| 1. |
- Bouligand, Yves, et al.
(författare)
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Blue-phase drops on a glass interface and their decoration at the cholesteric transition
- 2008
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Ingår i: Comptes Rendus Chimie. - : Elsevier BV. - 1631-0748. ; 11:3, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- Free-surface drops of blue phase attached to a glass slide present topologically concentric lines, which we first believed to be steps at the air interface, as this was often observed in smectic drops or in other liquid crystals. Actually these contours lie at the glass interface, or in its close vicinity, but do not really form steps. While the existence of steps at the air interface cannot be excluded, we did not observe them in this study. Reproducible decorations were observed at the transition from the blue phase to the cholesteric liquid crystal, and showed a geometry close to that found in certain biological structures, which may be considered as stabilized analogues of blue phases.
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| 2. |
- Bruschi, Maurizio, et al.
(författare)
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A DFT investigation on structural and redox properties of a synthetic Fe6S6 assembly closely related to the [FeFe]-hydrogenases active site
- 2008
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Ingår i: Comptes Rendus. Chimie. - : Elsevier BV. - 1631-0748. ; 11:8, s. 834-841
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Tidskriftsartikel (refereegranskat)abstract
- In the present contribution, a density functional theory (DFT) investigation is described regarding a recently synthesized Fe6S6 complex - see C. Tard, X. Liu, S.K. Ibrahim, M. Bruschi, L. De Gioia, S.C. Davies, X. Yang, L.-S. Wang, G. Sawers, C.J. Pickett, Nature 433 (2005) 610 - that is structurally and functionally related to the [FeFe]-hydrogenases active site (the so-called H-cluster, which includes a binuclear subsite directly involved in catalysis and an Fe4S4 cubane). The analysis of relative stabilities and atomic charges of different isomers evidenced that the structural and redox properties of the synthetic assembly are significantly different from those of the enzyme active site. A comparison between the hexanuclear cluster and simpler synthetic diiron models is also described; the results of such a comparison indicated that the cubane moiety can favour the stabilization of the cluster in a structure closely resembling the H-cluster geometry when the synthetic Fe6S6 complex is in its dianionic state. However, the opposite effect is observed when the synthetic cluster is in its monoanionic form.
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| 3. |
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| 4. |
- Flemström, Andreas, et al.
(författare)
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Inheritance of guanidinium chloride structure in two Molybdenum(II) chloride salts
- 2005
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Ingår i: Comptes rendus. Chimie. - : Elsevier SAS. - 1631-0748 .- 1878-1543. ; 8:11-12, s. 1750-1759
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Tidskriftsartikel (refereegranskat)abstract
- Depending on the proticity of the solvent, two different salts may be crystallized from the combination of solutions of guanidinium chloride, C(NH2)3Cl, and the acidic hydrate of molybdenum dichloride, [(Mo6Cl8)Cl6](H20O9). From aprotic solvents such as dimethyl sulfoxide (DMSO) or formamide (FA), compound I, [(Mo6Cl8)Cl6]Cl6(C(NH2)3)8, crystallizes, while from protic solvents such as ethanol or water, compound II, [(Mo6Cl8)Cl6]Cl3(C(NH2)3)5, crystallises. In both compounds, the basic motif of the two parent structures, the octahedral [(Mo6Cl8)Cl6]2– cluster and the planar, triangular, C(NH2)3Cl3 entity are fairly well preserved. The assembly of the blocks, however, differs distinctly, and while both compounds are rather porous, compound I (s.g. Fm m, No. 225) has a volume of 27 Å3/non-hydrogen atom, compound II (s.g. C2/c, No. 15) is somewhat denser, with a volume of 24 Å3/non-hydrogen atom.
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| 5. |
- François, Camille, et al.
(författare)
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Design and synthesis of biobased epoxy thermosets from biorenewable resources
- 2017
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Ingår i: Comptes rendus. Chimie. - : Elsevier BV. - 1631-0748 .- 1878-1543. ; 20:11-12, s. 1006-1016
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Tidskriftsartikel (refereegranskat)abstract
- Biobased diepoxy synthons derived from isoeugenol, eugenol or resorcinol (DGE-isoEu, DGE-Eu and DGER, respectively) have been used as epoxy monomers in replacement of the diglycidyl ether of bisphenol A (DGEBA). Their curing with six different biobased anhydride hardeners leads to fully biobased epoxy thermosets. These materials exhibit interesting thermal and mechanical properties comparable to those obtained with conventional petrosourced DGEBA-based epoxy resins cured in similar conditions. In particular, a high T-g in the range of 90-130 degrees C and instantaneous moduli higher than 4.3 GPa have been recorded. These good performances are very encouraging, making these new fully biobased epoxy thermosets compatible with the usual structural application of epoxy materials.
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| 6. |
- Gao, Weiming, et al.
(författare)
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An azadithiolate bridged Fe2S2 complex as active site model of FeFe-hydrogenase covalently linked to a Re(CO)(3)(bpy)(py) photosensitizer aiming for light-driven hydrogen production
- 2008
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Ingår i: Comptes rendus. Chimie. - : Elsevier BV. - 1631-0748 .- 1878-1543. ; 11:8, s. 915-921
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Tidskriftsartikel (refereegranskat)abstract
- In order to create photoactive catalysts for hydrogen production, a novel trimetallic Re-Fe2S2 complex 4 was synthesized by the coordination of the free -PPh2 group of the ligand of the rhenium photosensitizer 6 to an azadithiolate (ADT)-bridged diiron complex 8 with the assistance of the decarbonylation reagent Me3NO. Complex 4 was characterized by H-1, C-13, P-31 NMR and HRMS spectra. The IR, UV-vis and electrochemical data indicate some interactions between Re and Fe2S2 moieties, and the photo-induced electron transfer from the excited state of the Re moiety to the Fe2S2 catalyst is thermodynamically feasible.
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| 7. |
- Hashemzehi, Mojgan, et al.
(författare)
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A study on the structure and catalytic performance of ZnxCu1-xAl2O4 catalysts synthesized by the solution combustion method for the esterification reaction
- 2016
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Ingår i: Comptes rendus. Chimie. - : Elsevier. - 1631-0748 .- 1878-1543. ; 19:8, s. 955-962
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Tidskriftsartikel (refereegranskat)abstract
- A ZnxCu1-xAl2O4 catalyst was prepared via the microwave-assisted solution combustion method (MSC). This method presents a fast procedure for industrial scale catalyst preparation. The physicochemical properties of the fabricated catalyst were characterized using XRD, FTIR, BET, SEM and TEM analyses. The catalytic performance through the esterification reaction was examined under the following conditions: reaction temperature = 180 degrees C, catalyst concentration = 3% (w/w), molar ratio of oleic acid to methanol = 9 and reaction time = 6 h. XRD results showed that loading both zinc and copper oxides on alumina at a ratio of amounts that were nearly the same resulted in decreased crystalline size and well-dispersed copper-alumina and zinc-alumina crystals. Moreover, the mean pore diameter of the sample was increased by simultaneous loading of zinc and copper oxides on alumina that enhanced permeation of the reactants within pores and increased the interaction of the reactant with the catalyst active sites. The catalyst showed minimum tendency towards adsorbing moisture from air, which was attributed to it having less atoms on the surface through which binding with H2O molecules takes place. The highest level of activity in the esterification reaction (96.9%) was obtained at the optimum ratio of the Zn:Cu molar ratio, identified to be 2:3. The sample particles ranged from 10 to 30 nm in size, without agglomeration. (C) 2016 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
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| 8. |
- Jarenmark, Martin, et al.
(författare)
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Asymmetric dinuclear metal complexes as models for active sites in hydrolases and redox enzymes
- 2007
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Ingår i: Comptes Rendus. Chimie. - : Elsevier BV. - 1631-0748. ; 10:4-5, s. 433-462
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Forskningsöversikt (refereegranskat)abstract
- Recent advances in the synthesis of biomimetic asym. dinuclear transition metal complexes are reviewed. Emphasis is put on description of asym. model complexes for the active sites of the enzymes purple acid phosphatase, zinc phosphotriesterase, urease, Cu, Zn superoxide dismutase, tyrosinase, and catechol oxidase.
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| 9. |
- Karlsson, Ola, et al.
(författare)
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The effect of first-stage polymer Tg on the morphology and thermomechanical properties of structured polymer latex particles
- 2003
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Ingår i: Comptes Rendus. Chimie. - : Elsevier BV. - 1631-0748. ; 6:11-12, s. 1233-1244
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Tidskriftsartikel (refereegranskat)abstract
- A series of heterogeneous latexes having stage ratios of 40:60 between the first and second stage polymers were prepared by emulsion polymerization. The first-stage polymers were non-polar S-BuA with Tgs ranging from + 100 °C to + 20 °C and the second stage polymer was polar MMA–BuA–MAA having a Tg of 20 °C. The latex particle morphologies were studied using TEM and the thermomechanical properties of the resulting latex films were studied with DSC and DMA. Calculated diffusion rates for propagating species during the reactions were correlated to the observed morphologies and to the amount of interphase in the latex particles.
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| 10. |
- Lindman, Björn, et al.
(författare)
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Nonionic polymers and surfactants: Temperature anomalies revisited
- 2009
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Ingår i: Comptes Rendus. Chimie. - : Elsevier BV. - 1631-0748. ; 12:1-2, s. 121-128
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Tidskriftsartikel (refereegranskat)abstract
- In view of a rapidly increasing importance in applications, as well as significant fundamental observations, the temperature anomalies displayed by several oxyethylene compounds, including poly(ethylene glycol), and oxyethylene surfactants and copolymers continue to create interest but also controversies. Here we review a wide range of experimental observations and present the different theoretical approaches that have been suggested. We find that a model that attributes the temperature effects to conformational changes that make the oxyethylene groups less polar at higher temperature has a strong predictive power and gives a quantitative rationalization of phase diagrams and other observations. In line with observations, it also predicts that the behaviour is not restricted to aqueous solutions but also occurs in other solvents. Different NMR approaches as well as Raman spectroscopy directly demonstrate the conformational behaviour predicted. We also note that the relevant molecular segment also occurs in other compounds, like cellulose derivatives such as methylcellulose. In line with this, qualitatively the same type of temperature anomalies is found for these compounds as with oxyethylene-containing substances. To cite this article: Bjo: Lindman, G. Karlstrom, C R. Chimie 12 (2009). (C) 2008 Academie des sciences. Published by Elsevier Masson SAS. All fights reserved.
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