-tolylvinylsulfoxide in isopropanol/water media. The crystal structure of the tetraethylsulfonylphenyl substituted macrocycle has been determined by X-ray crystallography. Preliminary studies of the coordination properties of these functionalised macrocyles towards Cu(II) and Eu(III) indicate that pendant sulfoxide groups act as oxygen donor coordinating groups.

Conjugate additions of cyclam to perfluorohexyl vinyl sulfone and sulfoxide, which act as efficient fluorous Michael acceptors, readily give access to new fluoro-ponytail tetraazamacrocycles in good yields. The solubility of the N-tetrasubstituted macrocycles depends dramatically on the nature of the polar function (SO or SO2): the sulfoxide cyclam derivative is soluble in perfluorodecaline (pfd) and perfluoromethylcyclohexane (pfmc) while the sulfonyl derivative is almost insoluble in organic or fluorous solvents. In agreement with the well known affinity of cyclam for copper(II) ions, stable copper complexes of the fluorous macrocyclic ligands have been isolated and characterized. In chloroform/methanol, complexes with four perfluorinated tails have been obtained from reaction of the tetra-N-perfluorohexylsulfinyl-substituted macrocycle with copper nitrate and copper perfluorocarboxylate. In trifluoroethanol, a selective retro-Michael reaction has been observed and the same reaction specifically gives copper complexes of the tri-N-substituted macrocycle. Complexes with three and four fluorous tails associated with perfluorocarboxylate counteranions are soluble in fluorous solvents (pfd and pfmc). These copper complexes were tested as catalysts for the oxidation of cyclohexene by molecular oxygen in the presence of tert-butyl hydroperoxide (tbhp). The oxidation reactions proceed under fluorous biphasic conditions and the catalyst can be recovered and reused. Quenching experiments indicate that cyclohexenyl hydroperoxide is the main oxidation product of the reaction performed with or without tbhp. Interestingly, these perfluorinated copper complexes are good, recyclable catalysts for the oxidation of cyclohexene by molecular oxygen without tbhp at room temperature and 65 °C.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Metal-complexing nanoparticles, with average diameters ranging from 15 to 25 nm, are prepared using a two-step procedure: synthesis of reactive nanoparticles followed by post-functionalisation with a selective macrocyclic ligand, cyclam (tetraazacyclotetradecane). The starting nanoparticles, containing benzylhalide reactive groups are readily prepared by copolymerisation of vinylbenzylchloride in ternary oil-in-water microemulsions stabilized by a cationic surfactant (dodecyltrimethyl ammonium bromide). Elemental analyses of the polymer reveals that exchange of chlorine for bromine as well as hydrolysis of chloromethyl residues occur within the reaction medium, the rate of both side reactions being dependent upon the experimental conditions. The overall content of reactive chloro- and bromobenzyl moieties range from 0.7 to 1.1 mmol g–1. Reaction of cyclam, performed directly in the aqueous suspensions, gives rise to stable suspensions of functionalised nanoparticles containing 0.2 to 0.3 mmol ligand g–1. Spectrophotometric measurements show that these cyclam post-functionalized nanoparticles exhibit a ‘solution-like’ complexation behaviour thus demonstrating remarkable ligand accessibility. To cite this article: C. Larpent et al., C. R. Chimie 6 (2003).

N,N′-disubstitution of cyclam without the use of protecting groups was investigated. This macrocycle reacted with two equivalents of a Michael acceptor in chloroform to yield as a major isolated compound the 1,8 di-N,N′-substituted macrocycle. Running the same reaction in the presence of one equivalent of para-toluenesulfonic acid led to the 1,11-di-N,N′-substituted macrocycle as the major product. Each regioisomer has been isolated and fully characterized. The observed regioselectivity is discussed with respect to the reactivity of the unprotonated or protonated monoalkylated intermediate. A site of protonation for the latter intermediate is deduced from an NMR study. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Recycling chemistry of metals and oxides relies on three steps: dissolution, separation and material reformation. We review in this work the colloidal approach of the transfer of ions between two complex fluids, i.e. the mechanism at the basis of the liquid-liquid extraction technology. This approach allows for rationalizing in a unified model transformation such as accidently splitting from two to three phases, or uncontrolled viscosity variations, as linked to the transformation in the phase diagram due to ion transfer. Moreover, differences in free energies associated to ion transfer between phases that are the origin of the selectivity need to be considered at the meso-scale beyond parameterization of an arbitrary number of competing “complexes”. Entropy and electrostatics are taken into account in relation to solvent formulation. By analogy with electronics dealing about electrons transported in conductors and semi-conductors, this “ienaic” approach deals with ions transported between nanostructures present in colloidal fluids under the influence of chemical potential gradients between nanostructures coexisting in colloidal fluids. We show in this review how this colloidal approach generalizes the multiple chemical equilibrium models used in supra-molecular chemistry. Statistical thermodynamics applied to self-assembled fluids requires only a few measurable parameters to predict liquid-liquid extraction isotherms and selectivity in multi-phase chemical systems containing at least one concentrated emulsified water in oil (w/o) or oil in water (o/w) microemulsion.

Stable translucent aqueous suspensions of ligand-functionalized nanoparticles, with average diameters ranging from 12 to 20 nm and containing from 0.25 to up to 0.75 mmol of ligand/g, are readily obtained by copolymerization in oil-in-water microemulsions of a polymerizable tetraaza macrocycle, vinylbenzylcyclam (cyclam: 1,4,8,11-tetraazacyclotetradecane). These nanoparticles exhibit a very high selectivity for cupric ions with binding capacities of up to 0.65 mmol of Cu/g as well as a remarkable ligand accessibility, deduced from spectrophotometric titration, with about 75% of the cyclam residues located near the surface for nanoparticles in the 12-13 nm range. Core-shell bimetallic nanoparticles are obtained by cation exchange. The cyclam-functionalized nanoparticles are comparable to high-generation PAMAM dendrimers in their ability to complex metals.

The synthesis and surfactant behaviour of two series of sulfosuccinic diesters, AOT-related compounds, are described [Aerosol-OT 1: sodium bis(2-ethylhexyl) sulfosuccinate]. The first family contains unsaturated, racemic or enantiopure, 2-ethylhex(en)yl chains with various positions of the double bond. These compounds are readily prepared from the corresponding unsaturated alcohol by the standard two-step procedure; their critical micelle concentrations are higher than those of normal AOT and depend on the position of the double bond. The second series consists of nonsymmetric homologues with two different substituents: various unsymmetrical sulfosuccinic diesters with two enantiopure saturated or unsaturated chains of opposite configuration, or with two different substituents like methyl and 2-ethylhexyl, hydrogenated and deuterated chains as well as saturated and unsaturated chains are described. These unsymmetrical sulfosuccinic diesters are readily obtained in a three-step synthetic procedure involving the regiospecific sulfonation of maleic monoester in aqueous medium. The structure of the sodium 4-alkyl-2-sulfosuccinic acid key intermediate is unambiguously resolved by NMR comparative analysis of the hydrogenated and deuterated derivatives. The surfactant behaviour of some unsymmetrical compounds is studied.

Both the (R) and (S) enantiomers of 2-ethylhex-5-en-1-ol (R)-(−)-1, (S)-(+)-1 and 2-ethylhexan-1-ol (R)-(−)-2, (S)-(+)-2 were prepared in good yields and in high enantiomeric excess via lipase-catalyzed transacetylation of racemic alcohols 1 and 2 with vinyl acetate. Various experimental conditions (lipase PSL or PLF, solvent and temperature ranging from 30 to −30 °C) are used and their influence on the enantioselectivity and on the reaction rate is evaluated. The (S) unsaturated alcohol 1 is specifically esterified by lipase PS in CH2Cl2 at 0 °C with a very high enantiomeric ratio (E ≈ 750) thus allowing the production of both enantiomers (R)-(−)-1 and (S)-(+)-1 with fairly good yields from the same enzymatic transformation. The comparison of unsaturated and saturated primary alcohols 1 and 2 shows that, for a similar atomic framework, the enantioselectivity of PSL is greatly enhanced by the presence of a terminal double bond. On the other hand, an enhancement of PSL enantioselectivity without loss of catalytic activity is achieved by decreasing the temperature to −30 °C thus giving access to both enantiomers.

N-Monoalkylated azamacrocycles are selectively obtained by reacting cyclam (1,4,8,11-tetraazacyclotetradecane) with equimolar amounts of Michael acceptors in chloroform in the presence of one equivalent of acid (TsOH). This chemoselective addition provides a general route to new mono-substituted azamacrocycles with various pendant groups such as sulfonic acid, ester, amide, nitrile, sugar or crown ether. The selectivity for monoaddition results from protonation of the azamacrocycles in the presence of one equivalent of acid.

Time-resolved laser-induced fluorescence (TRLIF) has been used for interaction studies between europium(III) used as a fluorescent probe and a new micellar system (TAC8) of a “diblock” surfactant–cage molecule containing a cage (cyclam) as a complexation part linked to a sugar-based surfactant part. The effect of each constituent (cage and surfactant unit) as well the complete molecule on the europium fluorescence have been studied. By using the hypersensitive transition of europium, it was shown that the separate constituents, e.g. cyclam and surfactant, had little effect. On the other hand, the complexation constant between europium and TAC8 was close to 102 demonstrating that a synergetic effect is achieved with such a diblock surfactant–cage molecule.

Bis-tetraazacyclotetradecanes (bis-cyclam) are readily prepared with fairly good yields in a one step procedure from non-protected cyclam. The synthesis involves a selective addition of cyclam on bis-acrylamides in chloroform in the presence of one equivalent of p-toluenesulfonic acid.

New reactive-surfactants, N-alkylglucosylacrylamides and N-alkylglucosylmethacrylamides, are easily prepared in two steps from glucose without protection. The complete structural analysis of these compounds by 1D and 2D NMR spectroscopy shows the existence of a rotational isomerism that is strongly dependent on the steric hindrance of the carbonyl substituent: whatever the alkyl chain length, both endo and exo rotamers are observed for N-alkylglucosylacrylamides 1 while the endo rotamer is the sole species observed in the case of N-alkylglucosylmethacrylamides 2. For acrylamido derivatives 1, the exo-endo equilibrium is solvent-dependent: the endo isomer is favored in polar nonaqueous solvents (endo-exo isomeric ratio R = 70/30) while the equilibrium is shifted toward the exo rotamer in protic acidic medium (R = 50/50 in water and 80/20 in acidic medium). An intramolecular hydrogen bond is assumed to be responsible for the increased stability of the endo rotamer. Furthermore, for tetra-O-acetylated derivatives the exo rotamer becomes favored in aprotic solvents. Surface tension measurements demonstrate that N-octyl- to -tetradecyl-substituted compounds 1 and 2 are surfactants with critical micelle concentrations ranging from 1.2 x 10(-2) to 1.7 x 10(-5) mol/L.

Oil-in-water microemulsions of mixtures of styrene and comonomer are easily prepared using titration methods in the presence of nonionic (NPn) or anionic (SDS) surfactants. Functionalized nanoparticles in the 20–30-nm diameter range bearing chloromethyl, active-ester, acid or pyridyl surface end-groups are prepared by polymerization of microemulsions containing mixture of styrene (St) and, respectively, vinylbenzylchloride (VBC), N -acryloyloxysuccinimide (NHA), methacrylic acid (MA) or vinylpyridine (VP). Reactions of nucleophiles on particles bearing either chloromethyl or active-ester surface end-groups, performed directly in the aqueous suspensions, give rise to a wide range of nanoparticles with various functionalities. The main role of the surfactant on such surface reactions is demonstrated and used to improve the reaction yields.

The polymerization of styrene-in-water microemulsions prepared using polymerizable cosurfactants, such as hydroxyalkyl acrylates or methacrylates, gives rise to stable suspensions of well-defined h...

Microheterogeneous catalytic systems using aqueous suspensions of rhodium particles are proved to be efficient for alkene hydrogenation in biphasic liquid-liquid medium provided that the method of stabilization and the interfacial phenomena are properly chosen and controlled. Aqueous supensions stabilized by specially designed trianionic molecules or by hydrophilic polymer (PVA) have been studied. A series of trisulfonated molecules 1 with modulated solution behaviors (surfactant or hydrotrope) depending on the nature of the substituents has been used to stabilize aqueous suspensions of oxidized (polar) or reduced (non polar) rhodium particles. Stabilization of polar particles occurs whatever the substituents when stabilization of metallic apolar particles requires surfactants bearing a significant lipophilic part. In the former case, highly stable suspensions of rhodium nanoparticles with controlled size are obtained in micellar solutions. Both oxidized and reduced rhodium suspensions efficiently catalyzed octene hydrogenation in liquid-liquid medium and it is established that high activity and possible recovery and recycling of the catalyst can be achieved by the control of interfacial parameter e.g. the interfacial tension. In the same way, common polymer-protected colloidal suspensions of Rh(0) particles are proved to efficiently catalyze hydrogenation in two liquid phases systems provided that optimized amounts of surfactants are added to reduce the interfacial tension without emulsification. From these results a relationship between interfacial tension and catalytic activity in biphasic system is proposed.

Much research on organic advanced materials is currently focused on reducing the size of optical devices and fluorescent probes, and, moreover, on avoiding the photobleaching processes which hinder their extensive use for durable devices. To fulfil both goals, we propose the encapsulation of the laser dye pyrromethene 567 in small (

8 pages; International audience; We present a simple and rapid procedure for producing polymer-coated substrates that can be easily functionalized by ion-chelating proteins. The procedure consists of depositing 18 nm metal-chelating cyclam-modified polymer nanoparticles (cyclam-nps) onto a conductive substrate (an Indium Tin Oxide (ITO) electrode) from an aqueous dispersion of Cu2+-loaded cyclam-nps while being subjected to a direct current (DC) field. The density of deposited nps as measured by AFM is shown to be in direct correlation to the concentration of nps in the dispersion with deposition of the particles taking less than 5 s. Because of the functionalization of the nps with cyclam groups, they can be used as anchoring sites for 6-Histidine (6-His) tagged proteins through complexation with divalent metal ions. In this work 6-His Green Fluorescent Protein (6-His GFP) is used as a model protein. The characterization by fluorescence microscopy clearly shows that the protein affinity was ion dependent and that the 6-His GFP density can be controlled by np density, which is itself easily tunable. AFM observations confirmed the immobilization of 6-His GFP onto cyclam-nps and its subsequent removal by treatment with ethylenediaminetetraacetic acid (EDTA).

Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength.

Azobenzene-coated polymer nanoparticles in the 16-nm-diameter range act as phototriggered nanomotors combining photo to kinetic energy conversion with optical control through light intensity gradients. The grafted dyes act as molecular propellers: their photoisomerization supplies sufficient mechanical work to propel the particles in an aqueous medium toward the intensity minima with velocities of up to 15 μm/s. It is shown that nanoparticles can be driven over tens of micrometers by translating the intensity gradients in the plane. The analysis of the particles motion demonstrates the decisive role of photoisomerization in the transport with a measured driving force that is 3 to 4 orders of magnitude higher than optical forces.

PPH 3 reacts with activated alkynes in reverse (water-hydrocarbon) microemulsions giving specifically rise to a mixture of Z and E triphenylvinylphosphonium salts which are readily isolated in good yields.

The regioselective addition of diphenylphosphine on conjugated olefins leads to new hydrophilic phosphines. Ligands with various functional groups (carboxylic, sulfonate, trimethylammonium and hydroxy) and their neutral and cationic rhodium complexes have been prepared and characterized.

Bis-tetraazacyclotetradecanes (bis-cyclam) are readily prepared with fairly good yields in a one step procedure from non-protected cyclam. The synthesis involves a selective addition of cyclam on bis-acrylamides in chloroform in the presence of one equivalent of p-toluenesulfonic acid.

Catalytic oxidation of alkanes occurs in reverse (water in oil) microemulsions stabilized by an anionic surfactant (Aerosol OT®). The catalytically active microemulsion is generated by mixing two reverse microemulsions containing respectively an aqueous solution of iron (FeII or FeIII) and an aqueous solution of H2O2 (30%) dispersed in liquid alkanes (continuous oil phase). This microemulsion system is active in the CH bond oxidation of various liquid alkanes (cycloalkanes, decalin, tetralin, alkylbenzenes) into ketones and secondary and tertiary alcohols at room temperature. The selective oxidation of secondary carbons into ketones and tertiary carbons into alcohols is interpreted by the intervention of iron(V) oxene intermediates rather than radical Fenton-type mechanisms. Polynuclear aggregates such as colloidal hydrous ferric oxides generated by hydrolysis within the aqueous microdroplets are assumed to be the catalytically active species. In fact, we demonstrate that previously prepared iron oxide colloids (Fe2O3 and FeOOH) similarly catalyze the oxidation of alkanes with hydrogen peroxide in reverse microemulsions. The low interfacial water—hydrocarbon tension and the very high interfacial area in liquid—liquid dispersions greatly favour the catalytic process.

Optically pure (S) ethyl-2-hexan-1-ol (S) 4 is prepared for the first time from (S) ethyl-2-hexanoic acid. Nucleophilic addition of sodium bisulfite on the bis [(S) ethyl-2-hexyl] maleate gives rise to an equimolar mixture of two optically active sodium bis [(S) ethyl-2-hexyl] sulfosuccinates diastereoisomers. The critical micelle concentration of these new optically active surfactants is almost identical to those of the well known racemic ĺdAerosol OTŕd

A neat water-based thermoregulated system for Pd-catalyzed Heck reactions is described. It uses a thermo-responsive ligand L that enables (1) the transfer of the catalyst in the organic phase upon heating thus allowing the reaction to take place in one phase, and (2) the separation/recovery of the catalyst in the water phase upon cooling and hence catalyst reuse. The amphiphilic ligand L with an inverse temperature-dependent solubility in water is prepared by covalent attachment of 2,2′-dipyridylamine to the tip of a nonionic polyoxyethylene surfactant (decyloctaethyleneglycol C10E8). Spectroscopic studies reveal that the amphiphilic dipyridyl-based ligand L forms a 1 : 1 Pd complex (PdLCl2) in organic solvent and a 1 : 2 Pd complex in water. Cross-coupling reactions of iodobenzene with ethyl acrylate and styrene are achieved, without any organic solvent, at 100–120 °C with sodium carbonate as a base using 0.1 to 0.5 mol% of Pd catalyst generated in water from L and Na2PdCl4. The reaction products, trans-cinnamic acid and stilbene, are readily isolated at room temperature, and the catalyst is recovered in the aqueous phase, without the need to add any organic solvent. The aqueous phase can be used in three catalytic runs with an almost constant catalytic activity for the coupling of iodobenzene with ethyl acrylate.

PPH 3 reacts with activated alkynes in reverse (water-hydrocarbon) microemulsions giving specifically rise to a mixture of Z and E triphenylvinylphosphonium salts which are readily isolated in good yields.

The title compound, C(61)H(68)F(8)O(2)S(2), is a photochromic liquid crystal based on diaryl-ethene as photoswitchable unit. The F atoms connected to the benzene rings are disordered over two positions; the site-occupation factors refined to 0.830 (3)/0.170 (3). The mol-ecule adopts a photo-active anti-parallel conformation and the distance between the two reactive C atoms of the thio-phene rings is 3.448 (3) Å. The dihedral angles between the central cyclo-pentene ring and the adjacent thio-phene rings are 43.56 (3) and 48.58 (3)°. These structural elements exhibit a suitable geometry for photochromic behaviour in the crystalline state.

International audience; A simple synthesis of polymer core-dendrimer shell nanoparticles (NPs) in the 15-20-nm-diameter range is presented. Amine-terminated polypropyleneimine (PPI) dendrimers DAB-dendri-(NH2)(4) and DAB-dendri-(NH2)(16) (DAB4 and DAB16) are covalently attached to the surface of primary polystyrene-based NPs bearing reactive chlorobenzyl groups produced by microemulsion polymerization in the presence of a cationic surfactant. The grafting readily proceeds under mild conditions and leads to translucent aqueous suspensions of core-shell-type NPs with a high density of peripheral amine groups that have been characterized relative to their size and chemical composition. The dendritic shell acts as a protective ionizable outer layer and provides an improvement of the colloidal stability in neutral and acidic media. The metal-binding capacity of the PPI dendrimers is retained, and spectrophotometric titrations show that the dendrimer-grafted NPs can trap a large number of Cu2+ ions (more than 900 Cu per NP-DAB16). These properties make them potentially valuable templates for the elaboration of hybrid nanomaterials. The reactivity of the external amine groups is used to link covalently azobenzene chromophores (disperse Red 1 residues) through aza-Michael addition in aqueous suspension. This simple method gives access to colored NPs with high dye contents in the outer layer (up to 1000-1500 dye molecules per NP), which indicates that dendrimer-functionalized NPs are valuable building blocks for the construction of multifunctional nanomaterials.

Vinyl tridecafluorohexyl sulfoxide 1 and sulfone 2 are shown to be highly reactive towards Michael addition with a broad range of secondary and primary amines. Full selectivity for monofunctionalization of primary amines can be achieved by a proper choice of reagent 1 or 2 depending on amine basicity.

Latex nanoparticles functionalized with cyclam (1,4,8,11-tetraazacyclotetradecane), a copper chelator, have been doped with a fluorescent dye (BODIPY derivative: 4,4-difluoro-8-(2',4',6'-trimethyl)phenyl-2,6-diethyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene). The bulky, hydrophobic fluorophore dissolves within the nanoparticles' polymer core up to a concentration of about 88.4 micromol g(-1). At this concentration the fluorescence yield is about 0.80. Adding Cu2+ ions to the solution decreases the fluorescence because of the energy transfer between the dye and the violet copper cyclam complexes. The response is fast: 90% of the quenching occurs within 1 s. The Cu2+ detection threshold is of 1 nanomolar. No interferences were observed with zinc and nickel ions.

New functional thermoreversible metal complexing surfactants consisting of a chelating amino acid residue grafted to the tip of a nonionic surfactant [alkyl poly(oxyethylene) CiEj] or in a branched position are studied. Nonionic surfactants are thermoreversible and exhibit a clouding phenomenon associated with phase separation of micelles. The functional molecules retain both the surface-active properties and the characteristic thermoreversible behavior. Because of the hydrophilic contribution of the chelating group (acetyl lysine), the cloud point and the area at the air-water interface are higher for functional surfactants than for nonionic precursors. These new surfactants have efficient complexing properties toward metal ions and are more efficient than the mixture of the corresponding nonionic surfactant and the acetyl lysine ligand solubilized in micelles. This reveals the synergistic effect obtained by the covalent link between the two functions. Addition of a bulky group on classical amphiphilic structures modifies markedly the packing constraints at the origin ofmicellar structures. Small-angle X-ray or neutron scattering results, modeled jointly on the absolute scale, demonstrate the influence of unrecognized lithium nitrate (LiNO3) as well as specifically recognized uranyl nitrate [UO2(NO3)2] salts on micellar structure and phase boundaries. The determination of the micellar shape variations induced by a recognized salt, that is, a decrease of the polar headgroup, allows the rationalization of uncommon synergistic effects on the cloud point variation: increase with lithium nitrate, no decrease in the presence of uranyl nitrate, and a very large decrease when these two salts are present together.

A fluorescent sensor for Cu(2+) at the nanomolar level in water has been designed by associating a BODIPY fluorophore and a selective ligand (cyclam) in ultrafine polymer nanoparticles.

A straightforward grafting of a polycationic phosphorus-containing dendritic shell onto polystyrene nanoparticles leads to dendronized nanoparticles showing unique behavior.