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Samira Karoune Hanen Falleh Mohamed Seif Allah Kechebar Youcef Halis Khaoula Mkadmini Mohamed Belhamra 《Natural product research》2015,29(5):452-454
This study compared phenolic contents and antioxidant activity in different organs of Acacia albida (leaves and bark) and focuses on identification of phenolic compounds of leaves by HPLC-DAD. The analysed organs exhibited differences in total polyphenol contents (100 and 59.5 mg GAE g? 1 DW). Phenolic contents of leaves were two times higher than those in bark. Ethanolic extracts exhibited good antioxidant activities with IC50 = 26 μg mL? 1 for DPPH and EC50 = 50 μg mL? 1 for FRAP. Identification by HPLC-DAD revealed the presence of nine phenolic compounds known for their high antioxidant activity. The results suggested that this species can be used as source of natural antioxidants. 相似文献
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J. Bennaceur R. Mechiakh F. Bousbih M. Jaouadi R. Chtourou 《Journal of Sol-Gel Science and Technology》2012,61(1):69-76
Titanium dioxide doped with iron (III) was prepared by sol–gel Spin Coating method. The phase structures, morphologies, particle
size of the doped TiO2 have been characterized by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and ultraviolet–visible
(UV–Vis) spectrophotometer. The XRD and Raman results show that the 10% Fe3+-doped TiO2 thin films crystallize in anatase phase between 600 and 800 °C, and into the anatase–rutile phase at 1,000 °C, and further
into the rutile phase when the content of Fe3+ increases (20%). The grain size calculated from XRD patterns shows that the crystallinity of the obtained anatase particles
increased from 39.4 to 43.4 nm as the temperature of annealing increase, whereas the size of rutile crystallites increases,
with increasing Fe3+ concentrations from 36.9 to 38.1 nm. The AFM surface morphology results confirmed that the particle size increases by increasing
the annealing temperature and also with an increasing of Fe3+ content. The optical band gap (E
g) of the films was determined by the UV–Vis spectrophotometer. We have found that the optical band gap decreased with an increasing
of annealing temperatures and also with an increasing of Fe3+ content. 相似文献
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K. Jaouadi N. Zouari T. Mhiri A. Daoud F. Romain 《Journal of Raman spectroscopy : JRS》2007,38(3):344-348
Raman spectra (10–1200 cm−1) of polycrystalline samples of Rb2(HSeO4)(H2PO4) were studied at temperatures ranging from 300 to 423 K. An assignment of most of the observed bands is proposed. The first‐order phase transition previously detected at 382 K was characterized as: This superionic‐protonic transition is believed to be governed by librations of the HSe/PO42− ion and the A OH (A = Se, P) stretching mode. It corresponds to the weakening of Se(P) O H˙˙˙ H O Se(P) hydrogen bonds and to the melting of the proton sublattice into a quasi‐liquid state in which the protons and the HSe/PO42− ions contribute to the unusually high conductivity. The activation energy that was determined from the plot Δν1/2 versus temperature for the ν (A OH) band has the same order of magnitude as that determined from conductivity measurements. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Synthesis, a complete structural characterization by X-ray diffraction, IR-Raman, and conductivity investigation are given for cesium–bismuth polyphosphate CsBi(PO3)4. This compound crystallizes in the monoclinic system with a space group P21/n (structural type IV). The structure consists of a three-dimensional framework made up of spiral (PO3)n chains linked by BiO8 polyhedra. Two infinite (PO3)n chains with a period of eight tetrahedra run along the [101] direction. The infrared and the Raman spectra show clearly some characteristic bands of infinite chain structures of PO4 tetrahedra linked by bridge oxygen. The thermo-differential analysis shows two endothermic peaks at T1?=?448 and T2?=?919 K. No weight loss was observed in the (TGA) until the temperature 800 K. The conductivity measurements confirm the presence of a phase transition at 448 K accompanied by an important increasing of the conductivity of Cs+ cations and a significant decreasing of the activation energy. 相似文献
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Synthesis and structural characterization by single-crystal X-ray diffraction method, thermal behavior, and electrical proprieties are given for a new compound with a superprotonic phase transition Cs2(HSO4)(H2AsO4). The title compound crystallizes in the monoclinic system with the P21/n space group. The structure contains zigzag chains of hydrogen-bonded anion tetrahedra that extend in the [010] direction. Each tetrahedron is additionally linked to a tetrahedron neighboring chain to give a planar structure with hydrogen-bonded sheets lying parallel to (10ī). The existence of O–H and (S/As)–O bonds in the structure at room temperature has been confirmed by IR and Raman spectroscopy in the frequency ranges 4000–400 cm?1and 1200–50 cm?1, respectively. Differential scanning calorimetry analysis of the superprotonic transition in Cs2(HSO4)(H2AsO4) showed that the transformation to high temperature phase occurs at 417 K by one-step process. Thermal decomposition of the product takes place at much higher temperatures, with an onset of approximately 534 K. The superprotonic transition was also studied by impedance and modulus spectroscopy techniques. The conductivity in the high temperature phase at 423 K is 1.58 × 10?4 Ω?1 cm?1, and the activation energy for the proton transport is 0.28 eV. The conductivity relaxation parameters associated with the high disorder protonic conduction have been examined from analysis of the M”/M”max spectrum measured in a wide temperature range. Transport properties of this material appear to be due to the proton hopping mechanism. 相似文献
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The present paper undertakes the study of (C12H12N)2CuCl4, which is a new hybrid compound. It is synthesized and characterized by single-crystal X-ray diffraction, Hirshfeld surface analysis, and FT-IR, FT-Raman, and impedance spectroscopies. It is crystallized in the monoclinic system with C2/c space group. Its crystal structure was determined and refined down to an R value of 0.05 and a wR value of 0.14. The structure can be described by the alternation of two different, cationic–anionic layers parallel to (110) plan. This complex is assembled into 3D supramolecular architecture by hydrogen bonds (N–H…Cl, C–H…Cl) and π–π interactions. Hirshfeld surface analyses and fingerprint plots are used for decoding intermolecular interactions in the crystal network and contribution of component units for the construction of the 3D architecture. The presence of different functional groups and the nature of their vibrations were identified by FT-IR and FT-Raman spectroscopies. The material is characterized by impedance spectroscopy technique measured in 209–500 MHz frequency and 296–390 K temperature ranges. In addition, the Cole–Cole (Z? versus Z?) plots were well fitted to an equivalent circuit built up by a parallel combination of resistance (R) and constant phase elements (CPEs). The close values of activation energies obtained from the analysis of equivalent circuit data confirm that the transport is through ion hopping mechanism in the bis (4-benzylpyridinium) tetrachlorocuprate. 相似文献
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Mixed crystals Rb3(HSO4)2.5(H2AsO4)0.5 have been prepared by slow evaporation from aqueous solution at room temperature. The crystals were characterized by X-ray single analysis, which revealed that Rb3(HSO4)2.5(H2AsO4)0.5 crystallizes in the space group P with lattice parameters: a = 7.471(3) Å; b = 7.636(1) Å; c = 12.193(2) Å; α = 71.91(1)°; β = 73.04(6)° and γ = 88.77(2)°. In this structure, the ordered S(1)O4 and the disordered S(3)/AsO4 tetrahedra are connected by O–H..O hydrogen bonds, to a zigzag chains running in the b-direction. These chains are, in turn, bonded to one another by disordered hydrogen bridges O–H..H–O, to give a planar structure, with hydrogen-bonded sheets, laying parallel to (1 0 0). Each disordered tetrahedron is linked to a tetrahedron neighbouring S(2)O4 by ordered hydrogen bonds. Broader peaks in IR spectrum of the title material support the assumption of disordered structure. Thermal analysis of the superprotonic transition in Rb3(HSO4)2.5(H2AsO4)0.5 showed that the transformation to the high-temperature phase occurs by one-step process at 404 K. Thermal decomposition of this compound takes place at much higher temperatures, with an onset of approximately 473 K. 相似文献
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Dr. Aurélie Macé Khaoula Hamrouni Dr. Etienne S. Gauthier Marion Jean Dr. Nicolas Vanthuyne Dr. Lucas Frédéric Dr. Grégory Pieters Dr. Elsa Caytan Dr. Thierry Roisnel Dr. Faouzi Aloui Dr. Monika Srebro-Hooper Dr. Bertrand Carboni Dr. Fabienne Berrée Dr. Jeanne Crassous 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(29):7959-7967
Mono- and di-boranil-substituted helicenes were prepared by BF2-borylation of the corresponding anils, readily synthesized by condensation of 2-amino- and 2,15-diamino-helicenes with 4-(diethylamino)salicylaldehyde. After enantiomeric resolution using HPLC, their chiroptical properties including circularly polarized fluorescence in solution and in PMMA films were investigated and rationalized with the help of NMR, X-ray and quantum-chemical calculations. 相似文献
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