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991.
Joanna KWICZAK-YTBAI 《Turkish Journal of Chemistry》2020,44(6):1515
Due to environmental concerns, increasing attention has been focused on the application and preparation of biobased polymers and their blends. In this study, cellulose, the most spread biopolymer on Earth, was used in the preparation of novel cotton/polypropylene-Au and cotton/polyethylene-Au nanocomposites via a green mechanochemical approach. First, mechanoradicals were generated by ball milling of the cotton and thermoplastics under cryo conditions, and then, these radicals were used in the reduction of Au ions to Au nanoparticles (Au NPs). Nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The application of mechanochemistry in obtaining the cotton/thermoplastic blends allowed homogenous and fine blending of the samples and in addition, excluded the usage of toxic solvents. Since Au NPs exhibit a wide range of applications, e.g., in catalysis, cotton/thermoplastic-Au nanocomposites were used to catalyze the reduction reaction of 4-nitrophenol to
4-aminophenol, followed by UV-Vis spectroscopy. Finally, the hydrophobicity of the nanocomposites was alternated by tuning the blend composition. In the prepared nanocomposites, cotton and thermoplastics acted as very good supporting matrices for the Au NPs and provided satisfactory access to the NPs. 相似文献
4-aminophenol, followed by UV-Vis spectroscopy. Finally, the hydrophobicity of the nanocomposites was alternated by tuning the blend composition. In the prepared nanocomposites, cotton and thermoplastics acted as very good supporting matrices for the Au NPs and provided satisfactory access to the NPs. 相似文献
992.
993.
Marcin A. Majewski Yongseok Hong Prof. Tadeusz Lis Dr. Janusz Gregoliński Prof. Piotr J. Chmielewski Dr. Joanna Cybińska Prof. Dongho Kim Prof. Marcin Stępień 《Angewandte Chemie (International ed. in English)》2016,55(45):14072-14076
Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold‐in method. This new hydrocarbon macrocycle contains a large 24‐membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π‐conjugated surface. The consequences of distortion in octulene were explored using photophysical methods, which revealed a reduced electronic band gap and greater flexibility of the π system. Octulene contains a functional cavity with a diameter larger than 5.5 Å that is capable of efficiently binding the chloride anion in a nonpolar solvent (Ka= 2.2(4)×104 m ?1, 1 % dichloromethane (DCM) in benzene). The octulene–chloride interaction is stabilized by eight weak C(sp2)H???Cl bonds, providing the first example of a hydrocarbon‐based anion receptor. 相似文献
994.
Enantiopure Sulfinyl Aniline as a Removable and Recyclable Chiral Auxiliary for Asymmetric C(sp3)−H Bond Activation 下载免费PDF全文
Soufyan Jerhaoui Dr. Faouzi Chahdoura Clémence Rose Dr. Jean‐Pierre Djukic Dr. Joanna Wencel‐Delord Prof. Françoise Colobert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17397-17406
An original and recyclable chiral bidentate aniline‐sulfoxide‐based directing group has been developed. This auxiliary allows challenging stereoselective Pd‐catalyzed direct functionalization of small cycloalkanes through C–aryl and C–alkyl bond formation. Although moderate diastereoselectivities are observed, both optically pure enantiomers of the highly functionalized products can be obtained separately by simple silica gel chromatography and cleavage of the chiral auxiliary. This strategy was further applied to the preparation of enantiomerically pure 1,2,3‐trisubstituted cyclopropane carboxylic acid derivatives, with three stereogenic centers and bearing both alkyl and aromatic substituents. These molecular scaffolds are not yet reported in the literature. The synthetic utility of this approach is validated by the chiral auxiliary being readily cleaved and recovered posteriori to the C?H activation step, without deterioration of its optical purity. Finally, an unprecedented palladacycle intermediate generated through C?H activation of the cyclopropane moiety has been isolated and fully characterized. Initial DFT calculations shed additional light on the reactivity of this original intermediate. 相似文献
995.
Joanna Prazmowska Tomasz Piasecki Adam Szyszka Regina Paszkiewicz Marek Tłaczała 《Central European Journal of Physics》2011,9(2):392-397
In the paper results of investigation of the influence of low concentration hydrogen on stress changes in thin catalytic metal
films were discussed. The concentration of H2 was altered from 6 ppm to 1% of hydrogen (6N) in nitrogen (6N). Silicon beams covered with palladium or platinum films of
various thicknesses were anchored at one end and their deflection at the other end was measured by atomic force microscope.
Stress changes were determined by application of modified Stoney formula and compared with results of computer modelling.
The influence of stress caused by hydrogen absorption on the alteration of output characteristics of AIII-N based hydrogen
sensors was excluded. The time dependence of stress in metallic films for various hydrogen concentrations indicated dissociation
limited mechanism of hydrogen absorption. 相似文献
996.
997.
Dr. Milan R. Milovanović Dr. Quentin Dherbassy Dr. Joanna Wencel-Delord Prof. Dr. Françoise Colobert Prof. Dr. Snežana D. Zarić Dr. Jean-Pierre Djukic 《Chemphyschem》2020,21(18):2136-2142
To figure out the possible role of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) as well as to provide reference thermochemical data in solution, the formation of Lewis acid-base complexes between HFIP (Lewis acid) and a series of 8 different Lewis bases (3 sulfoxides, 3 Nsp2 pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) was examined by isothermal titration calorimetry (ITC) experiments and static density functional theory augmented with Dispersion (DFT−D) calculations. Measured ITC association enthalpy values (ΔHa) lie between −9.3 and −14 kcal mol−1. Computations including a PCM implicit solvation model produced similar exothermicity of association of all studied systems compared to the ITC data with ΔHa values ranging from −8.5 to −12.7 kcal mol−1. An additional set of calculations combining implicit and explicit solvation by chlorobenzene of the reactants, pointed out the relatively low interference of the solvent with the HFIP-base complexation: its main effect is to slightly enhance the Gibbs energy of the HFIP-Lewis base association. It is speculated that the interactions of bulk HFIP with Lewis bases therefore may significantly intervene in catalytic processes not only via the dynamic microstructuring of the medium but also more explicitly by affecting bonds’ polarization at the Lewis bases. 相似文献
998.
999.
1000.
Theranostics: Polymer Capsules as a Theranostic Tool for a Universal In Vitro Screening Assay—The Case of Lysosomal Storage Diseases (Part. Part. Syst. Charact. 11/2015) 下载免费PDF全文