排序方式: 共有137条查询结果,搜索用时 31 毫秒
21.
Hassan Hadadzadeh S. Jamil A. Fatemi Seyedeh Raziyeh Hosseinian Hamid Reza Khavasi Rainer Pöttgen 《Polyhedron》2008
The structure, spectroscopy and electrochemical properties of a novel dinuclear copper(II) complex, [{Cu(phen)2}2(μ-CH3COO)][PF6]3 where phen = 1,10-phenanthroline, is reported. The crystal structure contains two independent Cu(II) ions, with different geometry around each copper center, which are bridged by an acetate anion. The acetate-bridged ligand shows a syn–anti coordination mode with a trigonal bipyramidal geometry for the Cu(1) center and a distorted square-based pyramidal geometry for the Cu(2) center. The angular structural index parameter τ for Cu(1) and Cu(2) is 0.9 and 0.33, respectively. The copper(II) atoms display a different geometry with a N4O chromophore group and with Cu–O distances of 1.993(5)–1.996(5) Å and Cu–N distances which vary from 1.980(5) to 2.161(6) Å. The intra Cu…Cu separation is 4.9904(5) Å. The effective magnetic moment (μeff) of the complex was measured by the Evans method. The cyclic voltammogram of [{Cu(phen)2}2(μ-CH3COO)][PF6]3 shows two waves at positive potential which are assigned to the two Cu(II/I) reduction couples. 相似文献
22.
Iraj Mohammadpoor-Baltork Majid Moghadam Shahram TangestaninejadValiollah Mirkhani Seyedeh Fatemeh Hojati 《Polyhedron》2008
12-Tungstophosphoric acid (TPA) supported on silica, activated carbon and poly(4-styrylmethyl)pyridinium chloride (PMP) were found to be highly efficient catalysts for the synthesis of oxazolines, imidazolines and thiazolines from the condensation of various nitriles with aminoalcohols, ethylenediamine and cisteamine, respectively. In the case of oxazolines, dicyanobenzenes were selectively converted to mono- and bis-oxazolines in the presence of these catalysts. In the reaction of dicyanobenzenes with ethylenediamine, only mono-imidazolines were produced and the remaining cyano group did not react even with long reaction times. In the case of thiazolines, only bis-thiazolines were produced in the reaction of dicyanobenzenes with cysteamine. Furthermore, these catalysts could be recovered and reused without significant loss of their activities. 相似文献
23.
Payam Osooli Yadollah Yamini Mahmoud Tabibpour Seyedeh Sara Nasrollahi Nasser Nikfarjam 《Journal of separation science》2023,46(22):2300421
In the present work, a novel solid-phase microextraction on a screw (MES) was employed to extract cationic dyes (malachite green, methylene blue, and rhodamine B) from food samples and fish breeding pool water. The sulfonated poly(styrene-co-divinylbenzene) was electrophoretically deposited on the surface of the grooves of a screw. Then the screw was placed inside a silicon tube as a holder to create a channel to run a test solution through it. The extracted dyes on the coated screw were eluted by a suitable eluent. High-performance liquid chromatography with an ultraviolet/visible detector was utilized for the separation and analysis of the analytes. The effective parameters of the analyte extraction efficiency were optimized. Under optimum conditions, the limits of detection were 0.15 μg/L, and calibration curves were linear in the range of 0.50–250.00 μg/L, with coefficients of determination > 0.989 for all studied dyes. The relative standard deviations of intra and inter-day (n = 3) were in the range of 2.8%–7.0% and 7.0%–9.5%, respectively. The MES was applied as a simple and repeatable method with acceptable relative recoveries (82.0%–103.0%) for the determination of cationic dyes in grape nectar, ice pop, jelly powder, and fish breeding pool water. 相似文献
24.
A. Abbas L. Paria S. Abbas 《The European Physical Journal C - Particles and Fields》2000,14(4):695-698
We use a group theoretical technique to project out the partition function for a system of quarks, antiquarks and gluons
onto a particular representation of the internal symmetry group SU(3): the colour singlet, colour octet and colour 27-plet, at finite temperature. We do this to calculate the thermodynamic
quantities for those representations. We also calculate the change in free energy of the plasma droplet formed from the hot
hadronic gas. We find that the size of the droplet in the colour-octet representation is smaller than that in the colour-singlet
representations at different temperatures in the vicinity of the critical temperatures of the phase transitions.
Received: 1 February 1999 / Revised version: 24 February 2000 / Published online: 18 May 2000 相似文献
25.
Hamzavi Seyedeh Fazileh Jamili Shahla Yousefzadi Morteza Mashinchian Moradi Ali Amrollahi Biuki Narges 《Molecular diversity》2020,24(4):985-995
Molecular Diversity - In this work, we reported a facile synthesis of Pt nanoparticles (NPs) on proline-functionalized cross-linked chitosan particles to catalyze the reduction of R-NO2 to R-NH2 in... 相似文献
26.
Hamzavi Seyedeh Fazileh Gerivani Sanaz Saeedi Simin Naghdipari Kobra Shahverdizadeh Gholamhossein 《Molecular diversity》2020,24(1):201-209
Molecular Diversity - In this research, the cellulose–copper(II) oxide composite particles were provided by a novel and simple approach using Schweizer’s reagent via dialysis method at... 相似文献
27.
Seyedeh Mahboobeh Yousefi Farzaneh Shemirani Sohrab Ali Ghorbanian 《Chromatographia》2018,81(8):1201-1211
In this work, we evaluated the applicability of hydrophobic carboxylic acid-based deep eutectic solvents (DESs) as environmentally friendly alternatives to common organic solvents in microextraction methods based on solidification of floating drop (SFD). Due to the limited number of solvents that can be used in SFD, the introduction of new solvents can help in the development of these attractive methods. Deep eutectic solvents consisting of tetra-n-butyl ammonium bromide (TBAB) and carboxylic acids were prepared and used as extraction solvent. They had the desirable characteristics such as low density, suitable freezing point and proper hydrophobicity which make them suitable alternatives to conventional organic solvents for SFD. With the help of the synthesized hydrophobic DESs, a simple, fast, efficient and environmentally friendly microextraction method was developed based on solidification of deep eutectic solvent (SFDES) without using any organic solvent. The proposed organic solvent-less microextraction method based on SFDES was applied in the analysis of polycyclic aromatic hydrocarbons (PAHs) as model compounds in environmental water samples. By coupling this method with high-performance liquid chromatography–fluorescence detection, we achieved low LOD values which is a necessity in the ultra-trace analysis of PAHs in environmental water samples. Under the optimized conditions, good linearity and low limits of detection of 0.7–6.6 ng L?1 were obtained. The analysis of six PAHs in real water samples gave acceptable relative recoveries ranging from 83 to 117% with 5.4–10.5% intra-day relative standard deviations (RSD) and 4–7.1% interday RSD. 相似文献
Graphical Abstract
28.
Seyedeh Mozhgan Behgozin Mohammad Hossein Fatemi 《Journal of the Iranian Chemical Society》2018,15(6):1293-1300
The maximum steady-state flux of 79 compounds (substituted benzenes, and quinolones and their derivatives) with a wide range of polarity through a PDMS membrane was predicted using a comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) methods. Moreover, the contribution of partial atomic charge to mass transport phenomena was further verified by the correlation of atomic charge to apparent permeability through polydimethylsiloxane (PDMS) membranes. The obtained results indicated superiority of CoMSIA model over CoMFA model. The best CoMSIA model is developed based on the combination of electrostatic and hydrophobic and H-bond acceptor fields (CoMSIA-EHA). The contour maps of electrostatic and hydrophobic and H-bond acceptor fields of CoMSIA model provide an interpretable and logical relationship between chemicals structure and their fluxes, which give useful insights for designing new compounds with higher penetration through the membranes. 相似文献
29.
The synthesis and catalytic application of a novel MgO containing periodic mesoporous organosilica with ionic liquid framework (MgO@PMO‐IL) is described. The prepared MgO@PMO‐IL was characterized by Fourier transform‐infrared spectroscopy, N2 adsorption/desorption, transmission electron microscopy, field emission‐scanning electron microscopy, thermogravimetric and inductively coupled plasma analyses. This nanocatalyst was successfully applied as a highly efficient and recoverable catalyst for the synthesis of novel spirooxindole‐furan derivatives via the three‐component reaction of 1,3‐dicarbonyl compounds, N‐phenacyl pyridinium salts and isatin derivatives. The products were achieved in high to excellent yields with a simple work‐up procedure and short reaction times, and the catalyst could be recovered through a simple filtration process and successfully reused seven times without any significant decrease in its efficiency. 相似文献
30.
Polypyrrole/Fe3O4/CNT as a recyclable and highly efficient catalyst for one‐pot three‐component synthesis of pyran derivatives
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Polypyrrole (PPY)/Fe3O4/CNT has been synthesized and characterized by FT‐IR, TEM and SEM techniques and its catalytic activity has been evaluated in the synthesis of several series of pyran derivatives. Tetrahydrobenzo[b]pyranes, 4H‐pyran‐3‐carboxylates, 4H,5H‐pyrano[3,2‐c]chromenes and dihydropyrano[2,3‐c]pyrazoles have been successfully prepared from one‐pot three‐component condensation of aldehyde, malononitrile and active methylene‐containing compounds (dimedone /ethyl acetoacetate/4‐hydroxycoumarin/3‐methyl‐2‐pyrazoline‐5‐one) using PPY/Fe3O4/CNT as a new and reusable heterogeneous catalyst. The present method offer several advantages such as; high yields of products, short reaction times, easy work‐up procedure and easy separation of the catalyst from the reaction mixture due to its magnetic character. Furthermore, chemoselective synthesis of bis‐benzo[b]pyran from terephthalaldehyde can be achieved by this method. 相似文献