Comme un roman, Impressions

Comme un roman – On ne lit plus !– Qui crée donc les réfractaires à la lecture ?– La télévision Pennac dit « STOP » : « J'accuse », non à l'injustice ! Dans son essai Comme un Roman il redonne à chacun sa part de responsabilités. Pauvre télé, bouc émissaire attitré… Les réels saboteurs de lecture potentiels sont les « 31 faut lire », les pavés des programmes scolaires, ces bonnes intentions dictatoriales qui brandissent la littérature comme un bagage pour…« On ne lit pas pour, mais contre »...

L'introduction des didacticiels «génétique» dans l'enseignement de premier cycle universitaire : Conditions d'utilisation, résultats d'observations et d'enquêtes

Le travail présenté ici concerne l'introduction de didacticiels de génétique fondamentale dans l'enseignement de premier cycle universitaire scientifique. Nous rapportons l'analyse des résultats d'enquêtes réalisées auprès d'étudiants et d'enseignants de deux universités françaises utilisatrices des didacticiels. Ces résultats nous ont conduits à la définition des conditions nécessaires à une utilisation satisfaisante des didacticiels. Ces enquêtes font apparaître les caractéristiques de ce nouvel outil de travail. Les observations que nous avons faites lors de l'utilisation des didacticiels révèlent des éléments nouveaux dans ce type d'enseignement; on assiste en particulier à une redéfinition des rôles respectifs des étudiants et des enseignants

Liquid crystal properties resulting from synergetic effects between non-mesogenic organic molecules and a one nanometre sized octahedral transition metal cluster.

International audienceThis work presents the synthesis and studies of a red-NIR luminescent liquid crystal compound based on an octahedral metallic cluster core orthogonally bounded to six non-mesogenic organic ligands. It evidences synergetic effects between the organic and inorganic parts of the hybrid, resulting in the generation of liquid crystal properties on cooling from the isotropic melt

From metallic cluster-based ceramics to nematic hybrid liquid crystals: a double supramolecular approach.

International audienceWe describe a new supramolecular approach combining host-guest and electrostatic interactions to design hybrid materials containing polyanionic bulky inorganic compounds and showing liquid crystalline properties

Enhancement of smectic C mesophase stability by using branched alkyl chains in the auxiliary ligands of luminescent Pt(II) and Pd(II) complexes.

International audienceA novel series of Pd(II) and Pt(II) complexes based on cyclometallated imine ligands and N-benzoylthiourea (BTU) derivatives as auxiliary ligands has been prepared and their liquid crystalline properties as well as photophysical properties have been investigated. The crystal structure of one cyclometallated Pt(II) complex with N-(p-F-phenyl)-N'-benzoylthiourea as a co-ligand has been solved. The liquid crystalline properties have been investigated by a combination of DSC, POM and variable temperature powder X-ray diffraction. These new metallomesogens display either a monotropic SmC phase or both SmA and SmC phases, depending on the number of alkoxy groups attached to the imine ligand, alkyl chain length or the use of branched alkoxy terminal groups. We found that the introduction of branched alkoxy terminal groups lead to lower transition temperatures and stabilization of the SmC phase in both the Pd(II) and Pt(II) complexes. While the Pd(II) complexes display no emission, the Pt(II) complexes show good emission properties in solution, in the solid state and as a PMMA film at room temperature, and their investigation is reported

Deep red luminescent hybrid copolymer materials with high transition metal cluster content

Accepted 04 Dec 2013International audienceThe hybrid strategy is a powerful approach to design functional materials by combining inorganic dyes with an organic matrix. However, introducing high contents of inorganic species within the hybrid material is a real challenge that requires a perfect balance between the interactions of both components to avoid mainly phase segregation problems. Based on our demonstration on an anionic molybdenum cluster, we present a general method to introduce high contents of such class of nanometre sized inorganic molecular deep red dyes in a polymer matrix. Our strategy exploits the physical interactions between the organic and inorganic parts of the hybrid material and allows a high cluster rate to be introduced (up to 50 wt%) in the polymer matrix. The resulting hybrids are remarkably stable even after several months of ageing. Moreover, the Mo clusters maintain their intrinsic deep red luminescence properties while the polymer organic matrix fully maintains its processability, thanks to the di-anionic character of the Mo6 clusters. Such materials show promising prospects in applications needing deep red emitters

Design and Integration in Electro-Optic Devices of Highly Efficient and Robust Red-NIR Phosphorescent Nematic Hybrid Liquid Crystals Containing [Mo6I8(OCOCnF2n+1)6]2− (n = 1, 2, 3) Nanoclusters

International audienceBy combining [Mo6I8(C n F2n+1COO)6]2- (n = 1, 2, 3) nanocluster units with liquid crystalline ammonium cations, a new series of hybrid materials is developed that show a nematic liquid crystal phase, the most fluid of all LC phase, on a large range of temperatures including room temperature. The photophysical studies performed in the LC state show that these self-assembled hybrid materials emit in the red-NIR with absolute quantum yields up to 0.7 and show a very good photostability under continuous irradiation. They are further integrated up to 20 wt% in E7, a well-known nematic commercial LC mixture. Mixtures are investigated in terms of homogeneity and stability to select the best suitable candidate for the design of electro-controlled devices. Studies of optical switching, contrast, viscosity, and behavior toward an electrical stimulus demonstrate the high potential of these hybrid materials in the fields of photonic or optoelectronic

Advances in the Engineering of Near Infrared Emitting Liquid Crystals and Copolymers, Extended Porous Frameworks, Theranostic Tools and Molecular Junctions Using Tailored Re6 Cluster Building Blocks

International audienceAt the occasion of the fiftieth birthday of the introduction of the term 'metal atom cluster' by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the engineering of molecular assemblies and nanomaterials based on octahedral Re6 metal atom clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic-inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped [(Re6Yi8)Ya6] cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form [(Re6Yi8)La6] (L = CN, OH, various organic ligands...). This work reports advances in the synthesis of [(Re6Yi8)Ya6] and [(Re6Yi8)La6] cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions

Practice and organisation of measuring in experimental work during the first two years at the Paris XI -Orsay University : Comparative analysis in biology, chemistry and physics

Ce travail présente la comparaison de pratiques d'enseignement expérimental au niveau du premier cycle universitaire, en biologie, chimie et physique à Orsay (Université Paris Sud, France). Cette comparaison est effectuée en décrivant les activités offertes aux étudiants. Nous proposons une lecture de ces activités traduisant l'intention didactique d'une formation à la démarche expérimentale. Nous décrivons et analysons comment cette interprétation peut amener les étudiants à effectuer la mise en relation des différents éléments du mesurage : protocole expérimental, appareillage, résultats de mesure, lois ou modèles, valeurs de référence. Nous précisons ainsi les activités intellectuelles et pratiques, et les compétences et savoirs enjeu dans cette mise en relation. Ceci permet de dégager les similitudes des pratiques d'enseignement expérimental et les particularités disciplinaires. L'interprétation proposée fait apparaître une potentialité intéressante des TP : l'enseignant peut placer l'étudiant dans une situation de mise en relation critique des éléments du mesurage, l'amenant à porter un jugement argumenté sur ses résultats

Photoluminescent materials based on PMMA and a highly-emissive octahedral molybdenum metal cluster complex

Materials that combine photoluminescence, optical transparency and facile processability are of high importance in many applications. This article reports on the development of photoluminescent poly(methyl methacrylate) materials based on novel highly emissive anionic molybdenum cluster complex [{Mo6I8}(OTs)6]2- (where OTs- is the p-toluenesulfonate ion). The materials were obtained by both solution and bulk copolymerisation of methyl methacrylate and (dMDAEMA)2[{Mo6I8}(OTs)6], where dMDAEMA+ is the polymerisable cation [2-(methacryloyloxy)ethyl]dimethyl-dodecylammonium. Evaluation of the resultant hybrid materials showed that one could combine the excellent photoluminescent properties of the cluster complex with the transparency and processability of PMMA