排序方式: 共有68条查询结果,搜索用时 15 毫秒
1.
Abolghasem Moghimi Robabeh Alizadeh Hossein Aghabozorg Abbas Shockravi M. Carla Aragoni Francesco Demartin Francesco Isaia Vito Lippolis Andrew Harrison A. Shokrollahi Mojtaba Shamsipur 《Journal of Molecular Structure》2005,750(1-3):166-173
The one-pot reaction between the novel proton transfer compound (pydaH2)2+(phendc)2−, LH2, and Cu(II) afforded the compounds (pydaH)2[Cu(phendc)2]·10H2O, 1, and (pydaH)2[Cu(phendc)(phendcH)]2·5H2O, 2, where pyda=2,6-diaminopyridine, and phendcH2=1,10-phenanthroline-2,9-dicarboxylic acid. The single crystal X-ray diffraction analysis of 1 and 2 revealed that these are two novel self-assembled 3D Cu(II) complex-organo-networks, in which (pydaH)+ ions and [Cu(phendc)2]2− or complex units are held together by ion pairing, H-bonding, and π–π interactions. Magnetic measurements over the temperature range 1.8–310 K revealed no significant magnetic coupling between Cu(II) centers in 1 or 2. 相似文献
2.
A. Moghimi Sh. Sheshmani A. Shokrollahi H. Aghabozorg M. Shamsipur G. Kickelbick M. Carla Aragoni V. Lippolis 《无机化学与普通化学杂志》2004,630(4):617-624
A novel 1:2 proton transfer self‐associated compound LH2 , (GH+)2(pydc2—), was synthesized from the reaction of dipicolinic acid, pydcH2, (2, 6‐pyridinedicarboxylic acid), and guanidine hydrochloride, (GH+)(Cl—). The characterization was performed using IR, 1H and 13C NMR spectroscopy and single‐crystal X‐ray diffraction. LH2 · H2O crystallizes in the space group C2/c of the monoclinic system and contains eight molecules per unit cell. The unit cell dimensions are: a = 26.480(5)Å, b = 8.055(2)Å, c = 14.068(3)Å. The first coordination complex (GH)2[Cd(pydc)2] · 2H2O, was prepared using LH2 and cadmium(II) iodide, and characterized by 1H and 13C NMR spectroscopy and X‐ray crystallography. The crystal system is triclinic with space group P1¯ with one molecule per unit cell. The unit cell dimensions are: a = 8.5125(7)Å, b = 11.0731(8)Å, c = 13.2404(10)Å. The cadmium(II) atom is six‐coordinated with a distorted octahedral geometry. The two pydc2— units are almost perpendicular to each other. The protonation constants of the building blocks of the pydc‐guanidine adduct, the equilibrium constants for the reaction of pydc2— with guanidine and the stoichiometry and stability of the Cd2+ complex with LH2 in aqueous solution were accomplished by potentiometric pH titration. The solution studies strongly support a self‐association between pydc2— and GH+ with a stoichiometry for the CdII complex similar to that observed for the isolated crystalline complex. In fact, the [Cd(pydc)2]2— complex was found as the most abundant species in solution (> 90 %) at a pH >5. 相似文献
3.
Carbon‐based solid acid was used as a new catalyst for conversion of trimethylsilyl ethers to their corresponding ethers in heterogeneous mixtures. The experiments were done moderately at room temperature, and high yields in suitable times were obtained under these conditions. 相似文献
4.
B. Chahkandi M. Mirzaei M. Chahkandi A. Shokrollahi F. Zarghampour M. Shamsipur 《Journal of the Iranian Chemical Society》2014,11(1):187-198
Three new organic–inorganic hybrid materials based on two important heteropolyoxometalates namely Preyssler (=K12.5H1.5[Na(H2O)P5W30O110]·35H2O) and Wells–Dawson (=K6[P2W18O62]·10H2O) anions, namely, (Hpro)9(Hleu)3K2[Na(H2O)P5W30O110]·25H2O (1), (Hpro)4(Hasp)[HP2W18O62]·20H2O (2), and (Hpro)11K3[Na(H2O)P5W30O110]·18H2O (3) where pro, leu, and asp are proline, leucine, and asparagine, respectively, were prepared and identified by elemental analysis, infrared and proton nuclear magnetic resonance spectroscopies, and thermogravimetric analysis. The hybrid materials are made up of positively charged amino acids, [Na(H2O)P5W30O110]14? and [P2W18O62]6? anions, and H2O molecules of crystallization. These constituents’ fragments held together into a three-dimensional supermolecular network through non-covalent interactions. The protonation constants of the amino acids used, and Preyssler and Wells–Dawson species in all possible protonated forms, the equilibrium constants for binary systems of proline–asparagine and proline–leucine, and the stoichiometry and stability constants of the corresponding binary and ternary hybrids with Preyssler and Wells–Dawson heteropolyoxometalates in aqueous solution were investigated by potentiometric pH titration method. The stoichiometries of the most hybrid species in solution were compared with the corresponding hybrids in the solid phase, in detail. 相似文献
5.
Hamid Reza Safaei Mohsen Shekouhy Athar Shirinfeshan Sudabeh Rahmanpur 《Molecular diversity》2012,16(4):669-683
CaCl2 is applied as an efficient reusable and eco-friendly bifunctional catalyst for the one-pot three-component synthesis of 4H-pyrans under ultrasonic irradiation. A broad range of substrates including the aromatic and heteroaromatic aldehydes, indoline-2,3-dione (isatin) derivatives, acenaphthylene-1,2-dione (acenaphthenequinone) and 2, 2-dihydroxy-2H-indene-1,3-dione (ninhydrin) were condensed with carbonyl compounds possessing a reactive ??-methylene group and alkylmalonates. All reactions are completed in short times, and the products are obtained in good to excellent yields. The catalyst could be recycled and reused several times without any loss of efficiency. 相似文献
6.
Sandra Feisel Joachim von zur Gathen M. Amin Shokrollahi. 《Mathematics of Computation》1999,68(225):271-290
Gauss periods have been used successfully as a tool for constructing normal bases in finite fields. Starting from a primitive th root of unity, one obtains under certain conditions a normal basis for over , where is a prime and for some integer . We generalize this construction by allowing arbitrary integers with , and find in many cases smaller values of than is possible with the previously known approach.
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8.
Kh. Gheisari S. JavadpourH. Shokrollahi B. Hashemi 《Journal of magnetism and magnetic materials》2008
Ferromagnetic powders which are surrounded by an electrically insulating film (soft magnetic composites (SMCs)) exhibit unique magnetic properties, such as relatively low magnetic losses and 3D isotropic magnetic behavior. In some electromagnetic applications, including microwave frequency range applications, it is necessary to increase electrical resistivity without any noticeable reduction in magnetic properties. To achieve this purpose, electrically resistant materials, for example, ferrites with acceptable magnetic properties, are suitable candidates. This paper focuses on the effects of the synthesized Ni–Zn ferrite addition on the magnetic properties of the SMCs containing Ni–Zn ferrite within iron particles. The structure was studied by means of X-ray diffraction (XRD). The microstructure and the powder morphology were examined by the use of scanning electron microscopy (SEM). The magnetic measurements on powders and samples were carried out using a vibrating sample magnetometer (VSM) and an LCR meter, respectively. The results indicate that the lowest magnetic loss and the highest magnetic permeability are related to the composites with 20 wt% ferrite and 2 wt% ferrite, respectively. Also, the composites with 10 wt% ferrite show a good combination of magnetic loss and magnetic permeability in the range 0–500 kHz. 相似文献
9.
Preparation of nanocrystalline Fe–Ni powders by mechanical alloying used in soft magnetic composites
R. Koohkan S. Sharafi H. Shokrollahi K. Janghorban 《Journal of magnetism and magnetic materials》2008
This paper focuses on the preparation of nanocrystalline Fe–Ni powders by mechanical alloying method, which can be used in soft magnetic composites. Fe–10 wt% Ni and Fe–20 wt % Ni alloys were prepared using a high-energy ball mill. The magnetic properties of samples were measured by a B–H curve analyzer and microstructures of the samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bcc Fe(Ni) phase formation was identified by XRD and completed after 45 h of milling. It was found that higher milling time resulted in, larger lattice parameter, higher microstrains and smaller crystallite sizes. Also, results showed that with increasing the milling time, coercivity increased and saturation intrinsic flux density firstly increased noticeably and then decreased in higher milling times (>70 h). 相似文献
10.
Mehrorang Ghaedi Ardeshir Shokrollahi Raziyeh Mehrnoosh Omid Hossaini Mustafa Soylak 《Central European Journal of Chemistry》2008,6(3):488-496
In the presented work, the conditions for cloud point extraction of iron from aqueous solutions using 7-iodo-8-hydroxyquinolin-5-sulphonic
acid (Ferron) was investigated and optimized. The procedure is based on the separation of its ferron complex into the micellar
media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1.0 M HNO3
in methanol. Iron was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities,
incubation time, temperature, viscosity, sample volume, and interfering ions were investigated. The effects of the matrix
ions were also examined. The detection limits for three times the standard deviations of the blank for iron was 0.4 ng m L-1,
enrichment factor of 19.6 and preconcentration factor of 30 could be achieved. The validity of cloud point extraction was
checked by employing real samples including soil, blood, spinach, milk, meat, liver and orange juice samples using the standard
addition method, which gave satisfactory results.In the presented work, the conditions for cloud point extraction of iron
from aqueous solutions using 7-iodo-8-hydroxyquinolin-5-sulphonic acid (Ferron) was investigated and optimized. The procedure
is based on the separation of its ferron complex into the micellar media by adding the surfactant Triton X-114. After phase
separation, the surfactant-rich phase was dissolved with 1.0 M HNO3 in methanol. Iron was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities,
incubation time, temperature, viscosity, sample volume, and interfering ions were investigated. The effects of the matrix
ions were also examined. The detection limits for three times the standard deviations of the blank for iron was 0.4 ng m L−1, enrichment factor of 19.6 and preconcentration factor of 30 could be achieved. The validity of cloud point extraction was
checked by employing real samples including soil, blood, spinach, milk, meat, liver and orange juice samples using the standard
addition method, which gave satisfactory results.
相似文献