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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.

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).

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.

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).

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.

Embedded electronics, particularly power modules, allows management of electric energy and therefore development of “carbon-free” vehicle. However, these electronic components, will shortly be located near heat engine automotive, and they must withstand various environments and sometimes, hard stresses (humidity, chemical aggression (oil), vibrations…). But actual encapsulation materials are not today efficient enough to match with these future imposed stresses. Thus, the aim of this work is to develop new encapsulation polymers. For this, two types of crosslinked Silicone/Polyurethane (Si/PU) copolymers were “solvent-free” synthesized and with short polymerization times.A first series of materials Si/PU containing between 55 and 76%wt silicone units were synthesized by alcool-iscyanate polyaddition from silicone precursor, synthesized or commercial, and a pluri-isocyanate, in the presence of catalyst. A second series of copolymers, Silicone/Polyhydroxyurethane (Si/PHU) containing 26 and 61%wt silicone units, was obtained without isocyanate or catalyst from poly(dimethylsiloxane) biscyclocarbonate and a triamine.Mechanical and thermal properties as well as hydrophobic character of all materials were evaluated. In order to improve thermal properties and decrease the cost of encapsulation resin, inorganic fillers were blended in some of Si/PU polymers.The most interesting materials were tested as encapsulant in power modules, and the first electrical measurements during thermal cyclings were very promising, L’électronique embarquée, notamment les modules de puissance, permet la gestion de l’énergie électrique et donc le développement de véhicules « décarbonés ». Toutefois, en vue d’être positionnés près du moteur thermique, ces composants électroniques devront résister à des environnements très divers et parfois à de sévères contraintes (humidité, agression chimique (huiles), vibrations…). Or, les matériaux d’encapsulation qui les protègent ne sont pas, aujourd’hui, assez performants pour répondre à ces nouvelles contraintes. Ainsi, le but de ces travaux de thèse est donc de développer de nouveaux polymères d’encapsulation. Pour cela, deux types de copolymères Silicone/Polyuréthane (Si/PU) réticulés ont été synthétisés, sans solvant, et avec des temps de polymérisation courts.Une première série de matériaux Si/PU contenant entre 55 et 76%m de motif silicone, a été synthétisée par polyaddition alcool-isocyanate à partir de précurseurs silicone, synthétisés ou commerciaux, et d’un pluriisocyanate, en présence d’un catalyseur. Une seconde série de copolymères Silicone/Polyhydroxyuréthane (Si/PHU) contenant 26 et 61%m de motif silicone a été obtenue sans isocyanate et sans catalyseur, à partir de poly(diméthylsiloxane) biscyclocarbonate et d’une triamine.Les propriétés mécaniques, thermiques et le caractère hydrophobe de tous ces matériaux ont été évalués. Dans le but d’améliorer les propriétés thermiques et de diminuer le coût de la résine d’encapsulation, des charges inorganiques ont été incorporées à certains polymères Si/PU.Les matériaux les plus intéressants ont été testés comme encapsulant dans des modules de puissance et les premières mesures électriques au cours de cyclages thermiques sont très prometteuses.