排序方式: 共有240条查询结果,搜索用时 15 毫秒
151.
Kurt J. Schenk Soraia Meghdadi Mehdi Amirnasr Mohammad H. Habibi Ahmad Amiri Mehdi Salehi Abolfazl Kashi 《Polyhedron》2007,26(18):5448-5457
The synthesis and characterization of a series of cobalt(III) complexes of the general type [Co(N2O2)(L2)]+ are described. The N2O2 Schiff base ligands used are Me-salpn (H2Me-salpn = N,N′-bis(methylsalicylidene)-1,3-propylenediamine) (1–3) and Me-salbn (H2Me-salbn = N,N′-bis(methylsalicylidene)-1,4-butylenediamine) (4–5). The two ancillary ligands L include: pyridine (py) 1, 3-metheylpyridine (3-Mepy) 2, 1-methylimidazole (1-MeIm) 3, 4-methylpyridine (4-Mepy) 4 and pyridine (py) 5. These complexes have been characterized by elemental analyses, IR, UV–Vis, and 1H NMR spectroscopy. The crystal structures of trans-[CoIII(Me-salpn)(py)2]PF6, 1, and cis-α-[CoIII(Me-salbn)(4-Mepy)2]BPh4 · 4-Mepy, 4, have been determined by X-ray diffraction. Examination of the solution and crystalline structures revealed that the outer coordination sphere of the complexes exerts a noticeable influence on the inner coordination sphere of the Co(III) ion. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to CoIII–CoII is electrochemically irreversible, which is accompanied by the dissociation of the axial (R-py)–cobalt bonds. It has also been observed that the Co(III) state is stabilized with increasing the flexibility of the ligand environment. 相似文献
152.
Abolfazl Alizadeh Sahraei Alireza Fathi Mohammad Kazem Besharati Givi Mohammad Hadi Pashaei 《Applied Physics A: Materials Science & Processing》2014,116(4):1677-1686
In this study, copper (Cu) nanocomposites reinforced by coated multiwall carbon nanotubes (MWCNTs) have been fabricated with different weight fractions of MWCNT. In the first step, the as-received MWCNTs were coated with Cu using electroless deposition process. In the next step, combination of sonication and ball milling (with two milling time of 1.5 and 3 h) was used for preparing MWCNT/Cu composite powders. Finally, the disk-shaped specimens were sintered by hot-press sintering machine. Characterization of sintered nanocomposites revealed that increasing milling time led to improved mechanical properties, but higher defect density on the MWCNT sidewalls is obtained which is especially undesirable for electrical properties of nanocomposite. Our results indicated that simultaneous improvements of interface reactions and distribution uniformity of MWCNTs and Cu are key factors for obtaining enhanced mechanical properties. Accordingly, enhancement of up to ~150 and ~86 % in microhardness compared to pure Cu and 1 wt% as-received MWCNT/Cu was achieved by addition of 1 wt% Cu-coated MWCNT. On the contrary, existence of oxygen atoms in the Cu and coated MWCNT interface (from functional groups and deposited copper oxide) obstructs considerable improvement of electrical resistivity compared to as-received MWCNT/Cu nanocomposites. 相似文献
153.
Seyed Abolfazl Hosseini‐Yazdi Ali Akbar Khandar Hashem Azizi Amir Reza Aref 《无机化学与普通化学杂志》2008,634(11):1943-1949
The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N3O3 donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO4)2·6H2O with L afforded [Ni L ](ClO4)2·CH2Cl2 complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl2·6H20 is used, the product complex [{Ni L Cl}2(μ‐Cl)2] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO4)2·6H2O and NiCl2·6H20 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO4)2·6H2O and logK = 3.29 ± 0.06 with NiCl2·6H20). 相似文献
154.
Javad Safaei-Ghomi Hossein Shahbazi-Alavi Abolfazl Ziarati Raheleh Teymuri Mohammad Reza Saberi 《中国化学快报》2014,25(3):401-405
CuI nanoparticles as an efficient catalyst have been used for the preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by the four-component condensation reaction of phthalic anhydride, hydrazine monohydrate, aromatic aldehydes and malononitrile or ethyl cyanoacetate under solventfree conditions in good to excellent yields, short reaction times and environmentally benign, milder reaction conditions. 相似文献
155.
Narges Zohari Mohammad Hossein Keshavarz Seyed Abolfazl Seyedsadjadi 《Journal of Thermal Analysis and Calorimetry》2014,117(1):423-432
A new relationship is introduced between impact sensitivity of energetic compounds and their activation energies of thermal decomposition. In this relationship, the impact sensitivity of an energetic compound with general formula CaHbNcOd is a function of its activation energy of thermal decomposition as well as the ratio of \( \left( {\frac{{n_{\text{H}} }}{{n_{\text{O}} }}} \right) \) and the contribution of specific molecular structural parameters. The new correlation can help us to elucidate the mechanism of initiation of energetic materials by impact. It can be used to predict the magnitude of impact sensitivity of new energetic materials. The new correlation has the root mean square and the average deviations of 2.22 and 1.79 J, respectively, for 40 energetic compounds with different molecular structures. The proposed new method is also tested for 11 energetic compounds, which have complex molecular structures, e.g., 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane and 1,3,7,9-tetranitrophenoxazine. 相似文献
156.
Abolfazl Shakeri Elaheh Amini Javad Asili Milena Masullo Sonia Piacente 《Natural product research》2018,32(12):1436-1440
This study aims to evaluate the in vitro cytotoxic, in vitro and in ovo anti-angiogenic effects and antimicrobial activity of sesquiterpene lactones (SLs) from two plants Centaurea behen and Rhaponticum repens (L.). Five SLs, including cynaropicrin (1), 4β,15-dehydro-3-dehydrosolstitialin A (2), aguerin B (3), janerin (4), cebellin E (5), and a flavone hispidulin (6) were isolated from C. behen (compounds 1–3) and R. repens (compounds 4–6). Cynaropicrin (1) and aguerin B (3) were characterised by strong cytotoxic activities against A2780 cells with IC50 values of 1.15 and 1.62 μg mL?1, respectively, comparable to that of doxorubicin (IC50 = 1.17 μg mL?1). The anti-angiogenic study showed the remarkable inhibitory effect of cynaropicrin (1) and aguerin B (3) on the proliferation and migration of HUVECs. In addition, cynaropycrin and aguerin B exhibited significant angio-inhibitory effects in CAM assay. These findings may be useful for the development of novel chemotherapeutic agents for the treatment of cancer. 相似文献
157.
Hedayat Haddadi Mahboube Shirani Abolfazl Semnani Mohammad Rezaee Hossein Ali Mashayekhi Akram Hosseinian 《Chromatographia》2014,77(9-10):715-721
A new method was developed for the simultaneous determination of deltamethrin and permethrin in water samples with homogeneous liquid–liquid microextraction via flotation assistance and gas chromatography–flame ionization detection. A special extraction cell was designed to facilitate collection of the low density solvent extracts. The sample solution was added into the extraction cell, which contained an appropriate mixture of n-hexane (as an extraction solvent) and acetone (as a homogeneous solvent). Air flotation allowed the extraction solvent to be collected from the top of the solution. Under the optimum conditions, good linearity was observed in the range of 1.0–200 μg L?1 with a correlation coefficient (r 2) greater than 0.9980 for both of the analytes. The limits of detection were 0.2 and 0.3 μg L?1 for deltamethrin and permethrin, respectively (S/N = 3). The developed method was successfully applied to determine the two pesticides in three different water samples. 相似文献
158.
Structural and Solution Studies of two Mercury(II) Complexes with [1,3‐Bis(2‐ethoxy)benzene]triazene
Mohammad Kazem Rofouei Jafar Attar Gharamaleki Ehsan Fereyduni Abolfazl Aghaei Giuseppe Bruno Hadi Amiri Rudbari 《无机化学与普通化学杂志》2012,638(1):220-223
The reaction of [1,3‐bis(2‐ethoxy)benzene]triazene, [ HL ], with Hg(SCN)2 and Hg(CH3COO)2, resulted in the formation of the complexes [Hg L (SCN)] ( 1 ) and [Hg L 2] · CH3OH ( 2 ). They were characterized by means of X‐ray crystallography, CHN analysis, FT‐IR, 1H NMR, and 13C NMR spectroscopy. The structure of compound 1 consists of two independent complexes in which the HgII atoms are stacked along the crystallographic a axis to form infinite chains. Each HgII atom is chelated by one L ligand and one SCN ligand, whereas in compound 2 , the HgII atom is surrounded by two L ligands. In addition, 1D chains formed by metal–π interactions are connected to each other by C–H ··· π stacking interactions in the structure of 1 , which results in a 2D architecture. An interesting feature of compound 2 is the presence of C–H ··· π edge‐to‐face interactions. 相似文献
159.
Mehdi Ghandi Elham MohammadimehrMasoud Sadeghzadeh Abolfazl Hasani Bozcheloei 《Tetrahedron》2011,67(44):8484-8491
An efficient catalyst-free, diastereosective synthesis of novel hexahydro-chromene and tetrahydro-pyrano[2,3-d]pyrimidine-annulated benzo-δ-sultones is described. A number of 2-formyl-4-phenyl (E)-2-phenylethenesulfonates were synthesized and underwent a one-pot domino Knöevenagel-hetero-Diels-Alder reaction, respectively, with dimedone and N,N-dimethylbarbituric acid in water, affording the desired products in moderate to excellent yields. 相似文献
160.
The theoretical study of the dehydrogenation of 2,5‐dihydro‐[furan ( 1 ), thiophene ( 2 ), and selenophene ( 3 )] was carried out using ab initio molecular orbital (MO) and density functional theory (DFT) methods at the B3LYP/6‐311G**//B3LYP/6‐311G** and MP2/6‐311G**//B3LYP/6‐311G** levels of theory. Among the used methods in this study, the obtained results show that B3LYP/6‐311G** method is in good agreement with the available experimental values. Based on the optimized ground state geometries using B3LYP/6‐311G** method, the natural bond orbital (NBO) analysis of donor‐acceptor (bond‐antibond) interactions revealed that the stabilization energies associated with the electronic delocalization from non‐bonding lone‐pair orbitals [LP(e)X3] to δ*C(1) H(2) antibonding orbital, decrease from compounds 1 to 3 . The LP(e)X3→δ*C(1) H(2) resonance energies for compounds 1 – 3 are 23.37, 16.05 and 12.46 kJ/mol, respectively. Also, the LP(e)X3→δ*C(1) H(2) delocalizations could fairly explain the decrease of occupancies of LP(e)X3 non‐bonding orbitals in ring of compounds 1 – 3 ( 3 > 2 > 1 ). The electronic delocalization from LP(e)X3 non‐bonding orbitals to δ*C(1) H(2) antibonding orbital increases the ground state structure stability, Therefore, the decrease of LP(e)X3→δ*C(1) H(2) delocalizations could fairly explain the kinetic of the dehydrogenation reactions of compounds 1 – 3 (k 1 >k 2 >k 3 ). Also, the donor‐acceptor interactions, as obtained from NBO analysis, revealed that the (C(4)C(7)→δ*C(1) H(2) resonance energies decrease from compounds 1 to 3 . Further, the results showed that the energy gaps between (C(4)C(7) bonding and δ*C(1) H(2) antibonding orbitals decrease from compounds 1 to 3 . The results suggest also that in compounds 1 – 3 , the hydrogen eliminations are controlled by LP(e)→δ* resonance energies. Analysis of bond order, natural bond orbital charges, bond indexes, synchronicity parameters, and IRC calculations indicate that these reactions are occurring through a concerted and synchronous six‐membered cyclic transition state type of mechanism. 相似文献