M. F. Achard’s research while affiliated with French National Centre for Scientific Research and other places

Composite PVA/ZnO-nanorods fibers, synthesized through co-axial flux extrusion exhibit higher anisotropic photonic properties, both in absorption and emission, as a result of the collective alignment of the ZnO nanorods along the main axis of the PVA fiber. This photonic anisotropy is triggered by a synergistic interaction between the PVA matrix, stretched above the glass transition temperature (Tg), and cooled down under strain. Compared with non-elongated fibers that present an isotropic emission, composite fibers previously submitted to a tensile stress absorb selectively UV emission when the polarized laser beam is parallel to the main axis of the fiber. In addition, their photolumincescence is also anisotropic, with a waveguide behavior along the main axis of the fiber. Mechanical properties of these composite fibers are also drastically improved, compared with pure PVA fibers: the longitudinal Young modulus of these fibers is increased from 2 to 6 GPa upon ZnO addition, a value similar to those already observed for composite fibers, prepared either with carbon nanotubes, or V2O5 macroscopic fibers.

Atropoisomeric aromatic cores enhance disorder inside the supramolecular packing of disk-shaped mesogens. Core-extension of perylene with an atropoisomeric [4]helicene fragment thus gives rise to a room-temperature liquid crystal even with nearly no flexible side chains. Replacement of diester moieties by imide substituents allows switching from donor- to acceptor-type electronic characteristics.

Several series of unidimensional coordination polymers of formula [Zn(C(n)H(2n+1)trz)(3)](Cl)(2)·xH(2)O (n = 18, 16, 13, 11, 10, trz = 4-substituted-1,2,4-triazole), [Zn(C(18)H(37)trz)(3)](ptol)(2)·xH(2)O, [Fe(C(n)H(2n+1)trz)(3)](X)(2)·xH(2)O (n = 18, 16, 13, 10; X = Cl(-) or ptol(-), where ptol(-) = p-tolylsulfonate anion), and [Fe(C(18)H(37)trz)(3)](X)(2)·xH(2)O (X = C(8)H(17)PhSO(3)(-) and C(8)H(17)SO(3)(-)) are reported with their thermal, structural, and magnetic properties. Most of these materials exhibit thermotropic lamellar mesophases at temperatures as low as 410 K, as confirmed by textures observed by polarized optical microscopy. The corresponding phase diagrams deduced by differential scanning calorimetry are also reported. All iron-containing materials present a spin crossover phenomenon that occurs at temperatures ranging from 242 to 360 K, only slightly below the mesophase temperature domain, and remains complete and cooperative, even for the longer alkyl substituents. The use of stable diamagnetic Zn(II) analogues proves to be very useful to characterize the comparatively less stable and less crystalline Fe(II) analogues.

Porous carbon foams were prepared by pyrolysis of phenolic resin from a dual-template approach using silica monoliths as hard templates and triblock copolymers as soft templating agents. Macroporosity of 50–80% arose from the Si(HIPE) hard template (the acronym “HIPE” refers to the high internal phase emulsion process), while the soft template generated micro- or mesoporosity, according to the operating procedure. The final materials exhibited a Brunauer–Emmett–Teller specific surface area of 600–900 m2·g–1. Their performances as electrodes for electrochemical capacitors or Li ion battery negative electrodes were investigated. The mesoporous foams gave the best capacitance, up to 20 F·g–1. In battery configuration, the microporous foams delivered an irreversible capacity of 500–600 mA·h·g–1 during the first discharge. Upon charging, partial extraction of Li gave reversible capacities of 125–150 mA·h·g–1.

Unter Kontrolle: Die Organisation eines thermotropen Flüssigkristalls kann zur Kontrolle des Wachstums anorganischer Nano-Objekte (wie ZnO) genutzt werden. Liegen die Systeme in ihrer nematischen Phase vor, so bilden sich anisotrope Nanopartikel, während unter isotropen Bedingungen isotrope Nanopartikel entstehen. Das Spiel mit der exakten Natur der Flüssigkristalle ermöglicht die Kontrolle der Größe und des Längenverhältnisses der Nanopartikel (siehe Bild).

The one-pot synthesis and use of monolithic biohybrid foams in a continuous flow device reported in here presents the advantages of covalent stabilization of the enzymes, together with a low steric hindrance between proteins and substrates, optimized mass transport due to the interconnected macroporous network and simplicity with regard to the column in situ synthetic path. Those features, when applied to transesterification (biodiesel production) via enzyme catalysis, provide among the top enzymatic activities displayed by biohybrid catalysts bearing unprecedented endurance of continuous catalysis for a two month period.

Benzo[ghi]perylene 1,2,4,5,10,11-hexacarboxylic trialkylimide and dialkylimido-dialkyl ester derivatives, displaying a thermodynamically stable hexagonal columnar liquid-crystalline phase at room temperature, have been obtained by the use of previously unexplored chiral racemic α-branched alkylimide functions. One of the trialkylimides described here is the first room temperature columnar solely oligo-alkylimide-substituted arene, and thus constitutes a prototype case of self-assembling organic acceptor materials. As the related hexacarboxylic hexaesters are found to exhibit only a weak tendency to form columnar mesophases, benzo[ghi]perylene 1,2,5,10-tetracarboxylic tetraalkyl esters have been synthesized by regioselective oxidative Diels-Alder addition of maleic anhydride to 3,10-dicyanoperylene, and a room temperature hexagonal columnar mesophase was obtained with branched alkyl chains. The acceptor-type electronic properties of the tri- and diimides have been found to be considerably more pronounced than those of the hexa- and tetracarboxylic esters, and to approach those of the prototype acceptor material C(60). The formation of bathochromically absorbing donor-acceptor complexes was observed with a di- or triimide as acceptor and a tetraester as donor, but not with a hexaester as donor. Exploiting the non-negligible differences in reduction and oxidation potentials between all four types of materials, the minimum HOMO energy difference necessary for charge-transfer-complex formation has been determined to lie between 0.29 and 0.35 eV.

Upon extrusion process, first vanadium oxide macroscopic fibers have been obtained. They are associated to longitudinal Young modulus from 15 to 25 GPa and depict strong high scale textural anisotropy as observed through cross-polarized microscopy. TEM observations and SAXS experiments reveal that those macroscopic fibers are made of nanoscopic ribbons associated to preferential orientation parallel to the macroscopic fiber main axis, while XRD and NMR investigations reveal a microstructure close to the V2O5.1.8H2O xerogels. These fibers can detect down to 0.1 ppm of ethanol within 16 seconds at 40°C.

Palladium nanoparticles supported within hybrid organic–inorganic foams have been generated. The as-synthesized catalysts, labeled “Pd@gOrgano-Si(HIPE)” (high internal phase emulsion), have been tested with or without addition of triphenylphosphine (PPh3), considering both the Suzuki–Miyaura and Mizoroki–Heck coupling reactions. Particularly, the catalysts Pd@gMercapto-Si(HIPE)-P4 and Pd@g3Amino-Si(HIPE)-P4 under addition of (PPh3) in a molar ratio 4:1 relative to palladium, are offering good yields, turnover and cycling performances for the Mizoroki–Heck coupling reaction.

Integrative chemistry-based rational design has been used to synthesize the first lipase [C-CRl]@Glymo-Si(HIPE) and [C-TAl]@Glymo-Si(HIPE) hybrid macrocellular biocatalysts, where immobilization of crude enzymes is optimized, while circumventing the reactants' low kinetic diffusion, by the use of silica macroporous hosts. As a direct consequence, these new hybrid biocatalysts display unprecedented cycling catalysis performance, as demonstrated by the syntheses of butyloleate ester (used as biodiesel lubricant), hydrolysis of linoleic-glycero ester derivatives (end products used for detergent and soap generations), and trans-esterification (reaction involved in the synthesis of low viscosity biodiesel). Considering that the catalytic performances are given in terms of absolute conversion percentage and not just relative enzyme activity, the enzyme@Glymo-Si(HIPE) hybrid macrocellular biocatalysts presented in this study display unprecedented high yield cycling catalysis performances, where turnover numbers (TON) and turnover frequencies (TOF) show promise for real industrial applications. This study can be considered as a milestone for enzyme-based heterogeneous catalyzes, thereby enhancing their competitiveness with the supported-catalysts commonly used in industry, in total agreement with current sustainable development issues. Also, the new macrocellular biocatalysts are well-suited for large-scale industrial production because of their above-mentioned performance characteristics, further enhanced by their monolithic character, which eases the separation of the catalysts from other reaction components.