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排序方式: 共有238条查询结果,搜索用时 15 毫秒
1.
Chlorophyll b was extracted from Heliotropium europaeum plant, then immobilized on magnetic nanoparticles (Fe3O4@SiO2@Chl-Mg) and found as an efficient and green catalyst for the preparation of a variety of benzimidazoles and spirooxindoles in mild conditions. The catalyst was fully characterized by Fourier-transform infrared (FTIR), ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric (TGA), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) analyses. To prove the catalytic influence of Mg over the reactions, the catalytic activity of the demetalated chlorophyll b as well as some other control experiments was investigated. High to excellent yields were achieved for all entries, whether benzimidazole or spirooxindole derivatives at short reaction times. The catalyst could be recovered and reused for several consecutive runs by a simple external magnetic field without any considerable reactivity loss. The properties of the recovered catalyst were investigated by various analyses. Finally, the reasonable mechanisms were proposed for the reactions based on the literature. 相似文献
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Abdelghani Mahmoudi Silvia De Francia Prasanta Paul 《Journal of separation science》2023,46(21):2300424
Clarithromycin is a very important macrolide antibiotic used to treat bacterial infections in human and veterinary medicine. This study reports the development and validation of cost-effective, simple, precise, accurate, and robust high-performance liquid chromatography (HPLC) for the determination of clarithromycin (CLA) in tablets. Reversed-phase chromatography was conducted using a standard column at 55°C with ultraviolet detection at 215 nm. A mobile phase consisting of acetonitrile –2-methyl-2-propanol –potassium phosphate buffer was used at a flow rate of 1.0 mL/min. The proposed method displayed good linearity, precision, accuracy, robustness, and specificity. The present HPLC was compared with capillary electrophoresis and bioassay methods and the results indicated that there was no significant difference between these methods. Moreover, the obtained results demonstrated the validity of the isocratic HPLC, which allows reliable quantitation of CLA in pharmaceutical samples. Thus, it can be used as a substitute alternative methodology for the routine quality control of this medicine, in situations where other methods are less accessible in the laboratory. 相似文献
4.
S.?DehghanpourEmail author A.?Mahmoudi S.?Shadpour 《Russian Journal of General Chemistry》2015,85(5):1167-1173
The surfactant assisted hydrothermal process for selective preparation of copper nanosheets and ultralong microwires by reducing Cu2+ with 2-(bis-phosphonomethylamino)propionic acid (dpc) under the action of cetyltrimethylammonium bromide (CTAB) or polyvinyl pyrrolidine (PVP) is presented. X-ray powder diffraction (XRD) and energy dispersive X-ray analysis (EDX) indicate that the products are pure Cu of cubic phase. The effects of starting material concentration and reaction time on morphology of nanosheets have been studied by scanning electron microscopy (SEM). The presence of CTAB and PVP as capping agents is identified by EDX, transmission electron microscopy (TEM) and FT-IR. The possible growth process for ultralong microwires was studied by stopping the growth at a series of intermediate morphology stages based on SEM observations. Optical properties of Cu nanosheets and ultralong microwires were studied by UV-Vis spectrophotometry. 相似文献
5.
Investigating the nature of intermolecular and intramolecular bonds in noble gas containing molecules 下载免费PDF全文
This article presents a theoretical study on a number of selected noble gas containing systems of the general formula FNgR and NgR (Ng = He, Ne, Ar, Kr, Xe and R = CH3, CN, CCH, BO, BNH, H, BeO, and AuF). The principal structures, bond energies, spectroscopic, and electronic properties of 28 noble gas containing molecules were investigated using density functional theory at the BMK level. Quantum theory of atoms in molecules, natural bond orbital, and several other analysis methods have been used to provide more insight into the nature of noble gas bonds. Although both F? Ng and Ng? R bonds in the investigated molecules are assigned to have partially covalent and partially electrostatic nature, the covalent character is dominant in Ng? R bonds. In the second part, the intermolecular interactions between FNgR molecules and hydrogen fluoride are overviewed with emphasis on the hydrogen bonding through the fluorine side of noble gas molecule with hydrogen of HF. The calculated interaction energies were found to decrease in magnitude going down the noble gas series. For all noble gases, the strongest hydrogen bond has been observed in the case R=CH3. On the contrary, using R=CN in the FNgR moiety weakens the interaction strength. © 2014 Wiley Periodicals, Inc. 相似文献
6.
Ghodrat Mahmoudi Habibar Chowdhury Samuel E. Lofland 《Journal of Coordination Chemistry》2017,70(12):1973-1983
Two coordination polymers, [Mn2(μ-L1)2(μ-N3)2]n (1) and [Mn(μ-HL2)(SCN)2]n (2), were assembled in a single-pot from MnCl2·4H2O, HL1 (2-acetylpyridine isonicotinoylhydrazone) or HL2 (2-acetylpyridine nicotinoylhydrazone) and ancillary ligand sources (NaN3 or NH4NCS). The products were fully characterized, including by single-crystal X-ray diffraction, which revealed a 2-D metal–organic layer in 1 and a 1-D zigzag coordination chain in 2. Both 1 and 2 are constructed from six-coordinate Mn(II) nodes that adopt distorted octahedral (MnN5O) environments; the adjacent nodes are driven by the μ-L1 and μ-N3 linkers in 1 or μ-HL2 linkers in 2 to form different metal–organic networks. Their topological classification was performed, disclosing the hcb and 2C1 topology in 1 and 2, respectively. Different weak non-covalent interactions promote dimensionality extension. Variable-temperature magnetic susceptibility measurements were carried out, revealing weak ferromagnetic and antiferromagnetic interactions in 1 and 2, respectively. 相似文献
7.
Mojtaba Abbasian Nafiseh Khakpour Aali Solmaz Esmaeily Shoja 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):966-975
A method to prepare zinc oxide (ZnO) nanoparticles with a covalently bonded poly(methyl methacrylate) (PMMA) shell by surface initiated atom transfer radical polymerization (ATRP) was reported. First, the initiator for ATRP was covalently bonded onto the surface of zinc oxide nanoparticles through our novel method. Firstly, the surface of ZnO nanoparticle was treated with 3-aminopropyl triethoxysilane, a silane coupling agent, and then this functionalization nanoparticle was reacted with α-chloro phenyl acetyl chloride to prepare atom transfer radical polymerization macroinitiator. The metal-catalyzed radical polymerization of MMA with ZnOmacroinitiator was performed using a copper catalyst system to give the ZnO-based nanoparticles hybrids linking PMMA segments (poly (methyl methacrylate)/zinc oxide nanocomposite). These hybrid nanoparticles had an exceptionally good dispersability in organic solvents and were subjected to detailed characterization using FTIR, TEM and TGA and DSC analyzed. 相似文献
8.
Samaneh Mahmoudi‐GomYek Davood Azarifar Masoumeh Ghaemi Hassan Keypour Masoumeh Mahmoudabadi 《应用有机金属化学》2019,33(6)
A novel Cu (II) Schiff‐base complex immobilized on core‐shell magnetic Fe3O4 nanoparticles (Fe3O4@SPNC) was successfully designed and synthesized. The structural features of these nanoparticles were studied and confirmed by using various techniques including FT‐IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X‐Ray diffraction (XRD), wavelength dispersive X‐ray spectroscopy (WDX), and inductively coupled plasma (ICP). These newly synthesized nanoparticles have been used as efficient heterogeneous catalytic system for one‐pot multicomponent synthesis of new pyrano[2,3‐b]pyridine‐3‐carboxamide derivatives. Notably, the catalyst could be easily separated from the reaction mixture by using an external magnet and reused for several successive reaction runs with no significant loss of activity or copper leaching. The present protocol benefits from a hitherto unreported MNPs‐immobilized Cu (II) Schiff‐base complex as an efficient nanocatalyst for the synthesis of newly reported derivatives of pyrano[2,3‐b]pyridine‐3‐carboxamide from one‐pot multicomponent reactions. 相似文献
9.
Nafiseh Mansouriieh Mahmoud Reza Sohrabi Morteza Khosravi 《Arabian Journal of Chemistry》2019,12(8):2524-2532
This study synthesized bimetallic Fe/Ni nanoparticles and used them for catalytic degradation of profenofos, an organophosphorus pesticide. This novel bimetallic catalyst (Fe/Ni) was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis spectroscopy (EDAX) and X-ray diffraction (XRD). The bimetallic nano-catalyst was prepared at diameters of 20–50 nm and was shown to effectively degrade profenofos. A three-factor central composite design combined with response surface methodology was used to maximize profenofos removal using the bimetallic system. A quadratic model was built to predict degradation efficiency. ANOVA was used to determine the significance of the variables and interactions between them. Good correlation between the experimental and predicted values was confirmed by the high F-value (16.38), very low P-value (<0.0001), non-significant lack of fit, an appropriate coefficient of determination (R2 = 0.936) and adequate precision (14.75). The highest removal rate attained was 94.51%. 相似文献
10.
Sadra Mahmoudi Bahram Hashemi Shahraki 《Journal of Dispersion Science and Technology》2019,40(1):33-42
This paper concerns with developing of parameters which influence terminal velocities of air and CO2 bubbles in distilled water and kerosene pools. The objective of this study is to validate and correct the formulas that were developed by previous investigators for prediction of terminal velocities. The investigation revealed that the terminal velocity of a single rigid spherical bubble in Newtonian fluids can be developed by balancing of mechanical forces acting on the bubble. However, for large bubbles, because of deforming of the bubble which is a result of interfacial tension, the effect of surface tension should be considered in the terminal velocity prediction formula. By using PSO algorithm and plotting experimental data of terminal velocity against the size of gas bubbles, the suitable equation for each of systems was chosen. Results showed that Jamialahmadi model is more practical for terminal velocity prediction. Jamialahmadi model requires a modification to be utilized for air-kerosene, CO2-kerosene, air- distilled water and CO2-distilled water systems. The developed PSO algorithm model is accurate for prediction of experimental data with an average R2 value of 0.9722. 相似文献