Vignette d'image

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

Résultat de la recherche

Filtres

1594
8277
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 10 sur 159
  • Publication
    Accès libre
    Amphiphilic Fullerene-Cholesterol Derivatives: Synthesis and Preparation of Langmuir and Langmuir-Blodgett Films
    (2020)
    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
    Design, Synthesis, and Self-Assembly Behavior of Liquid-Crystalline Bis-[60]Fullerodendrimers
    (2016)
    Russo, Virginie
    ;
    Pieper, Pauline
    ;
    Heinrich, Benoît
    ;
    Donnio, Bertrand
    ;
    Deschenaux, Robert 
    Bis-[60]fullerodendrimers were synthesized by assembling [60]fullerene-containing type I (terminal olefin) and type II (a,ß-unsaturated carbonyl olefin) olefins through the olefin cross-metathesis reaction. The synthetic modular approach developed in this study allowed the preparation of mono-[60]fullerodendrimers and their [60]fullerene-free analogues. First- and second-generation poly(aryl ester) dendrons carrying cyanobiphenyl mesogens were used as liquid-crystalline promoters. The liquid- crystalline properties were studied by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. In agreement with the nature and structure of the dendrimers, nematic, smectic, and multisegregated lamellar phases were observed. Owing to its versatility and tolerance towards many functional groups, olefin cross-metathesis proved to be a reaction of choice for the elaboration of molecular materials with complex architectures.
  • Publication
    Accès libre
    Piling Up Pillar[5]arenes To Self-Assemble Nanotubes
    (2016)
    Nierengarten, Iwona
    ;
    Guerra, Sebastiano 
    ;
    Ben Aziza, Haifa
    ;
    Holler, Michel
    ;
    Abidi, Rym
    ;
    Barberá, Joaquín
    ;
    Deschenaux, Robert 
    ;
    Nierengarten, Jean-François
    New liquid-crystalline pillar[5]arene derivatives have been prepared by grafting first- generation Percec-type poly(benzylether) dendrons onto the macrocyclic scaffold. The molecules adopt a disc-shaped structure perfectly suited for self-organization into a columnar liquid-crystalline phase. In this way, the pillar[5]arene cores are piled up, thus forming a nanotubular wire encased within a shell of peripheral dendrons. The capability of pillar[5]arenes to form inclusion complexes has been also exploited. Specifically, detailed binding studies have been carried out in solution with 1,6- dicyanohexane as the guest. Inclusion complexes have also been prepared in the solid state. Supramolecular organization into the Colh mesophase has been deduced from X-ray diffraction data and found to be similar to that observed within the crystal lattice of a model inclusion complex prepared from 1,4-dimethoxypillar[5]arene and 1,6- dicyanohexane.
  • Publication
    Accès libre
    NMR spectroscopy and DFT calculations of a self-assembled arene ruthenium rectangle obtained from a combination of coordination and hydrogen bonds
    (2016)
    Appavoo, Divambal
    ;
    Raja, Nandhagopal
    ;
    Deschenaux, Robert 
    ;
    Therrien, Bruno 
    ;
    Carnevale, Diego
    The hydrogen-bonded arene ruthenium metalla-rectangle, [(p-cymene) 2Ru2(OOnOO)(UPy)2]24+ , obtained from 1-(4-oxo-6-undecyl-1,4-dihydropyrimidin-2-yl)-3-(pyridin-4- ylmethyl)urea (UPy) and the dinuclear arene ruthenium clip (p-cymene) 2Ru2(OOnOO)Cl2 (OOnOO = 2,5-dioxido-1,4- benzoquinonato), is investigated by means of solution-phase NMR spectroscopy. Rotating frame nuclear Overhauser effect measurements are used to probe the H- bond network that drives the UPy self-assembly as well as the full rectangular supramolecular system. An effective distance that takes into account both intra-and intermolecular polarization-transfer pathways is utilised for data analysis. The experimental findings are corroborated by DFT calculations of NMR parameters and internuclear distances, thus confirming the formation of a very stable tetranuclear metalla-assembly.
  • Publication
    Accès libre
    Designing liquid-crystalline gold nanoparticles via the olefin cross-metathesis reaction
    (2016)
    Nguyen, Thanh Tung
    ;
    Nguyen, Thi Le Anh
    ;
    Deschenaux, Robert 
    Liquid-crystalline gold nanoparticles were prepared by grafting mesomorphic α,β- unsaturated carbonyl olefins onto the organic shell of gold nanoparticles containing terminal olefin ligands by applying the olefin cross-metathesis. The latter reaction was performed under standard conditions using second-generation Grubbs catalyst. The title materials were found to be stable up to 200 °C and gave rise to the formation of smectic A phases in agreement with the structure and nature of the liquid-crystalline promoters. The olefin cross-metathesis proved to be a reaction of choice for the design of liquid-crystalline nanoparticles.
  • Publication
    Accès libre
    Combining coordination and hydrogen-bonds to form arene ruthenium metalla-assemblies
    (2016)
    Appavoo, Divembal
    ;
    Carnevale, Diego
    ;
    Deschenaux, Robert 
    ;
    Therrien, Bruno 
    Three ureido-pyrimidone derivatives (N-LH) were used to generate in combination with four dinuclear arene ruthenium clips, (p-cymene) 2Ru2(OO boolean AND OO)Cl2 (OO boolean AND OO = oxalato, 2,5-dioxido-1,4-benzoquinonato, 2,5-dichloro-1,4-benzoquinonato, 5,8-dioxido-1,4-naphtoquinonato), twelve cationic arene ruthenium metalla-cycles of the general formula [(p-cymene)2Ru2(OO boolean AND OO)(N-LH)2]2 (CF3SO3)4. The ureidopyrimidone moieties are able to form strong hydrogen-bonds by self-pairing, thus giving rise to dimeric structures in solution. In addition, to better understand the behavior of the tetranuclear metallacycles in solution, the neutral dinuclear arene ruthenium ureido-pyrimidone complexes of the general formula ((p-cymene)RuCl2(N-LH)} 2 were also prepared and characterized. All metalla-assemblies were studied in solution by NMR spectroscopy, confirming the high stability of the metalla- cycles and the usefulness of hydrogen-bonds in constructing supramolecular assemblies
  • Publication
    Accès libre
    Liquid-Crystalline Dendrimers Designed by Click Chemistry
    (2016)
    Guerra, Sebastiano 
    ;
    Nguyen, Thi Le Anh
    ;
    Furrer, Julien
    ;
    Nierengarten, Jean-François
    ;
    Barberá, Joaquín
    ;
    Deschenaux, Robert 
    Liquid-crystalline dendrimers have been prepared from second-generation Percec- type poly(benzyl ether) dendrons or second-generation poly(aryl ester) dendrons carrying cyanobiphenyl mesogens. The Janus dendrimer, which combines the two types of dendromesogens, has also been synthesized. Those compounds have been prepared under copper-catalyzed azide–alkyne cycloaddition conditions. The mesomorphic properties have been studied by thermal analysis (POM, DSC) and small-angle X-ray scattering. Smectic A, nematic, and columnar phases have been observed depending on the dendritic building blocks. The click reaction has proven to be a powerful and elegant synthetic tool for the design of complex dendritic liquid- crystalline architectures.
  • Publication
    Accès libre
    Red and Blue Liquid-Crystalline Borondipyrromethene Dendrimers
    (2015)
    Mula, Soumyaditya
    ;
    Frein, Stéphane
    ;
    Russo, Virginie
    ;
    Ulrich, Gilles
    ;
    Ziessel, Raymond
    ;
    Barberá, Joaquín
    ;
    Deschenaux, Robert 
    We have designed a series of modular and fluorescent poly(arylester) dendrimers functionalized with cyanobiphenyl subunits and fluorescent borondipyrromethene (Bodipy) dyes. The green emitter is a Bodipy with four methyl groups, and the Bodipy dye possessing extended conjugation with two methyl and two vinyl groups acts as a red emitter. The design element of these architectures relates to a secondary amide linkers interposed between the conventional Bodipy and the dendrons. The second- and third-generation dendrimers give rise to nematic and/or smectic A phases, whereas the first-generation dendrimers show smectic A and C phases or an unidentified mesophase. The novel materials are highly fluorescent in solution and in the as-obtained powders but not in the mesophase. Dilution of the dendritic dyes with the nonfluorescent acid dendron in the solid phase shifted the fluorescence to higher energy, and demonstrated the presence of aggregates in the solid state. Mixing the red and blue materials in a solid phase led to the observation of effective electronic energy transfer from the red dye to the blue one. Increasing the proportion of the red dye (energy donor) from 1 to 250 molar with respect to the blue dye (energy acceptor) resulted in the observation of residual emission of the red dye in the solid state mixture. Increasing the proportion from 1 to 1000 resulted in equal emission in the 540 to 760 nm range.
  • Publication
    Accès libre
    Self-organisation of dodeca-dendronized fullerene into supramolecular discs and helical columns containing a nanowire-like core
    (2015)
    Guerra, Sebastiano 
    ;
    Iehl, Julien
    ;
    Holler, Michel
    ;
    Peterca, Mihai
    ;
    Wilson, Daniela A
    ;
    Partridge, Benjamin E
    ;
    Zhang, Shaodong
    ;
    Deschenaux, Robert 
    ;
    Nierengarten, Jean-Francois
    ;
    Percec, Virgil
    Twelve chiral and achiral self-assembling dendrons have been grafted onto a [60]fullerene hexa-adduct core by copper-catalyzed alkyne azide "click" cycloaddition. The structure adopted by these compounds was determined by the self-assembling peripheral dendrons. These twelve dendrons mediate the self-organisation of the dendronized [60]fullerene into a disc-shaped structure containing the [60]fullerene in the centre. The fullerene-containing discs self-organise into helical supramolecular columns with a fullerene nanowire-like core, forming a 2D columnar hexagonal periodic array. These unprecedented supramolecular structures and their assemblies are expected to provide new developments in chiral complex molecular systems and their application to organic electronics and solar cells.
  • Publication
    Accès libre
    Preparation of Pillar[5]arene-Based [2]Rotaxanes from Acyl Chlorides and Amines
    (2015)
    Milev, Radian
    ;
    Lopez-Pacheco, Alberto
    ;
    Nierengarten, Iwona
    ;
    Trinh, Thi Minh Nguyet
    ;
    Holler, Michel
    ;
    Deschenaux, Robert 
    ;
    Nierengarten, Jean-François
    Pillar[5]arene-based [2]rotaxanes have been prepared from the reactions of diacyl chloride reagents with various amine stoppers. The yields of the [2]rotaxanes are sensitive to the reaction conditions (solvent and stoichiometry) as well as to structural and electronic factors. In particular, the nature of the starting amine reagent has a dramatic influence on the yields of [2]rotaxanes; thus, the reaction outcome is not simply related to the binding constant of the diacyl chloride reagent with the pillar[5]arene. Indeed, the differences in the yields must be related to the different affinities for the various monoacylated intermediates. The yields of the [2]rotaxanes are also influenced by several structural factors such as the chain length of the diacyl chloride reagent and the size of the peripheral substituents of the pillar[5]arene building block. Finally, the preparation of [2]rotaxanes from alkyldiamine reagents and acyl chloride stoppers has also been investigated.