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排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
Awatef Ayadi Amani Jaafar Adeline Fix-Tailler Ghassan Ibrahim Gérald Larcher Abdelkrim El-Ghayoury 《Tetrahedron》2017,73(25):3554-3563
The synthesis of two tetrathiafulvalene-appended pyridinehydrazone pyrimidine ligands, namely (Z)-4-(2-((5-([2,2′-bi(1,3-dithiolylidene)]-4-yl)pyridin-2-yl)methylene) hydrazinyl)-6-chloropyrimidine L1 and (Z)-4-(2-((6-([2,2′-bi(1,3-dithiolylidene)]-4-yl)pyridin-2-yl)methylene) hydrazinyl)-6-chloropyrimidine L2 is described. Ligand L1 was reacted with cobalt(II) to yield a cationic metal complex [Co(L1)2] while ligand L2 was reacted with zinc(II) to afford a neutral metal complex [ZnL2Cl2]. The crystal structure analysis of [Co(L1)2] indicate that Co(II) ion is coordinated by six nitrogen atoms from two perpendicular ligands while in [ZnL2Cl2], Zn(II) is coordinated by two chlorine atoms and three nitrogen atoms. The electrochemical behavior indicate that ligands L1 and L2 and the zinc(II) complex are suitable fort the preparation of crystalline radical cation salts. Finally the determination of MIC80 values against C. albicans, C. glabrata, C. parapsilosis, C. krusei and E. dermatitidis revealed that the cobalt(II) metal complex [Co(L1)2] is active against all the studied fungi. 相似文献
2.
Oleh Stetsiuk Abdelkrim El-Ghayoury Francesc Lloret Miguel Julve Narcis Avarvari 《Molecules (Basel, Switzerland)》2021,26(8)
Four new compounds of formulas [Cu(hfac)2(L)] (1), [Ni(hfac)2(L)] (2), [{Cu(hfac)2}2(µ-L)]·2CH3OH (3) and [{Ni(hfac)2}2(µ-L)]·2CH3CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN2O4 surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χMT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm−1] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm−1] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS1·S2). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties. 相似文献
3.
1,4-Diacetylpiperazine-2,5-dione (1) was condensated with aldehydes (2) with KF on alumina without solvent under microwaves or in at room temperature in the presence of DMF. The reaction was stereoselective and some natural products (4a-c) like albonursin(4c) were synthesized. 相似文献
4.
Smaail Radi Ahmed Attayibat Abdelkrim Ramdani Maryse Bacquet 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):232-241
The immobilization of a thiophene-based tripodal ligand, with a donor sulfur, on the surface of an epoxide group containing a silica gel phase for the synthesis of a newly functionalized material based on porous silica-bound bi-thiophene tripodal ligand (SGBT) is described. The modified silica surface was characterized by 13C NMR of a solid sample, elemental analysis, and infrared spectra. This new material was also studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and BJH pore sizes, respectively. The target material exhibits good thermal stability as determined by thermogravimetry curves. The synthesized material was utilized in column and batch methods for adsorption of Hg2+, Cd2+, Pb2+, Cu2+, Zn2+, K+, Na+, and Li+, and the material exhibits an affinity only towards toxic heavy metals. 相似文献
5.
Abdelkrim Azzouz Vasilica-Alisa Aruş Nicoleta Platon Kamel Ghomari Ieana-Denisa Nistor Tze Chieh Shiao René Roy 《Adsorption》2013,19(5):909-918
Dendrimers bearing hydroxyl groups supported by layered double hydroxides (CO3–LDH) with Mg/Al ratio ranging from 1:1 to 5:1 showed improved properties for the reversible capture of carbon dioxide (CO2). The adsorption capacity of the starting LDH was due to the intrinsic base-like behavior, and was found to depend on the Mg/Al ratio. When contacted with polyol dendrimers in aqueous media, no intercalation took place. This was explained in terms of low exfoliation grade of LDH and hydrophobic character of the dendrimer molecules. The latter rather adsorb on the external surface of the LDH stacks for low dendrimer loadings, or aggregate into organic clusters for higher contents. Analyses through thermal programmed desorption of CO2 revealed that dendrimer incorporation advantageously attenuates the basicity strength of the starting LDH support, by lowering the desorption temperature. The OH groups of the organic moiety were found to display an amphoteric character, and act as the main adsorption sites. The weak interactions with CO2 facilitate easier release of the major part of adsorbed CO2 at temperature not exceeding 80–100 °C. On polyol organo-LDHs, the reversible CO2 retention was discussed herein in terms of acid–base interactions. This concept allows envisaging the capture of diverse pollutants and other greenhouse gases by modifying the chemical groups on the dendritic moiety. 相似文献
6.
Abdelkrim El Kadib 《Chemical record (New York, N.Y.)》2020,20(8):753-772
Tremendous interest was recently devoted to the preparation of porous and functional materials through sustainable route, including primarily the use of renewable biopolymers instead of petroleum‐sourced synthetic chemicals. Among the biopolymers available in enormous quantity, chitosan – obtained by deacetylation of chitin – stands as the sole nitrogen‐containing cationic amino‐sugar carbohydrate. This distinctively provides chitosan derivatives with plenty of opportunities in materials science. Particularly, its pH switchable solubility allowed the preparation of three‐dimensional entangled nanofibrillated self‐standing microspheres. These porous hydrogels behave as nano‐reactors to confine exogenous nanoobjects within the polysaccharide network, including sol‐gel metal alkoxide species, organometallic derivatives and isotropic and oriented nanoparticles. Besides, the interfacial interplay of chitosan with lamellar clay and graphene oxide allowed the penetration of the biopolymer inside of the galleries, which result in a complete delamination of the layered nanomaterials. The preserved gelation memory of chitosan in these formulations provides a way to access porous microspheres entangling exfoliated nanometric sheets. CO2 supercritical drying of functional hydrogel beads enabled efficient removal of water and other liquid solvents without wall collapsing, allowing large‐scale preparation of millimetric hydrocolloidal microspheres with an open macroporous network. These functionalized lightweight biopolymer aerogels find applications in heterogeneous catalysis, sensing, adsorption, insulation and for the design of other sophisticated porous nanostructures. Beyond their tailorable molecular and textural‐engineering, the possibility for macroscopic shaping of these intriguing nanostructures opens many new opportunities, especially in additive‐manufacturing for soft and hybrid robotics. 相似文献
7.
Amel Zitouni Abdelkrim Gouasmia Sabrina Bouguessa Lakhémici Kaboub Louiza Boudiba 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1744-1754
A new series of tetrathiafulvalene (TTF) molecules with extended π-system was prepared by using a Wittig reaction to generate the TTF key. The process of deprotection-alkylation of thiolates provided access to a wide variety of molecules. The study of their reducing power was carried out by cyclic voltammetry. Charge transfer complexes have also been chemically prepared by using TCNQ as an electron acceptor; the electrical conductivity of their compressed powders shows insulator behavior. The IR spectra of the TCNQ salts were recorded and used to characterize and estimate the degree of charge transfer of these complexes. GRAPHICAL ABSTRACT 相似文献
8.
Mourad Ibrahim Daoudi Abdelhafid Triki Abdelkrim Redjaimia 《Journal of Thermal Analysis and Calorimetry》2011,104(2):627-633
Kinetics of β″ and β′ precipitations in an AlSiMg have been studied under non-isothermal conditions using differential scanning
calorimetry (DSC) technique. The variation of the activation energy as a function of transformed fraction is determined using
two isoconversional methods of Kissinger–Akahira–Sunose (KAS) and Friedman. The results obtained using the two methods show
a change in the activation energy for both metastable phases precipitations as a function of transformed fraction. The results
obtained from KAS method as compared with those obtained from Friedman method, show some major disagreements between the two
methods. The growth exponent, determined by Ozawa method, decreases as a function of temperature for both phases. 相似文献
9.
Allag Abdelkrim Sa d Rahmane Ouahab Abdelouahab Attouche Hafida Kouidri Nabila 《中国物理 B》2016,25(4):46801-046801
This article presents the elaboration of tin oxide(SnO_2) thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction(XRD), atomic force microscopy(AFM), ultravioletvisible(UV–Vis) transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction(XRD) patterns show that SnO_2 film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the(110) plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO_2 thin films are found to be in a range of 3.64 e V–3.94 e V. Figures of merit for SnO_2 thin films reveal that their maximum value is about 1.15 × 10-4-1?atλ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10-2?·cm. 相似文献
10.
Yuxin Liu Abdelkrim Talbi Bahram Djafari-Rouhani El Houssaine El Boudouti Lucie Drbohlavová Vincent Mortet Olivier Bou Matar Philippe Pernod 《Physics letters. A》2019,383(13):1502-1505
The interaction of Love waves with square array of pillars deposited on a cavity defined in a 2D holey phononic crystal is numerically investigated using Finite Element Method. First, the existence of SH surface modes is demonstrated separately for phononic crystals that consist of square arrayed holes, or rectangular arrayed Ni pillars, respectively in, or on, a SiO2 film deposited on a ST-cut quartz substrate. The coupling between SH modes and torsional mode in pillars induces a transmission dip that occurs at a frequency located in the range of the band-gap of the holey phononic crystal. Second, a cavity is constructed by removing lines of holes in the holey phononic crystal and results in a transmission peak that matches the dip. The optimal geometrical parameters enable us to create a coupling of the cavity mode and the localized pillar mode by introducing lines of pillars into the cavity, which significantly improved the efficiency of the cavity without increasing the crystal size. The obtained results will pave the way to implement advanced designs of high-performance electroacoustic sensors based on coupling modes in phononic crystals. 相似文献