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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
    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
    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
    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
    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
    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.
  • Publication
    Accès libre
    First Fullerene[60]-Containing Thermotropic Liquid Crystal. Preliminary Communication
    (1996)
    Chuard, Thierry
    ;
    Deschenaux, Robert 
    The synthesis and liquid-crystalline and thermal properties of a fullerene[60] functionalized by a framework containing two cholesterol derivatives through a methanofullerene structure are reported. The targeted fullerene derivative showed high thermal stability.