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Deschenaux, Robert

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

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  • Publication
    Métadonnées seulement
    Macrocyclic Effects in the Mesomorphic Properties of Liquid-Crystalline Pillar[5]- and Pillar[6]arenes
    (2013)
    Nierengarten, Iwona
    ;
    Guerra, Sebastiano 
    ;
    Holler, Michel
    ;
    Karmazin-Brelot, Lydia
    ;
    Barbera, Joaquin
    ;
    Deschenaux, Robert 
    ;
    Nierengarten, Jean-Francois
    Whereas the reaction of 1,4-bis(2-bromoethyloxy)benzene (4) with paraformaldehyde in the presence of BF3·Et2O afforded exclusively the cyclopentameric pillar[5]arene deriv. (5), both cyclopenta- and cyclohexameric macrocycles 5 and 6 were obtained when the reaction of 4 with paraformaldehyde was performed at 45 °C in CHCl3 with FeCl3 as the catalyst. Treatment of compds. 4-6 with sodium azide provided the corresponding polyazides, to which a cyanobiphenyl building block was subsequently grafted to generate model compd. 1, pillar[5]arene 2, and pillar[6]arene 3, bearing two, ten and twelve mesomorphic subunits, resp. The liq.-cryst. and thermal properties of the compds. were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Comparison of the liq.-cryst. properties of macrocycles 2 and 3 with those of 1 revealed the strong influence of the macrocyclic pillar[n]arene core on the mesomorphic properties. Whereas only a monotropic mesophase was obsd. for 1, a broad enantiotropic mesophase was evidenced for both pillar[n]arene derivs. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Design of liquid-crystalline gold nanoparticles by click chemistry
    (2012)
    Mischler, Sylvain 
    ;
    Guerra, Sebastiano 
    ;
    Deschenaux, Robert 
    Mesomorphic alkyne-based 1st- and 2nd-generation dendrons were grafted onto Au nanoparticles carrying azide groups under click reaction conditions. The nanoparticles decorated with the dendrons displayed liq.-cryst. properties and good thermal stability. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Fullerene-containing dendrimers: synthesis and properties
    (2012)
    Nierengarten, Jean-Francois
    ;
    Holler, Michel
    ;
    Deschenaux, Robert 
    A review. The aim of this review is not to give an exhaustive review on fullerene-contg. dendrimers but to present examples to illustrate the current state-of-the-art of fullerene chem. for the development of new functional dendrimers. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Building liquid crystals from the 5-fold symmetrical pillar[5]arene core
    (2012)
    Nierengarten, Iwona
    ;
    Guerra, Sebastiano 
    ;
    Holler, Michel
    ;
    Nierengarten, Jean-Francois
    ;
    Deschenaux, Robert 
    Comparison of the liq.-cryst. properties of a pillar[5]arene core functionalized with 10 mesogenic cyanobiphenyl units with those of a corresponding model compd. revealed the strong influence of the macrocyclic pillar[5]arene core on the mesomorphic properties. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    A liquid-crystalline fullerene-oligophenylenevinylene dyad which displays columnar mesomorphism
    (2011)
    Hoang, Thi Nhu Y.
    ;
    Pociecha, Damian
    ;
    Salamonczyk, Miroslaw
    ;
    Gorecka, Ewa
    ;
    Deschenaux, Robert 
    The design, synthesis and liq.-cryst. properties of a family of hybrid compds. which are built from rod-like (oligophenylenevinylene) and disk-like [poly(benzyl ether)] units are reported. All compds. form columnar phases within broad temp. ranges; the mesophases are stable even below room temp. Weak photovoltaic effect was obsd. for the C60-OPV dyad. For the mol. having a terminal OH group, frustration of the hexagonal packing was obsd. and gave rise to a rare phase sequence. For this material, a columnar phase with trigonal symmetry and doubling of the crystallog. lattice was found below the hexagonal columnar phase. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Accordion-optimized DEPT experiments
    (2010)
    Furrer, Julien
    ;
    Guerra, Sebastiano 
    ;
    Deschenaux, Robert 
    In this contribution, a pulse sequence is described for recording accordion-optimized DEPT experiments. The proposed ACCORDEPT experiment detects a wide range of one-bond coupling constants using accordion optimization. As a proof of concept, this strategy has been applied to a mesogen containing a large range of one-bond (1)J(CH) coupling constants associated with the various structural elements. The ACCORDEPT experiment afforded significant enhancements for the resonances with the larger (1)J(CH) couplings, similar SNR for aliphatic resonances, but reduced SNR for aliphatic resonances as compared with the standard DEPT experiment. In addition, the ACCORDEPT is straightforward to implement, does not require any supplementary calibration procedures and can be used under automated conditions without difficulty by inexperienced users. Copyright © 2010 John Wiley & Sons, Ltd.[on SciFinder (R)]
  • Publication
    Métadonnées seulement
    Diastereoisomerically Pure Fulleropyrrolidines as Chiral Platforms for the Design of Optically Active Liquid Crystals
    (2010)
    Campidelli, Stephane
    ;
    Bourgun, Philippe
    ;
    Guintchin, Boris
    ;
    Furrer, Julien
    ;
    Stoeckli-Evans, Helen 
    ;
    Saez, Isabel M.
    ;
    Goodby, John W.
    ;
    Deschenaux, Robert 
    Incorporation of [60]fullerene (C60) within self-organizing systems is conceptually challenging but allows us to obtain materials which combine the characteristics (anisotropy, organization) of condensed mesophases with the properties of C60 (photo- and electrochem. activity). Here, the authors report on the synthesis, characterization, and liq.-cryst. properties of four optically active fullerodendrimers, which are chiral at the point of conjunction between the fullerene scaffold and the mesogenic moieties. Thus, the novelty of this study is to take advantage of the asym. carbon atom created during the 1,3-dipolar cycloaddn. reaction on C60 in order to induce mesoscopic chirality in the materials. Four diastereoisomeric fulleropyrrolidines ((R,S)-1, (R,R)-1, (S,R)-1, and (S,S)-1) were synthesized and assocd. with a second-generation nematic (N) dendron to give fullerodendrimers ((R,S)-2, (R,R)-2, (S,R)-2, and (S,S)-2) which display chiral nematic (N*) phases. The abs. configurations of the stereogenic centers were detd. by X-ray crystallog., 1D and 2D NMR expts., and CD spectroscopy. The liq.-cryst. properties of the fullerodendrimers were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The fulleropyrrolidine derivs. 2 exhibit supramol. helicoidal organizations with a right-handed helix for the (R,S)-2 and (R,R)-2 diastereoisomers and a left-handed helix for the (S,R)-2 and (S,S)-2 diastereoisomers. This result suggests that the self-organization of such supermol. materials can be controlled at the mol. level by the introduction of only one chiral center. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Influence of a mesogenic dendrimer on the morphology of polymer-fullerene composites for photovoltaics
    (2010)
    Kasdorf, Olga
    ;
    Kitzerow, Heinz-Siegfried
    ;
    Lenoble-Zwahlen, Julie
    ;
    Deschenaux, Robert 
    The efficiency of bulk heterojunction-type plastic solar cells depends on the morphol. of an entangled network of 2 immiscible compds. that serve as electron donor and electron acceptor. Results are presented on how the luminescence and the morphol. of a composite contg. a fullerene C60 deriv. and a p-phenylene vinylene (PPV) deriv. are altered, when a dendrimer with a fullerene core and mesogenic side-chains, is added. Fluorescence quenching and surface topog. of the composites indicate that adding the mesogenic dendrimer can result in smaller domain sizes, which may be useful for photovoltaic applications. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Mesomorphic Metallo-Dendrimers Based on the Metal-Metal Bonded Ru2(CO)4 Sawhorse Unit
    (2008)
    Frein, Stephane
    ;
    Auzias, Mathieu
    ;
    Sondenecker, Aline
    ;
    Vieille-Petit, Ludovic
    ;
    Guintchin, Boris
    ;
    Maringa, Natacha
    ;
    Süss-Fink, Georg 
    ;
    Barbera, Joaquin
    ;
    Deschenaux, Robert 
    Dinuclear Ru complexes contg. the stable metal-metal bonded Ru2(CO)4 sawhorse unit with two dendritic carboxylato bridges were synthesized and characterized. All complexes Ru2(CO)4(O2CR)2L2 (R = R1, R2, R3) contg. cyanobiphenyl-based poly(arylester) dendrons of 1st (R1), 2nd (R2), and 3rd (R3) generation and PPh3, pyridine, or 4-picoline ligands L proved to be mesomorphic, giving rise to smectic A or smectic A and nematic phases. The supramol. organization within the smectic A phase is governed by the nature and structure of the mesogenic units and dendritic core. Such materials are of interest for the design of catalytically active anisotropic fluids. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    High-Resolution Characterization of Liquid-Crystalline [60]Fullerenes Using Solid-State Nuclear Magnetic Resonance Spectroscopy
    (2008)
    Dvinskikh, Sergey V.
    ;
    Yamamoto, Kazutoshi
    ;
    Scanu, David
    ;
    Deschenaux, Robert 
    ;
    Ramamoorthy, Ayyalusamy
    Liq.-cryst. materials contg. fullerenes are valuable in the development of supramol. switches and in solar cell technol. In this study, we characterize the liq.-cryst. and dynamic properties of fullerene-contg. thermotropic compds. using solid-state natural abundance 13C NMR expts. under stationary and magic angle spinning sample conditions. Chem. shifts spectra were measured in isotropic, liq.-cryst. nematic and smectic A and cryst. phases using one-dimensional 13C expts., while two-dimensional sepd. local-field expts. were used to measure the 1H-13C dipolar couplings in mesophases. Chem. shift and dipolar coupling parameters were used to characterize the structure and dynamics of the liq.-cryst. dyads. NMR data of fullerene-contg. thermotropic liq. crystals are compared to that of basic mesogenic unit and mesomorphic promoter compds. Our NMR results suggest that the fullerene-ferrocene dyads form highly dynamic liq.-cryst. phases in which mols. rotate fast around the symmetry axis on the characteristic NMR time scale of ?10-4 s. [on SciFinder(R)]