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Whereas their para homologs are not mesogenic, the disk-shaped triphenyltriazine meta-trialkylesters obtained via trimerization of 3-cyanobenzoic alkylester, which are configurationally more flexible, exhibit a monotropic nematic mesophase. Introduction of fluorine atoms into the alkyl chains or into the phenyl moieties leads to the appearance of an enantiotropic columnar mesophase. If fluorine is introduced both in the chains and in the phenyl moieties, only a monotropic mesophase remains. Fluorination of either the alkyl chains or the aromatic core, but not both, appears thus as a simple means of inducing or stabilizing columnar self-assembly in disk-shaped systems. As the homeotropically alignable columnar mesophase can thus be made to persist at room temperature, as energies higher than 3 eV of the first excited triplet state are computed in agreement with the value reported for the parent arene, and as they are not fluorescent themselves, these compounds are of promise as aligning host matrices for blue-emitting TADF devices with improved light outcoupling. Dilution of a columnar with a nonmesogenic homolog induces the nematic state, indicating that the nanoscopic make-up of both mesophases is closely related.

[Cu II (enpnen)] 2 [Mo IV (CN) 8 ]•7H 2 O (enpnen = N,N ′-bis(2-aminoethyl)-1,3-propanediamine) molecular cluster compound (1) was subject to a series of irradiations with the light of 405 nm. On irradiation isothermal magnetization at 1.8 and 5 K in the field range 0-70 kOe as well as magnetic susceptibility in the temperature range of 2-300 K were subsequently detected. Both types of magnetic signals were next an

In this work, we explored the effect of an applied electric field on the molecular conformation of two weak polyelectrolytes grafted on gold electrodes: poly(acrylic acid) and the weak polybase poly(2-(dimethylamino)ethyl methacrylate), by combining Quartz Crystal Microbalance with an electrochemical setup. Our results indicate that different mechanisms influence the response of weak polyelectrolytes to an externally applied potential difference, including electrochemical modification of the local pH by oxygen reduction and the electrostatic interaction between the metallic electrode and the charged monomers and ions in solution. Our results evidence that fine control of polymer conformation can be readily obtained at low applied potentials, opening pathways for precise, localized control of surface properties. However, these applications require considering the history-dependent behavior of polyelectrolyte brushes, hysteresis in the response and the influence of electrochemical reactions driven by potential changes.

The aim of this chapter is to propose a step-by-step approach for the study of emulsions stabilized by particles independently of the system chemical nature. This includes tools as simple as macroscopic observations of the obtained emulsions up to more sophisticated techniques, like electron microscopy or interfacial rheology. The progressive characterization allows collecting information at different length scales; at the level of the emulsion properties, at the level of drops and down to the particle packing at the oil-water interface, highlighting interaction between either drops and adsorbed particles. The link between the various length scales is also enhanced. For example, bridging of particles adsorbed at the interface of neighboring drops is responsible for the adhesion between drops leading to a plug flow that can be assessed by naked eyes. Therefore, the chapter pretends to be a general guideline for studying a new unknown system, starting from scratch.

International audience; Ce chapitre traite des matériaux polymériques électrostrictifs. Les questions fondamentales et les applications prometteuses seront traitées. Les récentes avancées en direction des matériaux à électrostriction géante dans le domaine seront passées en revue et certains obstacles de longue date à leurs applications pratiques seront également évoqués.

We investigate the anomalous dynamics in smectic phases of short host rods where, counter-intuitively, long guest rod-shaped particles diffusive faster than the short host ones, due to their precise size mismatch. In addition to the previously reported mean-square displacement, we analyze the time evolution of the Self-van Hove functions G(r,t), as this probability density function uncovers intrinsic heterogeneous dynamics. Through this analysis, we show that the dynamics of the host particles parallel to the director becomes non-gaussian and therefore heterogeneous after the nematic-to-smectic-A phase transition, even though it exhibits a nearly diffusive behavior according to its mean-square displacement. In contrast, the non-commensurate guest particles display Gaussian dynamics of the parallel motion, up to the transition to the smectic-B phase. Thus, we show that the Self-van Hove function is a very sensitive probe to account for the instantaneous and heterogeneous dynamics of our system, and should be more widely considered as a quantitative and complementary approach of the classical mean-square displacement characterization in diffusion processes., 10 pages, 9 figures, the article has been accepted by the Journal of Chemical Physics

Agarose hydrogels are poroviscoelastic materials that exhibit a waterlogged-crosslinked microstructure. Despite an extensive use in biotechnologies and numerous studies of the elastic properties of agarose gels, little is known about the compressible behavior and the microstructural changes of such fibrillar hydrogels under compression. The present work investigates the mechanical response of centimeter-sized pre-molded agarose cylinders when applying a compressive strain ramp over an extended range of loading speed and polymer concentration. One of the original contributions is the simultaneous monitoring of the changes in the hydrogel volume to determine the Poisson’s ratio through a spatiotemporal method. The linear poroelastic response of agarose hydrogels shows a compressible behavior at strain rates less than 0.7 % s−1. The critical compressive strain of a few percent at the onset of the non-linear regime and the always positive Poisson’s ratio decrease when applying a slow compressive ramp. The mechanical response in the linear regime is typical of a deformation mode either dominated by the bending of semiflexible strands (enthalpic regime) or by the stretching of the network (entropic regime) at higher agarose concentration. Cyclic linear shear deformations superimposed to a compressive strain from 0.5 up to 40% further give evidence of a compression-softening of the network causing the transition to the non-linear regime without dependence upon the network topology and connectivity. Finally, the buckling-induced aging of the network under a weak compression and the poroviscoelasticity of the hydrogel are shown to impact the relaxation of the normal stress and the equilibrium stress.

International audience; Efficient generation of anti-Stokes emission within nanometric volumes enables the design of ultracompact, miniaturized photonic devices for a host of applications. Many subwavelength crystals, such as metal nanoparticles and two-dimensional layered semiconductors, have been coupled with plasmonic

International audience; Hypothesis: The stability of emulsions stabilized by soft and responsive microgels and their macroscopic properties are governed by the microstructure of microgels, in particular their deformability. However, little is known about the role of the microgel chemistry, though it is expected that polymeric backbone with an amphiphilic structure is a requirement for their adsorption at the oil-water interface.Experiments: A series of biocompatible, thermoresponsive and amphiphilic poly(oligoethylene glycol)methacrylate (pOEMA) microgels is synthesized, with varying hydrophobic-hydrophilic balance, or equivalent varying volume phase transition temperature (VPTT). Their behavior in the bulk phase and at solid interfaces is compared to their behavior at liquid interfaces, studied on flat and model interfaces by the pendant drop method, and on drops, in microgel-stabilized emulsions.Findings: Controlling the composition of microgels by simply changing the number of ethylene oxide in the hydrophilic side chain allows a precise tuning of their VPTT in the range of 20 to 60°C. Simultaneously, the swelling ratio and the deformability of the microgels increase by increasing the hydrophilicity, as a result of the polymerization process. Regardless of their hydrophilicity, all the swollen pOEMA microgels adsorb at the liquid interface and stabilize emulsions, whose flocculation state and mechanical stability depends on the microgel deformability. Unexpectedly, most emulsions remain stable upon heating above the VPTT of the microgels. Such feature highlights their extreme robustness, whose origin is discussed. This study opens new opportunities for the use of biocompatible Pickering emulsifiers.

International audience; Integrating high-loading dielectric nanoparticles into polar polymer matrices potentially can profit the intrinsic polarization of each phase and allow for greatly enhanced dielectric properties in polymer nanocomposites. It is however challenging to achieve desirable highly filled polar polymer composites because of the lack of efficient approaches to disperse nanoparticles and maintain interfacial compatibility. Here, we report a versatile route to fabricate highly filled barium titanate/fluorinated silicone rubber (BT/FSR) nanocomposites by ''thiol-ene click'' and isostatic pressing techniques. The loaded BT nanoparticles (from 82 wt.% to 90 wt.%) are chemically bonded with FSR in the nanocomposites. The existence of the polar group (-CH2CF3) of the polymer matrix does not affect the uniform dispersion of the nanoparticles and the good interfacial compatibility as well. 90 wt.% BT/FSR nanocomposite shows the highest dielectric constant of 57.8 at 10 3 Hz, while the loss tangent can be kept below 0.03. Besides, BT/FSR nanocomposites display the higher breakdown strength than BT/SR nanocomposites, respectively. This work offers a facile strategy towards superior dielectric properties of polymer nanocomposites.

International audience; A goal in the field of nanoscale optics is the fabrication of nanostructures with strong directional light scattering at visible frequencies. Here, we demonstrate the synthesis of Mie-resonant coreshell particles with overlapping electric and magnetic dipole resonances in the visible spectrum. The core consists of silicon surrounded by a lower index silicon oxynitride (SiOxNy) shell with an adjustable thickness. Optical spectroscopies coupled to Mie theory calculations give the first experimental evidence that the relative position and intensity of the magnetic and electric dipole resonances are tuned by changing the core-shell architecture. Specifically, coating a high-index particle with a low-index shell coalesces the dipoles, while maintaining a high scattering efficiency, thus generating broadband forward scattering. This synthetic strategy opens a route towards metamaterial fabrication with unprecedented control over visible light manipulation.

The linear trinuclear complex cation [Fe 3 (DpyF) 4 ] 2+ was prepared as [Fe 3 (DpyF) 4 ](BF 4) 2 . 2CH 3 CN. With large Fe-Fe distances of 2.78 Å, this complex demonstrates intramolecular ferromagnetic coupling between the anisotropic Fe II centers (J/k B = +20.9(5) K) giving an S T = 6 ground state and exhibits single-molecule magnet properties.

International audience; Une nouvelle stratégie pour la synthèse de grands composés aromatiques polycycliques a récemment été développée. Elle fait intervenir une variante de la réaction de Perkin dont le rôle est d'assembler des briques élémentaires, des acides aryle-glyoxyliques et des acides aryle-acétiques, en précurseurs flexibles conjugués et substitués par des fonctions carboxyliques. L'étape finale de rigidification, en formant les liaisons CC manquantes, aboutit alors à des composés aromatiques polycycliques entièrement ou partiellement condensés. La méthode est maintenant au point avec un grand nombre de briques élémentaires accessibles, des techniques de protection des fonctions réactives, et plusieurs exemples de composés finaux de structures très diverses : rubans plans, hélicènes, macrocycles. Mots-clés : Synthèse organique, composés aromatiques polycycliques, nano-rubans, macrocycles, hélicènes.

International audience; Optical metamaterials are artificially engineered architectures that exhibit desired optical properties not found in nature. Bespoke design requires the ability to define shape, size, orientation and composition of material structures on the nanometre length scale. Bottom-up self-assembly methods, such as block copolymer (BCP) templating, offer unique pathways to tailored features, at spatial resolution not routinely achieved by conventional top-down techniques. In this review, we provide the general readership with basic concepts of the underlying fabrication processes and examine optical phenomena arising from BCP-derived metamaterials and nanoresonators, with both dielectric and plasmonic characteristics.

International audience; The concentration and manipulation of light in the nanoscale range are fundamental to nanophotonic research. Plasmonic nanoparticles can localize electromagnetic waves within subdiffraction volumes, but they also undergo large Joule losses and inevitable thermal heating. Subwavelength dielectric nanoparticles have emerged as a new class of photonic building blocks that enhance light-matter interactions within nanometric volumes. These nanoparticles exhibit strong electric and magnetic responses with negligible energy dissipation. In recent decades, the design of efficient dielectric nanoresonators has seen tremendous progress. In this review, we discuss recent theoretical and experimental advances in characterizing the optical properties of dielectric nanoparticles, from resonant single-particle scattering characteristics to multimodal interference in complex particle assemblies. Specific attention is paid to novel strategies employed to manipulate far-field Mie-type scattering, enhance local electromagnetic field, and boost magnetic resonance, as well as ultimately achieve Fano-like resonance, unidirectional scattering (Kerker conditions), and photon waveguide. We also consider the fundamental prospects of designing all-dielectric/metallic-dielectric photonic nanostructures, particularly those functional dielectric materials and all-dielectric three-dimensional assemblies.

International audience; The detection of Pb 2+ was performed using a completely inkjet printed multi-walled carbon nanotube (IJP-MWNT) sensor employing anodic stripping voltammetry (ASV) using Osteryoung square wave stripping voltammetry (OSWV) as the detection step. The MWNT ink was prepared in water using bile salts (BS) as a surfactant, which was further washed out with DI water and then remaining MWNT was used as an electrode surface. The IJP-MWNT electrode was used as the working electrode with a platinum wire and glass capillary Ag/AgCl as auxiliary and reference electrode, respectively. The electrode was optimized in 0.1 M acetate buffer (pH = 4.3) and had a linear range of 5-50 ppb (R 2 = 0.98235) a sensitivity of 20.15 nA/ppb and a limit of detection (LOD) of 1.632 ppb for Pb 2+. The analytical applicability of electrode was tested in a real drinking water sample (i.e.) Cincinnati tap water with a linear range of 15-70 ppb (R 2 = 0.98752) a sensitivity of 2.654 nA/ppb and a LOD of 1.269 ppb for Pb 2+ .

International audience; Existing nanocolloidal optical resonators presenting strong magnetic resonances often suffer from multi-step low yield synthesis routes as well as a limited tunability, in particular in terms of spectral superposition of electric and magnetic resonances, which is the cornerstone for achieving Huygens scatterers. To overcome these drawbacks, we have synthesized clusters of gold nanoparticles using an emulsion-based formulation route. The fabrication technique involved the emulsification of an aqueous suspension of gold nanoparticles in an oil phase, followed by the controlled ripening of the emulsion. The structural control of the assynthesized clusters, of mean radius 120 nm and produced in large numbers, is demonstrated with microscopy and X-ray scattering techniques. Using a polarization-resolved multi-angle light scattering setup, we reach a comprehensive angular and spectroscopic determination of their optical resonant scattering in the visible wavelength range. We thus report on the clear experimental evidence of strong optical magnetic resonances and directional forward scattering patterns. The clusters behave as strong Huygens sources. Our findings crucially show that the electric and magnetic resonances, as well as the scattering patterns can be tuned by adjusting the inner cluster structure, playing with a simple parameter of the fabrication route. This experimental approach allows for the large scale production of nanoresonators with potential uses for Huygens metasurfaces.

International audience; Beyond the peculiar glass transition temperature (Tg) studied extensively for over two decades, we have investigated in this work the variation of the mass density of polymer thin films, a key property barely put forward in the literature. We were able to directly measure the mass density of polystyrene (PS) and poly (methyl methacrylate) (PMMA) thin films as a function of their thickness from accurate Quartz Crystal Microbalance (QCM) dissolution experiments. Depending on the chemical nature of the polymers, the results showed an unambiguous variation of the mass density when the film thickness was reduced: an increase for PS and a decrease for PMMA films. In the last part, we measured the coefficient of thermal expansion (CTE) of both polymers to rationalize the apparent inconsistency of an increase/decrease in the mass density with the commonly observed depression/rise of the Tg of PS/PMMA films. Surprisingly, the coefficient of thermal expansion and the mass density showed a similar variation with thickness, pointing out a clear correlation between the glass transition temperature, the coefficient of thermal expansion and the free volume of the polymer.

Droplet-based microfluidics is extensively and increasingly used for high-throughput single-cell studies. However, the accuracy of the cell counting method directly impacts the robustness of such studies. We describe here a simple and precise method to accurately count a large number of adherent and non-adherent human cells as well as bacteria. Our microfluidic hemocytometer provides statistically relevant data on large populations of cells at a high-throughput, used to characterize cell encapsulation and cell viability during incubation in droplets.

International audience; An innovative trajectory method was developed to analyze the fluctuating motions of photometric patterns in an image sequence to efficiently extract both the 2d displacement field and the diffusion coefficient in the motion direction. Two different experimental situations are investigated, namely the flow of dense granular suspensions in a Couette cell and the drying kinetics of hydrogels.

An octahedral Co(II) complex with N&prime, (2-hydroxybenzylidene)acetohydrazide Schiff base ligand [HL] forms a 3D supramolecular assembly supported by non-coordinating ClO4&minus, ions and H2O molecules. Individual spin centres are non-interacting and give rise to significant spin-orbit coupling, resulting in field induced slow magnetisation relaxation, which is characteristic of Single Ion Magnet (SIM) behaviour.

Since the discovery of graphene oxide (GO), the most accessible of the precursors of graphene, this material has been widely studied for applications in science and technology. In this work, we describe a procedure to obtain GO dispersions in water at high concentrations, these highly dehydrated dispersions being in addition fully redispersible by dilution. With the availability of such concentrated samples, it was possible to investigate the structure of hydrated GO sheets in a previously unexplored range of concentrations, and to evidence a structural phase transition. Tentatively applying models designed for describing the small-angle scattering curve in the Smectic A (or L$_{\alpha}$) phase of lyotropic systems, it was possible to extract elastic parameters characterising the system on the dilute side of the transition, thereby evidencing the relevance of both electrostatic and steric (Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets, Comment: 11 pages, 10 figures

International audience; Plasmonic nanoparticles, particularly gold nanoparticles (GNPs) hold a great potential as structural and functional building blocks for three-dimensional (3D) nanoarchitectures with specific optical applications. However, a rational control of their assembly into nanoscale superstructures with defined positioning and overall arrangement still remains challenging. Herein, we propose a solution to this challenge by using as building blocks: (1) nanometric silica helices with tunable handedness and sizes as a matrix and (2) GNPs with diameter varying from 4 to 10 nm to prepare a collection of helical GNPs superstructures (called Goldhelices hereafter). These nanomaterials exhibit well-defined arrangement of GNPs following the helicity of the silica template. Strong chiroptical activity is evidenced by circular dichroism (CD) spectroscopy at the wavelength of the surface plasmon resonance (SPR) of the GNPs with a anisotropy factor (g-factor) of the order of 1 × 10−4, i.e., 10-fold larger than what is typically reported in the literature. Such CD signals were simulated using a coupled dipole method which fit very well the experimental data. The measured signals are 1−2 orders of magnitude lower than the simulated signals, which is explained by the disordered GNPs grafting, the polydispersity of the GNPs, and the dimension of the nanohelices.....

International audience; We demonstrate a new concept for reconfigurable microfluidic devices from elementary functional units. Our approach suppresses the need for patterning, soft molding and bonding when details on a chip have to be modified. Our system has two parts, a base-platform used as a scaffold and functional modules which are combined by ‘plug-and-play’. To demonstrate that our system sustains typical pressures in microfluidic experiments, we produce droplets of different sizes using T-junction modules with three different designs assembled successively on a 3 × 3 modular scaffold.

International audience

International audience; The assembly of colloidal building-blocks is an efficient, inexpensive and flexible approach for the fabrication of a wide variety of photonic materials with designed shapes and large areas. In this review, the various assembly routes to the fabrication of colloidal crystals and their post-assembly modifications to the production of photonic materials are first described. Then, the emergingapplications of the colloidal photonic structures in various fields such as biological and chemical sensing, anti-reflection, photovoltaics, and light extraction are summarized.

International audience; Droplet-based microfluidic technologies are powerful tools for applications requiring high-throughput, for example, in biochemistry or material sciences.Several systems have been proposed for the high-throughput production of monodisperse emulsions by parallelizing multiple droplet makers. However, these systems have two main limitations: (1) they allow the use of only a single disperse phase; (2) they are based on multiple layer microfabrication techniques. We present here a pipette-and-play solution offering the possibility of manipulating simultaneously 10 different disperse phases on a single layer device. This system allows high-throughput emulsion production using aqueous flow rates of up to 26 ml/h (>110 000 drops/s) leading to emulsions with user-defined complex chemical composition. We demonstrate the multiplex capabilities of our system by measuring the kinetics of b-galactosidase in droplets using nine different concentrations of a fluorogenic substrate.

International audience; A carbon nanotube-based electrode that combines transparency and good conductivity was used for the first time to develop an electrochemiluminescence (ECL) device. It resulted in an excellent material for ECL applications thanks to the very favorable overpotential of amine oxidation that represents the rate-determining step for the signal generation in both research systems and commercialinstrumentation. The use of carbon nanotubes resulted in a ten times higher emission efficiency compared with commercialtransparent indium tin oxide (ITO) electrodes. Moreover, application of this material for proof-of-principle ECL imaging was demonstrated, in which micro-beads were used to mimic a real biological sample in order to prove the possibility of obtaining single cell visualization.

International audience; The growing popularity of lanthanides in molecular magnetism has given rise to new difficulties that must be overcome for the successful determination of the relevant physical quantities necessary to describe single-molecule magnet(SMM) behaviour. For transition metal compounds, the magnetization (typically experimentally obtained as a function of temperature and magnetic field) facilitates the estimation of chemically intuitive parameters, for example, magnetic super-exchange coupling constants and magnetic anisotropy parameters. The easy availability of this information has led to several studies of correlations between chemical structures and magnetic properties. In turn, this work initiated fundamental research in tuning, for instance, 3d metal ion-based SMMs. For lanthanide ions, a similar interest surely exists, but severalproblems arise before a similar level of knowledge can be achieved. First of all, the intrinsic lability of lanthanide ions, combined with the lack of preference for specific coordination geometry and hence the difficulty of accurately predicting coordination geometry, creates a major obstacle for controlling and tuning the synthesis of 4f SMMs [1]. ...

We present a high-throughput droplet-based microfluidic analysis/screening platform for directed evolution of CotA laccase: droplet-based microfluidic modules were combined to develop an efficient system that allows cell detection and sorting based on the enzymatic activity. This platform was run on two different operating modes: the "analysis" mode allowing the analysis of the enzymatic activity in droplets at very high rates (1000 Hz) and the "screening" mode allowing sorting of active droplets at 400 Hz. The screening mode was validated for the directed evolution of the cytoplasmic CotA laccase from B. subtilis, a potential interesting thermophilic cathodic catalyst for biofuel cells. Single E. coli cells expressing either the active CotA laccase (E. coli CotA) or an inactive frameshifted variant (E. coli ΔCotA) were compartmentalized in aqueous droplets containing expression medium. After cell growth and protein expression within the droplets, a fluorogenic substrate was "picoinjected" in each droplet. Fluorescence-activated droplet sorting was then used to sort the droplets containing the desired activity and the corresponding cells were then recultivated and identified using colorimetric assays. We demonstrated that E. coli CotA cells were enriched 191-fold from a 1 : 9 initial ratio of E. coli CotA to E. coli ΔCotA cells (or 437-fold from a 1 : 99 initial ratio) using a sorting rate of 400 droplets per s. This system allows screening of 10(6) cells in only 4 h, compared to 11 days for screening using microtitre plate-based systems. Besides this low error rate sorting mode, the system can also be used at higher throughputs in "enrichment" screening mode to make an initial purification of a library before further steps of selection. Analysis mode, without sorting, was used to rapidly quantify the activity of a CotA library constructed using error-prone PCR. This mode allows analysis of 10(6) cells in only 1.5 h.

International audience; A bimolecular synthetic reaction (imine synthesis) was performed compartmentalized in micrometerdiameter emulsion droplets. The apparent equilibrium constant (Keq) and apparent forward rate constant (k1) were both inversely proportional to the droplet radius. The results are explained by a noncatalytic reaction-adsorption model in which reactants adsorb to the droplet interface with relatively low binding energies of a few kBT, react and diffuse back to the bulk. Reaction thermodynamics is therefore modified by compartmentalization at the mesoscale—without confinement on the molecular scale—leading to auniversal mechanism for improving unfavorable reactions.

9 pages; International audience; G rowing interest in graphene over past few years has prompted researchers to find new routes for producing this material other than mechanical exfoliation or growth from silicon carbide. Chemical vapor deposition on metallic substrates now allows researchers to produce continuous graphene films over large areas. In parallel, researchers will need liquid, large scale, formulations of graphene to produce functional graphene materials that take advantage of graphene's mechanical, electrical, and barrier properties. In this Account, we describe methods for creating graphene solutions from graphite. Graphite provides a cheap source of carbon, but graphite is insoluble. With extensive sonication, it can be dispersed in organic solvents or water with adequate additives. Nevertheless, this process usually creates cracks and defects in the graphite. On the other hand, graphite intercalation compounds (GICs) provide a means to dissolve rather than disperse graphite. GICS can be obtained through the reaction of alkali metals with graphite. These compounds are a source of graphenide salts and also serve as an excellent electronic model of graphene due to the decoupling between graphene layers. The graphenidemacroions, negatively charged graphene sheets, form supple two-dimensional polyelectrolytes that spontaneously dissolve in some organic solvents. The entropic gain from the dissolution of counterions and the increased degrees of freedom of graphene in solution drives this process. Notably, we can obtain graphenide solutions in easily processable solvents with low boiling points such as tetrahydrofuran or cyclopentylmethylether. We performed a statistical analysis of high resolution transmission electronic micrographs of graphene sheets deposited on grids from GICs solution to show that the dissolved material has been fully exfoliated. The thickness distribution peaks with single layers and includes a few doubleor triple-layer objects. Light scattering analysis of the solutions shows the presence of two-dimensional objects. The typical size of the dissolved flakes can be determined by either static or dynamic light scattering (DLS) using models available in the literature for disk-shape objects. Amean lateral size of ca. 1 μmis typically observed.We also used DLS to monitor the reaggregation that occurs as these sensitive solutions are exposed to air. The graphenide solutions reported in this Account can be used to deposit random arrays of graphene flakes and large single flakes of a lateral size of tens of micrometers onto different substrates. Using the graphenide solutions described in this Account, we foresee the large-scale production of graphene-based printings, coatings, and composites.

Les sciences chimiques, en perpetuelle evolution, sont associees a des syntheses de plus en plus complexes et transdisciplinaires. Dans ce contexte, cet article montre comment la chimie integrative parvient a compartimentaliser les reacteurs chimiques au travers de reactions declenchees aux interfaces huile/eau d'emulsions diluees (reacteurs chimiques disperses) et concentrees (reacteurs chimiques en contact). En illustration, quelques exemples non exhaustifs de morphosyntheses de materiaux fonctionnels avances sont donnes, dans les domaines de la biocatalyse heterogene, de la conversion d'energie et du relargage thermostimule de substances d'interet encapsulees.

Les sciences chimiques sont en perpétuelle évolution avec des stratégies de synthèse de plus en plus complexes à vocation émergente inter- et transdisciplinaire. Dans cette configuration, cet article démontre comment la chimie intégrative parvient à positionner les réacteurs chimiques dans l'espace géométrique au travers de réactions chimiques déclenchées aux interfaces huile/eau d'émulsions diluées (réacteurs chimiques discrets) et concentrées (réacteurs chimiques percolés). En illustration, quelques exemples non exhaustifs de morphosynthèse de matériaux fonctionnels avancés sont donnés dans les domaines de la biocatalyse hétérogène, de la conversion d'énergie et du relargage thermostimulé de substances d'intérêt encapsulées.

32 pages; International audience; The pairing of metal-based electrons to form metal-metal bonds in paddlewheel complexes would suggest that this chemistry is limited to diamagnetic complexes. However, a wide variety of paramagnetic complexes exist in this geometry. Whether obtained by oxidation or reduction of the divalent dinuclear species, as a result of degeneracy or neardegeneracy of their metal-based molecular frontier orbitals, or due to unpaired electrons in extended metal atom chains, paramagnetic paddlewheel complexes can be found in each group of the transition series. This review will present some of these molecules, their polynuclear analogues, and their use in supramolecular and extended architectures, with an emphasis on electronic structure.

In this paper, laminar convection flows induced by carbon dioxide absorption are addressed from experimental, numerical and theoretical points of view. A vertical glass tube (of centimetre scale) filled with distilled water is subjected to a sudden increase in the partial pressure of carbon dioxide. As a result of the diffusion of the gas into the unsaturated solution, a thin layer of fluid located underneath the surface becomes heavier. This initial density gradient first destabilizes to form a plume, which goes downwards through the entire cell. After a first transient pulsating regime (periodic succession of such Rayleigh–Bénard plumes), a stationary flow settles in the tube, which is maintained by the constant supply of gas at the surface. At late stages, this stationary regime is followed by an aperiodic regime, which lasts until the complete saturation of the solution (thermodynamic equilibrium). The present study only focuses on the stationary regime, whose characteristics appear to be almost independent of the Bond number and the aspect ratio but strongly dependent on the chemical Rayleigh number. Three decades of Rayleigh numbers are explored using particle image velocimetry measurements, which allows for a precise determination of the scaling exponents for the vertical velocity amplitude and the plume width. The assumption that gravity and a constant pressure gradient balance the viscous effects enables us to derive an analytic expression for the stationary vertical velocity on the axis, which scales as ${\mathit{Ra}}^{2/ 3} \mathop{(\ln \mathit{Ra})}\nolimits ^{1/ 3} $. As a consequence, the width of the plume scales as ${\mathit{Ra}}^{- 1/ 6} \mathop{(\ln \mathit{Ra})}\nolimits ^{- 1/ 3} $ and the mass Nusselt number as $\mathop{(\mathit{Ra}/ \ln \mathit{Ra})}\nolimits ^{1/ 3} $. These scalings are in excellent agreement with the experimental and numerical results. The multiplicative constants of these scalings can also be calculated and show a fairly good agreement if a rigid boundary condition (no-slip) is assumed at the free surface.

Electromagnetic metamaterials are artificial composites, containing resonators and exhiniting opticalproperties which do not exist in a natural state. This thesis is dedicated to the manufacturing and thecharacterization of such materials. Metallic core-shell particles (gold or silver core coated with a silicashell) are assembled by the Langmuir-Blodgett technique to form dense monolayer and multilayernetworks. These nanoparticles play the role of resonators thanks to the presence of the plasmonresonance of the core whereas the silica shell allows a fine control of the distance between themetallic particles. We realized materials whose distance between resonators and metallic fractionvary. The spectrophotometric analyses, in particular reflection at normal incidence, allowed us toextract the optical properties of the materials. We proposed a phenomenological model in which wedefine the permittivity of the effective layer as the permittivity of a homogenous matrix to which aLorentz oscillator is added to describe the presence of the plasmon resonance. We were able toshow experimentally metamaterials with refractive index lower than 1 can be obtained when thefraction of metal in the material is important enough., Les métamatériaux électromagnétiques sont des composites artificiels, constitués de résonateurs etayant des propriétés optiques n'existant pas à l'état naturel. Cette thèse est consacrée à lafabrication et caractérisation de tels matériaux. Pour cela des particules métalliques coeur-écorce(d'or ou d'argent enrobées de silice) sont assemblées par la technique de Langmuir-Blodgett afin deformer des réseaux denses en monocouche et en multicouches. Ces nanoparticules jouent le rôle derésonateurs grâce à la présence de la résonance plasmon et l'écorce de silice permet de contrôler ladistance entre particules. Nous avons ainsi réalisé des matériaux dont la distance entre lesrésonateurs et la fraction métallique varient. Les analyses spectro-photométriques des films obtenus,notamment en réflexion normale, nous ont permis d'extraire les propriétés optiques de nosmatériaux. Pour cela nous avons proposé un modèle phénoménologique dans lequel nousdéfinissons la permittivité de la couche effective comme étant celle de la matrice à laquelle s'ajouteun oscillateur de Lorentz décrivant la présence d'une résonance plasmon. Nous avons pu ainsimontrer expérimentalement qu'il était possible d'obtenir des métamatériaux d'indice de réfractioninférieur à 1 quand la fraction de métal dans le matériau est suffisamment importante.

Wet granular materials are made of solid particles in high concentration, immersed in a viscous fluid. We investigated particle dynamics in a model granular suspension in Couette geometry, at low Reynolds/Taylor numbers for density and non density matched suspension. We used innovated techniques such as: Single Particle Tracking (SPT), Multi Particles Video Trajectography (MPVT) and Concentration Photometry (CP). These experiments allow us to provide information about single and collective motion of grains as well as particle repartition (local volume fraction). We investigated fully 3D velocity profiles in concentrated suspensions, diffusion coefficients, particle fluctuations and recirculation motion, also differential flows. We observe that the flow of non density matched suspensions is localized near the inner cylinder in the low shear rate regime, resulting in a sheared layer only a few particle diameters in thickness, in a way very similar to sheared dry granular materials. At high enough angular velocity, the initially localized flow crosses over to full fluidization: in this regime the granular suspension nearly behaves as a density-matched suspension. Dependence between particles' velocity and associated fluctuation amplitude is evidenced. Experiments as velocity and concentration profiles were compared with theoretical prediction based on the force balance model and different viscometric laws were investigated for normal and shear forces., Une " boue " est constituée de particules submillimétriques immergées dans un fluide. Nous étudions des boues concentrées (ou " pâtes granulaires "), où la concentration en particules est proche du maximum réalisable. Les particules peuvent être plus denses que le fluide, et sédimenter, ou être équilibrées en densité. Ces deux cas sont examinés, à l'aide d'une boue modèle. Nous étudions les écoulements de ces boues dans une cellule de Couette. Les expériences utilisent des méthodes innovantes, permettant de mesurer les vitesses des grains individuellement et collectivement, et les profils de concentration sous cisaillement. Les expériences apportent des informations nouvelles sur les écoulements, comme l'existence de courants de re-circulation. Les résultats sur les vitesses azimutales et concentrations sont en accord avec la théorie de Morris et Boulay d'équilibre des forces normales, pour un rapport convenable des coefficients viscométriques des forces tangentielle et normales.

In this work, we studied variations of the spontaneous emission rate of internal sources used as probes of variations of the local photonic density of states. Materials as diverse as polymers or inorganic disordered media, photonic crystals and plasmonic nanostructures were characterized. Thus, we discuss successively i) changes of spontaneous emission rate of internal sources due to local density variations of the surrounding polymer medium, both below and above the glass transition temperature; ii) changes of the spontaneous emission rate as a result of conformational changes of fluorescent molecules due to movements of surrounding chains, iii) the study of the fluorescence inhibition /exaltation in photonic crystals and iv) the emission in plasmonic nanostructures. Finally, we describe some research perspectives such as i) the development of highly disordered materials to study the phenomena of light localization and random lasers; ii) the development of plasmonic nanostructures combining localized and propagating surface plasmons to generate high Purcell factors in a spectral range either very wide or very narrow and iii) the development of plasmonic structures sensitive to the optical Kerr effect to achieve optical bistables., Dans ce travail, nous avons étudié les modifications du taux d'émission spontanée de sources internes utilisées comme sondes des variations de densités locales d'états photoniques. Des matériaux aussi divers que des milieux désordonnés polymères ou inorganiques, des cristaux photoniques et des nanostructures plasmoniques ont été caractérisés. Ainsi, nous discutons successivement i) les changements des taux d'émission spontanée de sources internes dus aux variations locales de densité du milieu polymère environnant, en dessous et au dessus de la température de transition vitreuse; ii) les changements des taux d'émission spontanée consécutives aux changements de conformation des molécules fluorescentes dus aux mouvements des chaînes environnantes; iii) l'étude de l'inhibition/exaltation de l'émission de fluorescence dans les cristaux photonique et iv) l'émission dans les nanostructures plasmoniques. Finalement, nous décrivons quelques perspectives de recherche telles que i) le développement de matériaux extrêmement désordonnés afin d'étudier les phénomènes de localisation de la lumière et de lasers aléatoires; ii) le developpement des nanostructures plasmoniques combinant plasmons de surface localisés et propagatifs afin de générer des facteurs de Purcell élevés dans une gamme spectrale soit très large soit très étroite et iii) le développement des structures plasmoniques sensibles à l'effet Kerr optique afin de réaliser des bistables optiques.

12 pages; International audience; We numerically investigate and experimentally demonstrate a new route to controllably manipulate the spontaneous decay rate of dipole emitters in coupled plasmonic modes. The structure under investigation is an hexagonal close-packed array of gold core - silica shell nanoparticles (NPs) sandwiched between two gold films. We show that the interaction of localized and propagating surface plasmon polaritons can dramatically enhance the spontaneous emission rate of quantum emitters (rhodamine isothiocyanate) grafted in the NP silica shell. This strong enhancement (70−100 times) further occurs on the whole, broadband emission spectrum (565 nm to 640 nm) of the emitters.

Nos sociétés sont confrontées à une demande croissante en combustibles biosourcés non fossiles. Les biodiesels, obtenus par transestérification de triesters, offrent une alternative réelle. Les réactions de transestérification peuvent être catalysées par des enzymes, les lipases. Nous présentons la synthèse de catalyseurs enzymatiques opérant en flux continu. Ces mousses biohybrides offrent de nombreux avantages, un bon confinement des enzymes, un encombrement stérique minimisé, un transport de masse optimisé, une simplicité de synthèse et de mise en oeuvre. Ces spécificités engendrent, pour la production de biodiesel sur supports biohybrides macroporeux, des activités enzymatiques exaltées, associées à des endurances remarquables de catalyses en flux continu.

7 pages; International audience; Discovered in 1981 by Tanaka and Murao (Agric Biol Chem 45:2383-2384, 1981), bilirubin oxidase (BOD) is a sub-group of multicopper oxidases (MCOs) also utilizing four Cu+/2+ ions. It catalyzes the oxidation of bilirubin to biliverdin, hence the classification of bilirubin oxidase, and has been primarily used in the determination of bilirubin in serum and thereby in the diagnostic of jaundice. Unlike laccases, the most studied MCOs, BODs display a high activity and stability at neutral pH, a high tolerance towards chloride anions and other chelators, and for some species, a high thermal tolerance. Therefore, BODs could potentially be an alternative to laccase which are so far mainly restricted to applications in acid media. Because of growing interest in BODs for numerous applications under mild pH conditions, based on the number of patents and publications published in the last 5 years, here I will summarize the available data on the biochemical properties of BODs, their occurrence, and their possible biotechnological use in (1) the field of Healthcare for the elaboration of biofuel cells or bilirubin sensors or (2) the field of environmentally desirable applications such as depollution, decolorization of dyes, and pulp bleaching.

We describe carbon nanotube (CNT) structures which are used as mechanical sensors, electromechanical actuators and shape memory materials. These structures include CNT mats and fibres of aligned CNTs. Mechanical sensors are based on the piezo-resistivity of the investigated CNT structures. They can be used as embedded sensors for sensing and damage monitoring of composites. CNT can also be used for novel actuator technologies. Indeed CNTs deform in response to charge injection and electrostatic phenomena. They can be stimulated under the form of electrodes in a given electrolyte. CNT structures can generate a large stress because of their stiffness. In other classes of actuating materials, carbon nanotubes can be used as fillers of shape memory polymers (SMPs). SMPs have applications in packaging, biomedical devices, heat shrink tubing, deployable structures, etc. CNTs are ideal materials to improve the stiffness of shape memory polymers, which is critical for achieving large stress recovery. Their electrical conductivity is of particular interest in the engineering of SMPs which can be heated via Joule’s heating and directly stimulated by an electrical current. We review in this chapter the properties of these new functional materials and highlight their potential for future applications.

Water based lubricants are widely used in metal forming processes due to their good cooling and lubrication capabilities. The goal of this work is to correlate the structural properties of the lubricant to its lubricating behaviour. As mixtures of ethylene diamine and fatty acids in water are some of the main ingredients of such lubricants, their phase behaviour and tribological properties are investigated for different compositions. The phase diagram of the model system is established by using optical microscopy of polarisation, small angle X-rays scattering (SAXS) and freeze-fracture transmission electron microscopy (FF-TEM). For a molar ratio between diamine and fatty acids upper to 1, a succession of lamellar, hexagonal and micellar phases is observed with the dilution. A particular attention is turned to the lamellar phase which presents defects close the transition towards the hexagonal phase. According to SAXS, nuclear magnetic resonance and FF-TEM analyses, we propose that their existence is due to a modulation of the bilayer thickness and an increase of the curvature resulted from the evolution of the coupling between the fatty acids polar heads and the amine counterions. The lubricating ability of these phases is then investigated experimentally using an EHL tribometre that simultaneously enables contact visualisation, film thickness and friction measurements in controlled kinematic conditions. The influence of the lubricant structure on its tribological behaviour is revealing: the lowest friction coefficients are obtained with lamellar samples. The organisation in bilayers of the lamellar phase within the contact and its piezoviscous properties can explain its greater load-bearing capacity and its natural predisposition to the reduction of the friction., Les lubrifiants à base aqueuse sont très largement utilisés dans les procédés de mise en forme des métaux comme le tréfilage, car ils combinent d'excellentes capacités calorifiques à de bonnes propriétés tribologiques. L'objectif de ces travaux est d'établir le lien entre l'organisation des molécules en solution dans le lubrifiant et son pouvoir lubrifiant. La démarche expérimentale consiste à déterminer les propriétés structurales et tribologiques d'un système modèle aqueux, composé d'acides gras et d'éthylène diamine, principaux ingrédients des lubrifiants. Le diagramme de phases du système modèle est établi en s'appuyant sur des techniques de microscopie optique de polarisation, diffusion des rayons X aux petits angles (DXPA) et cryofracture. Pour un rapport molaire entre la diamine et les acides gras supérieur à 1, une succession de phases lamellaire, hexagonale et micellaires, biréfringente sous écoulement et isotrope, est observée avec la dilution. Une attention particulière est accordée à la phase lamellaire qui présente des défauts à l'approche de la transition vers la phase hexagonale. Les analyses réalisées en DXPA, cryofracture et Résonance Magnétique Nucléaire relient leur existence à une modulation de l'épaisseur de la bicouche et une augmentation de la courbure liées au couplage entre les acides gras et les contre-ions amines. Les propriétés lubrifiantes de l'ensemble de ces phases sont également comparées à l'aide d'un tribomètre qui réalise un contact entre un disque et une bille sous une cinématique de contact contrôlée, en régime de lubrification élastohydrodynamique. En plus des mesures de frottement, l'observation simultanée du contact permet de suivre la formation du film lubrifiant entre les surfaces et son évolution. L'influence de l'organisation supramoléculaire du lubrifiant sur son comportement est mise en évidence : les échantillons présentant une organisation lamellaire fournissent les meilleurs résultats en termes de réduction du frottement. L'organisation en bicouches de la phase lamellaire au sein du contact et ses propriétés piézovisqueuses peuvent expliquer sa portance accrue et sa prédisposition naturelle à la réduction du frottement.

Carboxylic derivatives of polycyclic aromatics are interesting materials in order to obtain efficient organic solar cells based on liquid crystals: They have adjustable electronic properties depending on the chemical structure, a tendency to form a columnar mesophase over wide ranges of temperatures and often a homeotropic alignment in contact with polar surfaces such as ITO or glass. We show with this thesis that donor-acceptor pairs of roomtemperature columnar liquid crystals with adjusted properties can be obtained in view of efficient exciton dissociation into separate charges at their junction in solar cells., Les dérivés arène-carboxyliques sont des matériaux intéressants dans le but d'obtenir une cellule solaire organique efficace à base de cristaux liquides : Ils présentent à la fois des propriétés électroniques modulables en fonction de la structure chimique, une tendance aux larges plages de températures de présence d'une mésophase colonnaire et souvent un alignement homéotrope au contact de surfaces polaires telles que l'ITO ou le verre. Nous montrons avec cette thèse que des couples donneur-accepteur colonnaires à température ambiante peuvent être obtenus, avec des propriétés suffisamment complémentaires pour prévoir des dissociations d'excitons en charges séparées à leur jonction dans des cellules solaires.

Columnar liquid crystals made of discotic molecules derived from aromatic dyes are promising materials for the realization of photovoltaic devices thanks to their high charge mobility and their capacity to self-organize. In order to benefit from their anisotropic properties, it is necessary to control their organization in thin films. For example, a homeotropic anchoring where the columns are perpendicular to the substrate is required to carry the charges efficiently to the electrodes. Homogeneous homeotropically oriented ultrathin films (approximately 25 nm) have been obtained by an anchoring transition between a solid substrate and a silver cathode. Moreover, a homeotropically oriented bilayer formed by discotic compounds has been achieved. This represents the first proof of principle of an organic heterojunction based on two oriented columnar liquid crystal layers., Grâce à leurs remarquables qualités de transport de charges et d'autoorganisation, les cristaux liquides colonnaires formés de molécules discotiques dérivées de colorants aromatiques sont des candidats prometteurs pour la réalisation de dispositifs photovoltaïques. Pour profiter à bien de ces propriétés, il est indispensable de maîtriser leur organisation en films minces. Un ancrage homéotrope avec les colonnes perpendiculaires au substrat est ainsi nécessaire pour conduire efficacement les charges aux électrodes. Cet alignement a été obtenu par transition d'ancrage entre un substrat solide et une cathode d'argent permettant d'obtenir des films ultra-minces (environ 25 nm d'épaisseur) homogènes orientés. Par ailleurs, une bicouche de composés discotiques intégralement alignée en ancrage homéotrope a été élaborée. A notre connaissance, ce travail constitue la première preuve de faisabilité d'une hétérojonction donneur - accepteur orientée constituée de cristaux liquides colonnaires.

Chemical and self-assembly approaches are increasingly used for the fabrication of nanostructured materials with controlled optical properties.We have considered the simplest case of composite films comprised of a non-structured polymer with spherical gold nanoparticle inclusions, with varied thickness and filling fractions. Optical properties have been studied by means of spectroscopic ellipsometry in the ultraviolet-visible-near infrared range. For thick, three-dimensional films (30-200 nm) with filling fractions below 6%, the behavior of the optical index as a function of the wavelength is well described using a modified Maxwell-Garnett mixing law modified with anisotropic polarisabilities, which accounts for electromagnetic couplings between neighboring particles. Very dense samples with filling fractions up to 30% have also been fabricated, and exhibit near-zero or negative electric permittivities in a finite frequency range. For very thin films (of thickness close to the nanoparticle size), we have shown that the complex optical index is not an intrinsic descriptor of the system and that ellipsometric analysis cannot determine a sample thickness unambiguously. However, the analysis gives access to the particles extinction cross-section : we find that when the particles lie very close to the silicon substrate, experimental values are enhanced compared to theoretical predictions, even taking into account image dipole effects within the substrate. This work has shed light on the relation between the optical properties and the nanostructure of composite films, and opens the way for the fabrication of nanocomposite materials with novel optical properties via chemical routes., Les méthodes de synthèses chimiques et d'auto-assemblage sont aujourd'hui envisagées pour fabriquer des matériaux nanostructurés aux propriétés optiques contrôlées. Nous avons considéré le cas le plus simple de composites combinant un polymère non-structuré et des nanoparticules d'or sphériques, dont nous fabriquons des films d'épaisseur et de fraction volumique en or variables et étudions les propriétés optiques, par ellipsométrie spectroscopique, dans les domaines ultraviolet-visible-proche infrarouge. Pour des films tridimensionnels épais (30-200 nm) de fraction volumique en nanoparticules inférieure à 6%, les variations de l'indice optique avec la longueur d'onde sont bien décrites par une loi de mélange de Maxwell-Garnett modifiée par l'introduction de polarisabilités anisotropes rendant compte du couplage électromagnétique entre particules proches. Des d'échantillons très denses en nanoparticules ont été fabriqués (jusqu'à des fractions volumiques de 30%), et montrent, dans une bande spectrale finie, des permittivités électriques proches de zéro ou négatives. Pour des échantillons très minces (épaisseur de l'ordre de la taille des nanoparticules), nous montrons que l'indice optique complexe n'est plus un descripteur intrinsèque du système et que l'analyse ellipsométrique ne permet pas de déterminer l'épaisseur de manière non-ambigüe. On a accès en revanche à la section efficace d'extinction des particules : lorsque les particules sont déposées très près du substrat de silicium, les valeurs expérimentales sont exaltées par rapport aux valeurs théoriques, même en tenant compte d'effets de dipôles image dans le substrat. Les conclusions de ce travail ont permis d'éclaircir le lien entre les propriétés optiques mesurées et la nanostructure de films composites, et laissent entrevoir la possibilité d'élaborer par voie chimique des matériaux nanocomposites aux propriétés optiques inédites.

6 pages; International audience; In this study we develop a novel approach to tune nanopatterns on fused silica substrates exploiting the polarization dependence of the strongly localized near field of highly ordered triangular nanoparticle arrays. For this purpose such arrays were prepared by nanosphere lithography on fused silica substrates and subsequently irradiated with single 35 fs long laser pulses. The irradiation leads to the excitation of localized surface plasmon polariton resonances, followed by ablation of the nanoparticles and partially of the substrate. By this means, nanostructures were generated on the substrate surface, reflecting the local fields in the vicinity of the triangular nanoparticles. Depending on the applied fluence, small holes as well as extended nanostructures with dimensions well below the diffraction limit have been created. Furthermore, by rotating the linear polarization of the laser light by 90° with respect to the orientation of triangular nanoparticles, different plasmon modes have been excited, which in turn, alter the local field distribution. As a result, either nanochannels or bone like shaped nanogrooves in a chequered structure were generated on the fused silica substrates. Finite-difference time-domain simulations demonstrate, that the results can, in fact, be explained by the enhanced near field distribution, which is dominated by the excitation of localized surface plasmon polariton resonances in the triangular nanoparticles. It is shown, that the fluence and the polarization of the laser light are the key parameters in nanogroove and nanochannel formation.

Residual stress in polymers arises from the freezing of unstable molecular conformations. Residual stress is critical because its relaxation can cause shrinkage, defects, and fractures of polymer materials. The storage of stress is purposely enhanced to develop shape memory materials. Unfortunately, the storage of mechanical stress is still poorly controlled and understood. An approach to sense the storage of stress based on the spectroscopic response of carbon nanotubes is explored. The Raman response of nanotubes exhibits a variable sensitivity to strain when embedded in polymers that have experienced different thermal and mechanical treatments. This unique feature opens up new possibilities for the use of carbon nanotubes as mechanical nanosensors.

4 pages; International audience; Reactions between hexanuclear manganese pivalate with lanthanide salts (chlorides or nitrates), in the presence of potassium hydroxide, 2-pyridylmethanol and sodium azide leads to formation of a new family of hexaheteronuclear manganese-lanthanide clusters.