Vignette d'image

Deschenaux, Robert

Nom
Deschenaux, Robert
Affiliation principale
Fonction
Professeur ordinaire
Email
Robert.Deschenaux@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/384

Résultat de la recherche

Filtres

13
76
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 10 sur 13
  • Publication
    Métadonnées seulement
    Ferrocene-containing liquid-crystalline dendrimers
    (2003)
    Chuard, Thierry
    ;
    Beguin, Maria-Teresa
    ;
    Deschenaux, Robert 
    The synthesis and liq.-cryst. properties of two ferrocene-contg. liq.-cryst. dendrimers of second generation were described, which differentiate by the position of the ferrocene unit within the structure and by the nature of the mesomorphic promoters. Both dendrimers gave rise to smectic phases in agreement with their structures. The title compds. were prepd. by applying a convergent synthesis. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Functional liquid-crystalline materials based on ferrocene
    (2003)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    A review. Ferrocene is a valuable unit for the elaboration of functional liq.-cryst. materials: (1) its 3-dimensional structure allowed a clear structure-mesomorphic behavior relation in the case of mono-, di-, and poly-substituted ferrocene-contg. liq. crystals to be established, (2) its derivatization at the 1,3-positions by 2 different substituents generated structures with planar chirality, and (3) its redox properties could be used to produce redox-active mesomorphic liq. crystals. [on SciFinder(R)]
  • Publication
    Accès libre
    Design, mesomorphic properties, and supramolecular organization of [60]fullerene-containing thermotropic liquid crystals
    (2002)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    Two concepts have been developed for the design of [60]fullerene-containing thermotropic liquid crystals, namely, the covalent and non-covalent concepts. In the covalent approach, C60 was functionalized with liquid-crystalline addends (malonate and aldehyde derivatives) by applying either the Bingel reaction or the 1,3-dipolar cycloaddition reaction. In the non-covalent approach, a liquid-crystalline inclusion complex was obtained from mesomorphic cyclotriveratrylene (CTV) derivatives and C60. All of the covalent C60 derivatives showed smectic A phases. In one case, an additional nematic phase was detected. The [C60(CTV)2] complex gave rise to nematic-like and cubic phases. The covalent and non-covalent approaches demonstrate the various possibilities for C60 to give rise to mesomorphic materials.
  • Publication
    Accès libre
    Electrochemical properties of a liquid-crystalline mixed fullerene–ferrocene material and related species
    (2002)
    Carano, Maurizio
    ;
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    ;
    Even, Michael
    ;
    Marcaccio, Massimo
    ;
    Paolucci, Francesco
    ;
    Prato, Maurizio
    ;
    Roffia, Sergio
    The electrochemical properties of a fullerene–ferrocene liquid crystal are reported. The electrochemical study was carried out under strictly aprotic conditions: a total of seven reduction peaks were detected in the negative potential region, and two oxidation peaks in the positive potential one. Comparison of the data with those obtained from suitable model compounds (i.e., analogous fullerene- or ferrocene-free materials ) has allowed the assignment of all reduction and oxidation steps. The CV study evidenced the occurrence of a fast follow-up chemical reaction coupled to the third (at 25 °C) or fourth (at –60 °C) reduction of either 1 or 3. Such a reaction, presumably related to the cleavage of one of the cyclopropane bonds, is quantitatively reversed upon re-oxidation. Conversely, under bulk electrolysis conditions (second reduction), the species undergo the retro-Bingel reaction, i.e. the irreversible removal of the bis(alkoxycarbonyl)methano adducts to give the parent C60.
  • Publication
    Métadonnées seulement
    Liquid-crystalline dendrimers based on ferrocene and fullerene
    (2001)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    The synthesis and liq.-cryst. properties of a 2nd generation ferrocene-contg. liq.-cryst. dendrimer, and the liq.-cryst. behavior of a 2nd generation mixed fullerene-ferrocene liq.-cryst. dendrimer are presented. The electrochem. properties were also studied. Both compds. gave rise to smectic A phases, which were identified by polarized optical microscopy and DSC. The liq.-cryst. behavior is detd. by the cholesterol units which were selected as mesomorphic promoters. Therefore, both compds. display similar liq.-cryst. properties. [on SciFinder(R)]
  • Publication
    Accès libre
    Amphiphilic Fullerene-Cholesterol Derivatives: Synthesis and Preparation of Langmuir and Langmuir-Blodgett Films
    (2001)
    Felder, Delphine
    ;
    Carreón, Maria del Pilar
    ;
    Gallani, Jean-Louis
    ;
    Guillon, Daniel
    ;
    Nierengarten, Jean-François
    ;
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    Amphiphilic fullerene bis-adducts 11 and 14 containing two and four cholesterol moieties, respectively, were prepared starting from the corresponding bis-malonate derivatives. In a systematic study, their spreading behavior at the air-water interface was compared to that of bis-adduct 6 with no polar head-group. Compared to 6, for which some three-dimensional aggregation occurs, the polar head-group in 11 and 14 is responsible for an attractive interaction with the aqueous subphase, forcing the molecules towards the water surface into a two-dimensional arrangement. Even if homogeneous Langmuir films were obtained with both 11 and 14, only the films of 14 show a reversible compression/expansion behavior. This suggests that, by increasing the number of cholesterol subunits, the encapsulation of the C-sphere in its addend is more efficient, thus preventing fullerene-fullerene interactions and aggregation phenomena. The Langmuir films of 11 and 14 were also efficiently transferred onto hydrophilic quartz slides, yielding Langmuir-Blodgett films.
  • Publication
    Métadonnées seulement
    Amphiphilic fullerene-cholesterol derivatives: synthesis and preparation of Langmuir and Langmuir-Blodgett films
    (2001)
    Felder, Delphine
    ;
    Carreon, Maria Del Pilar
    ;
    Gallani, Jean-Louis
    ;
    Guillon, Daniel
    ;
    Nierengarten, Jean-Francois
    ;
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    Amphiphilic fullerene bis-adducts 11 and 14 contg. two and four cholesterol moieties, resp., were prepd. starting from the corresponding bis-malonate derivs. In a systematic study, their spreading behavior at the air-H2O interface was compared to that of bis-adduct 6 with no polar head-group. Compared to 6, for which some three-dimensional aggregation occurs, the polar head-group in 11 and 14 is responsible for an attractive interaction with the aq. subphase, forcing the mols. towards the H2O surface into a two-dimensional arrangement. Even if homogeneous Langmuir films were obtained with both 11 and 14, only the films of 14 show a reversible compression/expansion behavior. This suggests that, by increasing the no. of cholesterol subunits, the encapsulation of the C-sphere in its addend is more efficient, thus preventing fullerene-fullerene interactions and aggregation phenomena. The Langmuir films of 11 and 14 were also efficiently transferred onto hydrophilic quartz slides, yielding Langmuir-Blodgett films. [on SciFinder(R)]
  • Publication
    Accès libre
    Planar chirality: a fascinating symmetry breaking which leads to ferroelectricity in ferrocenyl liquid crystals
    (2000)
    Chuard, Thierry
    ;
    Cowling Stephen J.
    ;
    Fernandez-Ciurleo, Maria
    ;
    Jauslin, Isabelle
    ;
    Goodby, John W.
    ;
    Deschenaux, Robert 
    We describe the synthesis, characterization and properties of the first optically-active 1,3-unsymmetrically disubstituted ferrocene derivative which is to exhibit smectic C* and smectic A* phases.
  • Publication
    Métadonnées seulement
    A liquid-crystalline hexa-adduct of [60]fullerene
    (1999)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    ;
    Hirsch, Andreas
    ;
    Schonberger, Hubert
    A hexa-adduct of [60]fullerene was synthesized by addn. of a mesomorphic twin cyanobiphenyl malonate deriv. to C60; whereas the malonate deriv. gave a monotropic nematic phase, the fullerene hexa-adduct showed an enantiotropic smectic A phase. [on SciFinder(R)]
  • Publication
    Accès libre
    A liquid-crystalline hexa-adduct of [60]fullerene
    (1999)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    ;
    Hirsch, Andreas
    ;
    Schönberger, Hubert
    A hexa-adduct of [60]fullerene was synthesized by addition of a mesomorphic twin cyanobiphenyl malonate derivative to C60; whereas the malonate derivative gave a monotropic nematic phase, the fullerene hexa-adduct showed an enantiotropic smectic A phase.