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Deschenaux, Robert

Nom
Deschenaux, Robert
Affiliation principale
Fonction
Professeur.e ordinaire
Email
Robert.Deschenaux@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/384
_
0000-0002-1142-0022

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  • Publication
    Métadonnées seulement
    Novel Fullerene Containing Liquid Crystalline Dendrimers and Hemi-dendrimers: Synthesis and Characterization
    (2004)
    Deschenaux, Robert 
    ;
    Yevlampieva, Natalia
    ;
    Dmitrieva, Tatyana
    ;
    Dardel, Blaise
    ;
    Lavrenko, Peter
    Novel fullerene C60 contg. liq. cryst. dendrimers and hemi-dendrimers have been characterized by the method of electro-optical Kerr effect and detn. of the permanent dipole moment, sensitive to the mol. polar ordering and anisotropy of polarizability, and by hydrodynamic methods in soln. An influence of the covalently bonded fullerene on the polarity, electro-optical, and viscometric properties of fullerene derivs. have been detected, analyzed, and concluded that fullerene produces a change in the original ordering in dendritic mols., which mainly resulted in correction of the shape asymmetry of these mols. as a whole. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Electro-optical behavior of fullerene-containing liquid-crystalline dendrimers in solutions
    (: American Chemical Society, 2003)
    Yevlampieva, Natalia P.
    ;
    Lavrenko, Peter
    ;
    Dardel, Blaise
    ;
    Deschenaux, Robert 
    The synthesis of multifunctional materials performed by multicomponent single mols. of special chem. architecture is one of the modern trends in materials science. In the present work, malonate dendrimers have been used as matrix mols. for the synthesis of novel liq. cryst. (LC) materials with covalently linked fullerene C60 as addnl. functional component. Two purposes have been realized in the mol. design of novel LCs: 1) combination of typical mesogene compds. as the end groups with dendritic structure of the matrix mol., and 2) incorporation of fullerene to LC mols. Electrooptical Kerr effect and hydrodynamic methods have been utilized to study the dendritic samples with a variable fullerene position for examg. the influence of fullerene on the mol. properties of the original LC dendrimers. It was detected that substituted fullerene C60 reinforces the electrooptical effect of LC dendrimers and only slightly changes their size and mobility in soln. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Amphiphilic and mesomorphic fullerene-based dendrimers
    (2003)
    Guillon, Daniel
    ;
    Nierengarten, Jean-Francois
    ;
    Gallani, Jean-Louis
    ;
    Eckert, Jean-Francois
    ;
    Rio, Yannick
    ;
    del Pilar Carreon, Maria
    ;
    Dardel, Blaise
    ;
    Deschenaux, Robert 
    Growing attention is currently devoted to large dendritic structures for applications in nanotechnol. and materials science. In this respect, the incorporation of such compds. into thin ordered films appears to be an important issue. One of the most widely pursued approaches to structurally ordered dendrimer assemblies was the prepn. of Langmuir films at the air-water interface. We report on the case of a diblock globular fullerene-based dendrimer and show that peripheral substitution of the dendrimer with hydrophobic chains on one hemisphere and hydrophilic groups on the other provides the required hydrophobic/hydrophilic balance allowing the formation of stable Langmuir films. A second approach was to consider the case of fullerene contg. dendrimers terminated by mesogenic groups such as cyanobiphenyl subunits. Whatever the generation is, up to the fourth one, all these compds. exhibit a well-defined liq. cryst. smectic A phase. The mol. organization within the smectic layers is monolayered or bilayered depending on the generation. For the smallest dendrimers, the organization is mainly governed by the size of the fullerene moiety, whereas for the higher ones, it is governed by the interactions between the terminal mesogenic groups. These two approaches appear particularly interesting for functional groups such as fullerenes, which are not well adapted to be organized in nanoscale architectures. The present study shows that fullerenes can indeed be introduced into different types of ordered structure when they were chem. adequately modified. 3',3''-(Methanoxymethano[1,3]benzenomethanoxymethano)-3'H,3''H-dicyclop ropa[1,9:3,15][5,6]fullerene-C60-Ih-3',3''-dicarboxylic acid. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Electrooptical behavior of fullerene-containing liquid-crystalline dendrimers in solutions
    (2003)
    Yevlampieva, Natalia P.
    ;
    Dardel, Blaise
    ;
    Lavrenko, Peter
    ;
    Deschenaux, Robert 
    Mesomorphic fullerene derivs. of dendritic structure were studied in solns. by the method of electrooptical Kerr effect, hydrodynamic methods (translation diffusion and viscometry) and by the method of dielec. polarization of the solns. The influence of covalently bonded fullerene C60 on the polarity, electrooptical and hydrodynamic properties of fullerene contg. samples was obsd. in comparison with fullerene free analogs. The change of mol. form asymmetry for fullerene-contg. dendritic compds. was detected. Properties of the dendritic mols. depend on fullerene position in their structure and hemi-dendrimers are more sensitive to the incorporation of fullerene than dendrimers. [on SciFinder(R)]
  • Publication
    Accès libre
    Dendrimères liquides-cristallins du fullerène: synthèse, propriétés et organisation supramoléculaire
    (2002)
    Dardel, Blaise
    ;
    Deschenaux, Robert 
    Le but de cette thèse est la synthèse de dendrimères mésomorphes contenant du fullerène C60 et l'étude de la relation entre leurs propriétés liquides-cristallines et leur structure. Ce travail est divisé en trois parties : i) La première partie porte sur l'étude de dendrimères aryles polyesters à chaînes terminales contenant du cyanobiphényle. La synthèse de plusieurs générations successives de dendrimères a eu pour but de mettre en évidence une relation entre les propriétés liquides-cristallines et la structure moléculaire. La méthode de synthèse choisie a été la méthode convergente, en utilisant comme unité de greffage un coeur de type malonate. La préparation des dendrimères jusqu'à la quatrième génération nous a permis d'étudier les relations entre la structure et les propriétés en fonction du dégré de ramification. ii) La deuxième partie présente la synthèse et l'étude de dendrimères non-symétriques contant des groupes cyanobiphényles et des chaînes terminales alkyles. L'objectif a été de préparer des molécules non-symmétriques en se basant sur les dendrimères de la première partie de ce travail, et d'en étudier les propriétés liquides-cristallines en fonction du nombre de génération des dendrons greffés sur le coeur. iii) La troisième partie porte sur la synthèse et l'étude des propriétés liquides-cristallines de dendrimères contenant du fullerène dans le coeur ainsi qu'un carbone asymétrique dans les chaînes terminales. L'objectif a été, pour commencer cette étude, de synthétiser des dendrimères racémiques et d'en étudier les propriétés liquides-cristallines en fonction de la structure et de la génération. Il a été montré que la présence du fullerène induit des phases smectiques A par modification de l'organisation moléculaire pour les petites générations. Cependant, avec l'augmentation de la génération, l'influence du fullerène faiblit considérablement et les dendrimères forme de toute façon des phases smectiques A. Les résultats obtenus laissent entrevoir la possibilité de modifier l'organisation moléculaire, par un choix approprié de la structure de la molécule, dans la perspective de pouvoir contrôler son organisation, The goal of this work is the synthesis of mesomorphic fullerene-containing and the study of the relationship between their liquid-crystalline properties and their structure. This work is divided into three parts: i) The study of alkyle-terminated cyanobiphenyle-containing polyester aryle. The synthesis of several dendrimer generations allowed us to show a relationship between the liquid-crystalline properties and the molecular structure. The synthetic method used was a convergent dendrimer synthesis using a malonate as core. Preparation of such dendrimers up to the fourth generation allowed to study the relationships between structure and properties as a function of the degree of branching. ii) The synthesis and the study of non-symmetrical cyanobiphenyle- and terminal alkyle chains-containing dendrimers. The goal was to prepare non-symmetrical molecules based upon the dendrimers from the first part of this work and to study their liquid-crystalline properties as a function of the generation number of the different dendrons. iii) The synthesis and the study of the liquid-crystalline properties of fullerene-containing dendrimers that possess an asymmetrical carbon in the terminal chains. To begin this study the goal was to synthesize racemic dendrimers and to study their liquid-crystalline properties as a function of the structure and the generation. It was shown that the fullerene induces smectic A phases by modifying the molecular organisation for low generations. However, the influence of the fullerene moiety decreases with increasing generation and dendrimers tend to naturally form smectic A phases. Our results indicate there is a possibility to modify the molecular organisation by an appropriate choice of the molecular structure, which would allow control over the organisation
  • Publication
    Accès libre
    Fullerene-containing liquid-crystalline dendrimers
    (2001)
    Dardel, Blaise
    ;
    Guillon, Daniel
    ;
    Heinrich, Benoît
    ;
    Deschenaux, Robert 
    Addition reaction of mesomorphic malonate-based dendrimers (up to the fourth generation) with C60 gave liquid-crystalline fullerene derivatives. The cyanobiphenyl unit was used as liquid-crystalline promoter. The malonates presented nematic and/or smectic A phases. The fullerenes showed only smectic A phases, with the exception of the second generation dendrimer for which smectic A and nematic phases were observed. The supramolecular organization of the fullerene-based molecular units within the smectic A layers was investigated by X-ray diffraction. Two structural regimes were determined. For the low generation dendrimers, the supramolecular organization is determined by steric factors. For the high generation dendrimers, the mesogenic groups impose a microphase organization: due to lateral extension of the branching part of the molecule, the cyanobiphenyl groups arrange in a parallel fashion as in classical smectic A phases, the rest of the macromolecule being located between the mesogenic sublayers.
  • Publication
    Accès libre
    Synthesis, Characterization, and Mesomorphic Properties of a Mixed [60]Fullerene−Ferrocene Liquid-Crystalline Dendrimer
    (1999)
    Dardel, Blaise
    ;
    Deschenaux, Robert 
    ;
    Even, Michael
    ;
    Serrano, Elisabeth
    Addition reaction of the malonate-based second-generation ferrocene-containing liquid-crystalline dendrimer 16 to [60]fullerene led to the title compound 1. Molecule 1 showed good solubility in common organic solvents and good thermal stability. Examination of its mesomorphic properties revealed the presence of an enantiotropic smectic A phase, which was identified by polarized optical microscopy from the observation of typical focal−conic and homeotropic textures. The dendritic addend 16 exhibited similar properties as those of the fullerene-based dendrimer. The results described in this report open the way to the elaboration of fullerene-containing liquid-crystalline macromolecules.