Deschenaux, Robert

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)]

2005, Campidelli, Stephane, Lenoble, Julie, Barbera, Joaquin, Paolucci, Francesco, Marcaccio, Massimo, Paolucci, Demis, Deschenaux, Robert

[60]Fullerene-contg. liq.-cryst. dendrimers were synthesized from the first to the fourth generation by applying the 1,3-dipolar cycloaddn. reaction from a mesomorphic dendritic-type aldehyde deriv., sarcosine (N-methylglycine) or glycine and C60. The cyanobiphenyl unit was used as a liq.-cryst. promoter. With the exception of the first-generation fullerene dendrimer, which was found to be nonmesomorphic, all fullerene-based dendrimers gave rise to a smectic A phase. The liq.-cryst. fullerenes led to two different supramol. organizations within the smectic layers: for the second-generation dendrimers, the mols. are oriented in a head-to-tail fashion within the layers; for each mol. the cyanobiphenyl units point in the same direction. For the dendrimers of third and fourth generations, the dendritic core extends laterally, parallel to the layer planes; the mesogenic units are oriented above and below the dendritic core. For the aldehyde precursors, only one organization inside the layers was obtained, similar to the one obsd. for the third and fourth fullerene-based dendrimers. Cyclic voltammetry investigations displayed several one-electron and multielectron redn. processes; no significant interaction in the ground state between the fullerene and the dendrimer was noticed. The title compds. showed the typical electrochem. stability of fulleropyrrolidines. [on SciFinder(R)]

2008, Frein, Stephane, Boudon, Julien, Vonlanthen, Mireille, Scharf, Toralf, Barbera, Joaquin, Süss-Fink, Georg, Burgi, Thomas, Deschenaux, Robert

Liq. cryst. dendrons carrying either a thiol or disulfide function which display nematic, smectic A, columnar, or chiral nematic phases have been synthesized. Their mesomorphic properties are in agreement with the nature of the mesogenic units and structure of the dendrons. The first-generation poly(aryl ester) dendron contg. two cyanobiphenyl mesogenic units was used to functionalize gold nanoparticles. For full coverage, a smectic-like supramol. organization on the nanometer scale is obsd., when the gold nanoparticles are spread onto carbon-coated copper grids. This results indicates that the dendritic ligands reported here act as self-organization promoters. [on SciFinder(R)]

2005, Campidelli, Stephane, Perez, Laura, Rodriguez-Lopez, Julian, Barbera, Joaquin, Langa, Fernando, Deschenaux, Robert

First- and second-generation ferrocene-based dendrimers, fullerene and a second-generation liq.-cryst. poly(aryl ester) dendrimer carrying four cyanobiphenyl units were assembled to elaborate polyfunctional materials displaying mesomorphic and electronic properties. The targeted compds. gave rise to enantiotropic smectic A phases and organized into bilayer structures within the smectic layers. Cyclic voltammetry investigations revealed oxidn. and redn. processes in agreement with the presence of both ferrocene and fullerene units. Finally, strong quenching of the fluorescence was obtained for the fullerene-ferrocene dyads suggesting efficient electron transfer from the ferrocene-based dendrimer to fullerene. [on SciFinder(R)]

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)]

2004, Campidelli, Stephane, Vazquez, Ester, Milic, Dragana, Prato, Maurizio, Barbera, Joaquin, Guldi, Dirk M., Marcaccio, Massimo, Paolucci, Demis, Paolucci, Francesco, Deschenaux, Robert

The 1,3-dipolar cycloaddn. reaction was used to assemble fullerene, ferrocene and a 2nd-generation liq.-cryst. cyanobiphenyl-based dendrimer. The targeted compd. displayed an enantiotropic smectic A phase from 40 to 135°. The d-layer spacing was detd. by x-ray diffraction, and is independent of temp. with a value of 95 Å. Mol. modeling and structural considerations suggested partial bilayer organization of the mesogenic mol. units within the smectic layers. Oxidn. or redn. processes of the basic components (ferrocene, fullerene, dendrimer) were studied by electrochem. techniques, and were in agreement with the structure. Photoinduced electron transfer from ferrocene to fullerene was identified, most likely with a through space mechanism. [on SciFinder(R)]