Helically chiral functionalized [6]helicene: Synthesis, optical resolution, and photophysical properties
Publication date: July 2018Source: Comptes Rendus Chimie, Volume 21, Issue 7Author(s): Nesrine Hafedh, Faouzi Aloui, Vincent Dorcet, Houcine BarhoumiAbstractA short and efficient synthetic pathway leading to a new chiral π-conjugated system is reported. The X-ray structure of the target compound was determined and showed a helical conformation. Its resolution was successfully accomplished, leading to two enantiomers in high optical purity, and their chiroptical properties were examined experimentally. The photophysical properties of the organic material were also evaluated, showing an emission in the visible region, and H...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
SiO2-functionalized melamine-pyridine group–supported Cu(OAc)2 as an efficient heterogeneous and recyclable nanocatalyst for the N-arylation of amines through Ullmann coupling reactions
This study reports a convenient approach to prepare SiO2/CCPy/Cu(OAc)2 as a novel nanocatalyst, in which melamine-bearing pyridine groups have functionalized SiO2 and can act as a capping agent to stabilize Cu(II) species. The catalyst is characterized through Fourier transform infrared, transmission electron microscopy, field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis, inductivity coupled plasma (ICP), and energy dispersive X-ray (EDX) techniques. Furthermore, its catalytic behavior is evaluated in the N-arylation of indole, imidazole, and aniline during Ull...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Theoretical study of Sn adsorbed on the MgO(100) surface with defects
In this study, the adsorption of Sn atom at various sites on the MgO(100) surface was characterized using a theoretical approach based on density functional theory calculations. Both regular adsorption centers (O2− and Mg2+) and defects (such as neutral and charged O and Mg vacancies) were considered. Several key parameters for these sites with the adsorbed Sn atom were determined to provide its geometric, energetic, and electronic characterization. The interaction between Sn and the Mg vacancy sites is very strong and is associated with a relatively small distance of the adsorbed Sn atom from the surface and with a larg...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Comparative assessment of the ability of a microwave absorber nanocatalyst in the microwave-assisted biodiesel production process
In this study, a carbon-supported KOH/Ca12Al14O33 nanocomposite was fabricated via the microwave combustion method, in which dextrose was used as a carbon source, and its activity in the microwave-assisted transesterification reaction as a microwave absorption material was assessed. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry, Brunauer–Emmett–Teller (BET), field-emission scanning electron microscopy, and energy dispersive X-ray analyses. The results showed that the carbonate and noncarbonate samples had a calcium aluminate (Ca12Al14O33) structure as a s...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Magnetic recyclable eggshell-based mesoporous catalyst for biodiesel production from crude neem oil: Process optimization by central composite design and artificial neural network
Publication date: July 2018Source: Comptes Rendus Chimie, Volume 21, Issue 7Author(s): Adewale S. Oladipo, Olusegun A. Ajayi, Akeem A. Oladipo, Solmaz L. Azarmi, Yusuf Nurudeen, Abdulazeez Y. Atta, Shola S. OgunyemiAbstractA magnetically recyclable eggshell-based catalyst (MKEC) was synthesized to circumvent saponification during the conversion of neem, Jatropha, and waste cooking oils (free fatty acid, 2.3–6.6%) to biodiesel. The characterization results indicated that MKEC had a mesoporous structure with the pore width of 3.24 nm, a specific surface area of 128 m2/g, and a pore volume of 0.045 cm3/g. The results con...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Editorial Board - English
Publication date: July 2018Source: Comptes Rendus Chimie, Volume 21, Issue 7Author(s): (Source: Comptes Rendus Chimie)
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Synthesis and optical and electrochemical properties of polycyclic aromatic compounds based on bis(benzothiophene)-fused fluorene
Publication date: Available online 4 July 2018Source: Comptes Rendus ChimieAuthor(s): Guiting Chen, Xin Li, Ziyun Chen, Chunbao Tang, Wei Yang, Yong CaoAbstractNovel polycyclic aromatic compounds (FBTPhO3 and FBTPhO4), which are based on bis(benzothiophene)-fused fluorene functionalized with oligo(ethylene glycol)-substituted phenyl, were synthesized through an intramolecular electrophilic cyclizing reaction. Thermal measurements revealed their excellent thermal stability and amorphous state. Photoluminescence spectra suggested that they both show deep blue light emission. Cyclic voltammetry tests exhibited that the ioniza...
Source: Comptes Rendus Chimie - July 5, 2018 Category: Chemistry Source Type: research
Synthesis and optical and electrochemical properties of polycyclic aromatic compounds based on bis(benzothiophene)-fused fluorene
Publication date: Available online 4 July 2018 Source:Comptes Rendus Chimie Author(s): Guiting Chen, Xin Li, Ziyun Chen, Chunbao Tang, Wei Yang, Yong Cao Novel polycyclic aromatic compounds (FBTPhO3 and FBTPhO4), which are based on bis(benzothiophene)-fused fluorene functionalized with oligo(ethylene glycol)-substituted phenyl, were synthesized through an intramolecular electrophilic cyclizing reaction. Thermal measurements revealed their excellent thermal stability and amorphous state. Photoluminescence spectra suggested that they both show deep blue light emission. Cyclic voltammetry tests exhibited that the ioni...
Source: Comptes Rendus Chimie - July 4, 2018 Category: Chemistry Source Type: research
R éaction pseudo-multicomposants entre le glutaconate de diméthyle et des aldéhydes aromatiques induite par le bromure de phénylzinc : accès domino à des dihydropyranones 2,3,5-trisubstituées
Publication date: Available online 28 June 2018 Source:Comptes Rendus Chimie Author(s): Erwan Le Gall, Marc Presset, Éric Léonel, Pascal Retailleau Phenylzinc bromide enables a pseudo three-component reaction of methyl glutaconate and aromatic aldehydes. Unsaturated trisubstituted δ-valerolactones (dihydropyranones) are obtained in fair to good yields by an aldol/aldol/elimination/lactonization domino process that allows the formation of four new bonds in a single step. A putative reaction mechanism is proposed. Graphical abstract (Source: Comptes Rendus Chimie)
Source: Comptes Rendus Chimie - June 29, 2018 Category: Chemistry Source Type: research
Surface reactivity of uranium hexafluoride (UF6)
Publication date: Available online 23 June 2018 Source:Comptes Rendus Chimie Author(s): Bertrand Morel, Ania Selmi, Laurent Moch, Jean-Michel Hiltbrunner, Mickael Achour, Rachid Benzouaa, Aurélien Bock, Laurent Jouffret, Pierre Bonnet, André Hamwi, Marc Dubois The present article reviews a selection of results obtained in the AREVA/CNRS/UCA joint research laboratory. It focuses on interfaces formed by uranium hexafluoride (UF6) with chemical filter (purification), carbon (UF6 storage), and metallic substrate (corrosion). As a matter of fact, along the nuclear fuel cycle, metallic surfaces of the fluorination...
Source: Comptes Rendus Chimie - June 24, 2018 Category: Chemistry Source Type: research
Hexavalent chromium quantification in solution: Comparing direct UV –visible spectrometry with 1,5-diphenylcarbazide colorimetry
Publication date: Available online 22 June 2018 Source:Comptes Rendus Chimie Author(s): Arnaud Sanchez-Hachair, Annette Hofmann Quantification of Cr(VI) in an aqueous solution is conducted by direct UV–visible spectrophotometry based on the yellow coloring of the chromate ion. Measurements show that absorption follows the Beer–Lambert law over a wide range of concentrations. At pH below the pK a of 6.4 (HCrO4 −/CrO4 −2), the absorption maximum lies at 350 nm wavelength and the linear range spans from 0.5 to 100 mg Cr(VI)/L; above the pK a (pH 6.4), the absorption maximum is 373 nm and linearity occurs in the...
Source: Comptes Rendus Chimie - June 22, 2018 Category: Chemistry Source Type: research
Nanostructured ternary composites of PPy/CNT/NiFe2O4 and PPy/CNT/CoFe2O4: Delineating and improving microwave absorption
Publication date: Available online 19 June 2018 Source:Comptes Rendus Chimie Author(s): Erfan Ghashghaei, Somayyeh Kheirjou, Sara Asgari, Hanif Kazerooni Two different ternary nanocomposites, PPy/CNT/CoFe2O4 and PPy/CNT/NiFe2O4, were synthesized by in situ polymerization method. The resulting composites were characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. They were evaluated with the aim of investigating microwave absorption properties. The results showed that the value of microwave refl...
Source: Comptes Rendus Chimie - June 20, 2018 Category: Chemistry Source Type: research
Imidazolinone and triazine herbicides in soils in relation to the complexes formed with Cu(II) ions
In conclusion, crops treated with such herbicides in conjunction with Cu(II) salts experience a decrease in its persistence and effectiveness. In addition, the herbicides and the copper ions may pass to the phreatic layer of the soil, increasing the chance of pollution. Graphical abstract (Source: Comptes Rendus Chimie)
Source: Comptes Rendus Chimie - June 19, 2018 Category: Chemistry Source Type: research
Microscopic models of spin crossover
Publication date: Available online 15 June 2018 Source:Comptes Rendus Chimie Author(s): Ján Pavlik, Jorge Linares The basic model for thermal spin crossover (SCO) is discussed in its microscopic and thermodynamic formulation. Compared to the basic model, its more elaborated forms formulated in course of almost 50 years are briefly reviewed with emphasis on their additional features. A separate section is devoted to the newer developments in the field of modelling of the SCO nanoparticles. The presentation of models is led in a comparative way to provide an accessible outline of the foundations of modern theoretical re...
Source: Comptes Rendus Chimie - June 15, 2018 Category: Chemistry Source Type: research
The power of synthesis towards new materials
Publication date: Available online 14 June 2018 Source:Comptes Rendus Chimie Author(s): Michael Veith, Pierre Braunstein (Source: Comptes Rendus Chimie)
Source: Comptes Rendus Chimie - June 14, 2018 Category: Chemistry Source Type: research
