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مرکز اطلاعات علمی SID1
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
مرکز اطلاعات علمی SID
Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    285
  • End Page: 

    288
Measures: 
  • Citations: 

    0
  • Views: 

    18431
  • Downloads: 

    4247
Keywords: 
Abstract: 

The Hantzsch method for thiazole synthesis is modified via the reaction of 2-chloro-1, 3-dicarbonyl compounds with 2-(amidosulfanylenemethyl)-1, 1, 3, 3-tetramethylguanidines (prepared in situ from tetramethylguanidine and isothiocyanates), to afford functionalized 2-imino-1, 3-thiazoles in good yields.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    289
  • End Page: 

    295
Measures: 
  • Citations: 

    0
  • Views: 

    17849
  • Downloads: 

    4247
Abstract: 

In this study, three-component reaction of some primary and secondary amines with carbon disulfide in the presence of electron-deficient derivatives of chloropyridine or chlorobenzene in the CH3CN as a solvent is reported. The reaction of primary amines with carbon disulfide and electron-deficient compounds of chloropyridine or chlorobenzene after 6-8 h afforded the three-component addition product. The reaction of secondary amines with carbon disulfide and electron-deficient compounds of chloropyridine or chlorobenzene after 3-4 h afforded the two-component addition product. The product (s) of reactions were purified by recrystallization or column chromatography and their structures were identified by spectroscopy techniques such as 1H-NMR, 13C-NMR, IR, UV and elemental analysis. The reactions were carried out under mild conditions and without using a catalyst.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    297
  • End Page: 

    313
Measures: 
  • Citations: 

    0
  • Views: 

    18306
  • Downloads: 

    4247
Keywords: 
Abstract: 

Eight different di-and triorganotin (IV) complexes of vanillin-Schiff base of the type R2SnClL and R3SnL [R= Me (1,6), n-Bu (2,7), Ph (3,8), tert-Bu (4), Cy (5) and L= 4- ((3,5-dimethylphenylimino) methyl)-2-methoxyphenol] were synthesized. The products were characterized by elemental analysis, FT-IR, 1H, 13C and 119Sn NMR spectroscopy. The ligand 4-((3,5-dimethylphenylimino) methyl)-2-methoxyphenol is also characterized by single crystal X-ray analysis. In the 1H NMR spectra of 1 and 6, the 2J (119/117Sn-1H) in the Sn-CH3 moiety has 57 and 54 Hz values, respectively, that confirm the formation of four-coordinated Sn species. Moreover, the 13C NMR value for ipso carbon of SnPh is 139 ppm which also confirms the formation of four-coordinated Sn species. The title ligand and its complexes were also screened for their biological activities such as interaction with DNA, enzymatic, antimicrobial, cytotoxic and antioxidant activities. The antimicrobial and cytotoxic activities of triorganotin (IV) derivatives are relatively higher than their corresponding diorganotin (IV) analogues due to their greater lipophilicity and permeability through cell membrane.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    315
  • End Page: 

    321
Measures: 
  • Citations: 

    0
  • Views: 

    19966
  • Downloads: 

    4247
Abstract: 

The present study investigates the antioxidant activities of some Romanian plants, using different spectrophotometric methods (FRAP I, FRAP II, and CUPRAC). The plants investigated are hawthorn (Crataegus oxyacantha), bilberry (Vaccinium myrtillus L.), rosehip (Rosa canina), and chokeberries (Aronia melanocarpa). Hawthorn is used to treat a wide variety of inflammatory conditions, but the primary use is generally restricted for treating hypertension, ischemic heart disease, congestive heart failure, and arrhythmia. Investigations have proved the safe and reliable use of plant and plant extracts for treatment of cardiovascular disorders.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    323
  • End Page: 

    333
Measures: 
  • Citations: 

    0
  • Views: 

    16161
  • Downloads: 

    4247
Keywords: 
Abstract: 

Mononuclear copper (II) complexes of 1, 2, 4-triazole-based Schiff base macrocyclic hydrazones, III and IV, have been reported. The prepared amorphous complexes have been characterized by spectroscopic methods, electron spray ionization mass spectrometry, and elemental analysis data. Electrochemical studies of the complexes in DMSO show only one quasi-reversible reduction wave at +0.43 V (DE = 70 mV) and +0.42 V (DE = 310 mV) for III and IV, respectively, which is assigned to the Cu (II) ® Cu (I) reduction process. Temperature dependence of magnetic susceptibilities of III and IV has been measured within an interval of 2-290 K. The values of cM at 290 K are 1.72 × 10-3 cm3 mol-1 and 1.71 ´ 10-3 for III and IV, respectively, which increases continuously upon cooling to 2 K. EPR spectra of III and IV in frozen DMSO and DMF were also reported. The trend g|| > g^ > ge suggests the presence of an unpaired electron in the dx2-y2 orbital of the Cu (II) in both complexes. Furthermore, spectral and antimicrobial properties of the prepared complexes were also investigated.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    335
  • End Page: 

    340
Measures: 
  • Citations: 

    0
  • Views: 

    20566
  • Downloads: 

    4247
Keywords: 
Abstract: 

In this research, Ni2+ supported on hydroxyapatite-core-shell magnetic g-Fe2O3 nanoparticles (g-Fe2O3@HAp-Ni2+) as a novel, efficient, reusable and heterogeneous catalyst was reported. In this protocol, we used this catalyst for the ring opening of epoxide with sodium azide in water. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    341
  • End Page: 

    349
Measures: 
  • Citations: 

    0
  • Views: 

    16622
  • Downloads: 

    4247
Keywords: 
Abstract: 

Two new copper complexes [Cu (Hdpa)2 (en)] (1) and [{Cu2 (m-na)4 (CH3OH)2}. 2CH3OH] (2) (where en is ethylene diamine, Hdpa is 2’-carboxy-[1, 10-biphenyl]-2-carboxylate anion and na is 1-naphtalenecarboxylate) have been synthesized and their crystal structures were determined by X-ray crystallography. Complex 1 was prepared from the reaction of Cu(NO3)2. 3H2O with ethylene diamine and 2, 2’-biphenyldicarboxylic acid in a mixture of water and methanol and complex 2 was prepared from the reaction of CuSO4. 5H2O with 1-naphtalenecarboxylic acid in methanol. The two complexes were characterized by IR, UV-vis, luminescence and elemental analysis. Moreover, complex 2 was characterized by EPR spectroscopy and thermogravimetric analysis. Complex 1 is a monomer and complex 2 is a dimer with a paddle-wheel structure; both structures are without precedent in the literature.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    351
  • End Page: 

    359
Measures: 
  • Citations: 

    0
  • Views: 

    17979
  • Downloads: 

    4247
Keywords: 
Abstract: 

The condensation reaction of 2-aminobenzamide and aldehydes or ketones was investigated in the presence of nanocrystalline sulfated zirconia (SO42-/ZrO2) as solid acid catalyst. SO42-/ZrO2nanoparticles with different calcination temperatures were prepared and characterized by XRD, FT-IR and SEM techniques. The results confirm good stabilization of tetragonal phase of zirconia in the presence of sulfate. The reusability experiments show partial deactivation of the catalyst due to leaching of the sulfate and coke deposition on the catalyst.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    361
  • End Page: 

    367
Measures: 
  • Citations: 

    0
  • Views: 

    20700
  • Downloads: 

    4247
Keywords: 
Abstract: 

A facile and highly efficient protocol for 1,3-dipolar cycloaddition of in situ generated nitrile oxides with terminal alkynes catalyzed by copper-doped silica cuprous sulfate (CDSCS) as a new and convenient heterogeneous nano catalyst is described. In this protocol, 'click' cycloaddition of various structurally diverse alkynes and imidoyl chlorides in the presence of CDSCS and NaHCO3 in a solution of i-PrOH/H2O (1:1, V/V) furnishes the corresponding 3,5-disubstituted isoxazoles in good to excellent yields at room temperature. CDSCS was approved as a chemically and thermally stable nano catalyst that can be recovered and reused for many consecutive trials without considerable decline in its reactivity.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    369
  • End Page: 

    378
Measures: 
  • Citations: 

    0
  • Views: 

    20869
  • Downloads: 

    4247
Abstract: 

A series of indole derivatives has been synthesized and biologically evaluated to identify potent new lipoxygenase (LOX) inhibitors. All selected indole derivatives were screened for their LOX inhibition studies. Most of compounds showed good in vitro LOX inhibition properties exhibiting IC50 values in the range of 53.61±0.14 to 198.61±0.11 mM (mean±SEM), as compared to the standard inhibitor baicalein with IC50 value 22.4±1.3 mM. Structure activity relationship has been discussed and docking stimulation of most active compound 4f has also performed. Thermal stability and melting point of indole derivatives have been performed by thermal gravimetric analysis and differential scanning calorimetry analysis under nitrogen atmosphere at heating rate of 20 °C min-1. Compound 4f bearing bis-phenyl moiety has been found to be the most potent (IC50 53.61±0.14 mM) and thermally most stable among the tested compounds. Imine (C=N) was found to be the key moiety for increasing the thermal stabilities of indole derivatives. FT-IR, NMR and elemental analysis techniques were performed for structural characterization.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    379
  • End Page: 

    389
Measures: 
  • Citations: 

    0
  • Views: 

    15497
  • Downloads: 

    4247
Abstract: 

Co (II), Ni (II) and Cu (II) chloro complexes of benzilic hydrazide (BH) have been synthesized. Also, reaction of the ligand (BH) with several copper (II) salts, including NO3-, AcO-, and SO4- afforded metal complexes of the general formula [CuLX (H2O) n].nH2O, where X is the anion and n = 0, 1 or 2. The newly synthesized complexes were characterized by elemental analysis, mass spectra, molar conductance, UV-vis, IR spectra, magnetic moment, and thermal analysis (TG/DTG). The physic-chemical studies support that the ligand acts as monobasic bidentate towards metal ion through the carbonyl and hydroxyl oxygen atoms. The spectral data revealed that the geometrical structure of the complexes is square planar for Cu (II) complexes and tetrahedral for Co (II) and Ni (II) complexes. Structural parameters of the ligand and its complexes have been calculated. The ligand and its metal complexes are screened for their antimicrobial activity. The catalytic activities of the metal chelates have been studied towards the oxidative decolorization of AB25, IC and AB92 dyes using H2O2. The catalytic activity is strongly dependent on the type of the metal ion and the anion of Cu (II) complexes.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    391
  • End Page: 

    398
Measures: 
  • Citations: 

    0
  • Views: 

    17708
  • Downloads: 

    4247
Keywords: 
Abstract: 

Preparation of antibody-coated gold nanoparticles (GNPs) specific to aflatoxins B1, B2, G1 and G2 and its use in developing aflatoxins diagnostic method were presented in this paper. The formation of gold-labeled antibodies was accomplished at optimal condition. Due to severe overlapping between the emission profiles for the aflatoxins, they cannot be determined by direct inspection of data. The strategy used in this study, constituted by artificial neural network (ANN), was easy to implement and to originate reliable results. ANN can be successfully applied to spectrofluorimetric spectra matrices to simultaneous determination of total aflatoxins. Quantitative results obtained using ANN method for aflatoxins in pistachio nuts samples were compared to those obtained using the HPLC method. Obtained results using these two methods did not show significant differences.

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Writer: 

IZADYAR M.

Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    399
  • End Page: 

    406
Measures: 
  • Citations: 

    0
  • Views: 

    16549
  • Downloads: 

    4247
Abstract: 

In this work, quantum chemistry and kinetics calculations have been performed on the retro-cheletropic ene reactions of N-phenyl-1-methyl-6-methylenecyclohexa-2,4-dienylmethanimine (R1) and N-phenyl-2,2-dimethylbut-3-en (R2). Two major possible mechanisms have been considered and rate constants have been calculated using the transition state theory. The simple Wigner, Eckart zero-curvature tunneling and small-curvature tunneling (SCT) methods were evaluated. The best agreement with experimental rate coefficients was found when SCT correction was applied. A mean deviation of a factor 3 on the rate coefficients is found for the studied reactions at the temperatures of 417 and 773 K. Calculated rate coefficients showed that the tunneling corrections played a critical role in obtaining accurate rate coefficients, especially at lower temperature (417 K). Calculated rate coefficients are in good agreement with the reported experimental data and similar compounds in the case of R1 and R2, respectively. These results support the concerted and stepwise paths for the gas phase reactions of R1 and R2, respectively. Computed kinetic parameters confirmed that R1 had greater reactivity than R2. This trend explains the effects of an extra phenyl-like system on the stability of the transition state and hence increases the R1 rate constant. Calculated rate constants especially at the M06 level are in better agreement with the experimental values than the B3LYP ones. Natural bond orbital (NBO) studies of the reactants and their transition states reveal that their electron delocalization change is an important factor in the determination of the reactivity order for these compounds. Finally, the nature of bond making and breaking during the reactions has been investigated using the concepts of electron charge density and Laplacian in atom in the molecule method.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    407
  • End Page: 

    414
Measures: 
  • Citations: 

    0
  • Views: 

    15363
  • Downloads: 

    4247
Abstract: 

In this paper Cu3Mo2O9 nanosheet was prepared by a hydrothermal method and further used to investigate the direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode (CILE) as the substrate electrode. Hb was mixed with Cu3Mo2O9 nanosheet and cast on the CILE surface with chitosan (CTS) as the film-forming material. UV-vis and FT-IR spectroscopic results showed that Hb remained in its native structure in the composite film. Direct electron transfer of Hb on the modified electrode was realized with a pair of well-defined quasi-reversible redox waves that appeared on cyclic voltammograms. The redox peak potential appeared at -0.252 V (E pc) and -0.141 V (E pa), respectively, with the formal peak potential calculated as -0.196 V, which was the characteristic of electroactive center of Hb heme Fe (III)/Fe (II). The result could be attributed to the presence of Cu3Mo2O9 nanosheet on the electrode surface that was of benefit for the protein orientation and promoted direct electron transfer between the redox active center of Hb and the substrate electrode. The CTS/Cu3Mo2O9-Hb/CILE showed good electrocatalytic ability in reducing different substrates such as trichloroacetic acid, H2O2 and O2, with wider linear range and lower detection limit, thus exhibiting the potential application of the Cu3Mo2O9 nanosheet in third-generation electrochemical biosensors.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    415
  • End Page: 

    422
Measures: 
  • Citations: 

    0
  • Views: 

    17125
  • Downloads: 

    4247
Abstract: 

A highly sensitive method for the determination of manganese (VII), chromium (VI) and nickel (II) in medicinal herb samples is proposed. The method is based on analytes reacted with ammonium pyrrolidinedithiocarbamate (APDC) to give hydrophobic chelates (M-APDC), which were separated and enriched by cloud-point extraction (CPE) with non-ionic surfactant Tergitol TMN-6 as extractant. The surfactant-rich phase containing the chelates is determined with a high-performance liquid chromatography system. To achieve the best CPE method, the Box–Behnken design was used to study the concentration of Tergitol TMN-6, equilibrium temperature, equilibrium time as well as their interaction. What followed was the individual research for the pH of the sample solutions and the concentration of APDC. What is more, in the given optimized experimental conditions, calibration plots were found to be linear in the range of 0.0200-0.500 mg/L for Mn (VII) and Cr (VI), meanwhile 0.0500-1.00 mg/L for Ni (II), the linear correlation coefficients were between 0.996 and 0.999, the recoveries ranged from 91.8 to 97.8 % and the relative standard deviations were between 1.09 and 2.30 %(n= 3). The limits of detection were 0.164 mg/L for Mn (VII), 0.562 mg/L for Cr (VI) and 5.12 mg/L for Ni (II), respectively. The proposed method was applied to determine manganese (VII), chromium (VI) and nickel (II) in medicinal herb samples with satisfactory results.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    423
  • End Page: 

    429
Measures: 
  • Citations: 

    0
  • Views: 

    16398
  • Downloads: 

    4247
Keywords: 
Abstract: 

Some tetradentate N2O2 Schiff base ligands, such as N,N'-bis(naphtalidene)-1,2-phenylenediamine, N,N'-bis(naphtalidene)-4-methyl-1,2-phenylenediamine, N,N'-bis(naphtalidene)-4-chloro-1,2-phenylenediamine, N,N'-bis(naphtalidene)-4-nitro-1,2-phenylenediamine, N,N'-bis(naphtalidene)-4-carboxyl-1,2-phenylenediamine, and their uranyl complexes were synthesized and characterized by 1H NMR, IR, UV–Vis spectroscopy, TG (thermogravimetry), and elemental analysis (C.H.N.). Thermogravimetric analysis shows that uranyl complexes have very different thermal stabilities. This method is used also to establish that only one solvent molecule is coordinated to the central uranium ion and this solvent molecule does not coordinate strongly and is removed easier than the tetradentate ligand and also trans oxides. The electrochemical properties of the uranyl complexes were investigated by cyclic voltammetry. Electrochemistry of these complexes showed a quasireversible redox reaction without any successive reactions. Also, the kinetic parameters of thermal decomposition were calculated using Coats-Redfern equation. According to Coats-Redfern plots the kinetics of thermal decomposition of the studied complexes is first-order in all stages. Anticancer activity of the uranyl Schiff base complexes against cancer cell lines (Jurkat) was studied and determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide) assay.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    431
  • End Page: 

    440
Measures: 
  • Citations: 

    0
  • Views: 

    15880
  • Downloads: 

    4247
Abstract: 

Two new branched pentadentate amines (N5), 3,6-bis (2-pyridylmethyl)-5 methyl-3,6-diazaheptane diazahexane-1-amine (1) and 4,7-bis (2-pyridylmethyl)-6-methyl-4,7-diazaheptane-1-amine (2) have been prepared. These have been used for the synthesis for the eight new macroacyclic Schiff base complexes, by template [1+1] condensation of pyridine-2-carbaldehyde or O-vaniline and amines (1 and 2) in the presence of Mn (II) and Zn (II) metal ions in methanol. The isolated complexes were characterized by a combination of microanalysis, IR and Mass spectroscopy. The structure of MnL1 (ClO4)2 indicates that in the solid state the Mn (II) ion adopts a slightly distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epidermidis and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The structure of the complexes derived from pyridine-2-carbaldehyde and metal-ligand interactions in these complexes were also theoretically studied. It was indicated that the structure of complexes is similar to each other and metal-ligand interactions depend mainly on the nature of metal ion and is similar for this series of ligands.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    441
  • End Page: 

    446
Measures: 
  • Citations: 

    0
  • Views: 

    22170
  • Downloads: 

    4247
Abstract: 

The glucose-based ligand, N-salicylidene-D-glucosamine (Sal-D-glsmN), was readily obtained by reaction of salicylaldehyde (Hsal) with the D-glucosamine hydrochloride. Ligand Sal-D-glsmN was found to be an efficient ligand in the palladium-catalyzed Suzuki and Heck C-C coupling reactions in aqueous medium under aerobic condition. It was found that the use of Sal-D-glsmN/Pd (OAc)2 system as a catalyst, aryl halides undergo Suzuki and Heck cross-couplings, respectively, with arylboronic acids and olefins to give the desired products in moderate to excellent yields.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    447
  • End Page: 

    456
Measures: 
  • Citations: 

    0
  • Views: 

    17263
  • Downloads: 

    4247
Keywords: 
Abstract: 

In this study, a potentiometric sensor based on a pencil graphite electrode (PGE) coated with polypyrrole doped with Titan yellow dye (PPy/TY) was prepared for potentiometric determination of magnesium ion in aqueous solutions. The structural characteristics of magnesium sensor electrode (PGE/PPy/TYMg) were studied using scanning electron microscopy and Fourier transform infrared along with energy-dispersive spectroscopy. Under the optimal conditions, the electrode reveals a good Nernstian behavior with slope of 28.27±0.40 mV per decade over the concentration range of 1.0´10-5-5.0´10-2 M and a detection limit of 6.28´10-6 M. The potentiometric response of fabricated electrode toward magnesium ion was found to be independent of the pH of the test solution in the pH range of 4.5-8.0. The electrode showed fast response time (<10 s) and good shelf lifetime (>2 months). The prepared magnesium sensor electrode can also be used as an indicator electrode in potentiometric titration of Mg2+ with EDTA with distinguished end point. The electrode revealed good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The introduced magnesium electrode was used for measurement of Mg2+ ion in real samples without any serious interferences from other ions.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    457
  • End Page: 

    465
Measures: 
  • Citations: 

    0
  • Views: 

    15814
  • Downloads: 

    4247
Keywords: 
Abstract: 

Nanostructures of Sb-doped ZnO with 0.00, 0.03, 0.06, 0.10 and 0.15 mol fractions of Sb+3 ions were prepared by a one-pot method in water under microwave irradiation for 5 min. Powder X-ray diffraction studies display that the nanostructures are excellently crystallized in the form of Wurtzite hexagonal crystalline phase and doping Sb+3 ions does not change structure of ZnO. Moreover, size of the nanostructures decreases with increasing mole fraction of Sb+3 ions. Scanning electron microscopy and transmission electron microscopy images show that morphology and size of the nanostructures are changing with mole fraction of the dopant. In Fourier transform infrared spectra, intensity of the characteristic peak corresponding to Sb-O bond gradually increases with mole fraction of Sb+3 ions. UV-vis diffuse reflectance spectra of the nanostructures are similar to each other and they have a maximum of about 357 nm. Photocatalytic activity of the nanostructures was investigated by degradation of methylene blue under UV irradiation. For the nanostructures with 0.10 mol fraction of Sb+3 ions, the degradation rate constant increases nearly two times relative to pure ZnO. In addition, influence of various operational parameters on the degradation activity was investigated and the results were discussed.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    467
  • End Page: 

    470
Measures: 
  • Citations: 

    0
  • Views: 

    15128
  • Downloads: 

    4247
Keywords: 
Abstract: 

A series of poly (L -lactic acid)/ poly (ethylene glycol) triblock copolymers with a PLA-PEG-PLA architecture were synthesized by a ring-opening polymerization (ROP) process. The copolymers were characterized by 1H NMR and GPC. The total number average molecular weights were in the range of 4,700-50, 000,whereas the degrees of polymerization of the PLA and PEG blocks varied from 15 to 359 and from 68 to 136, respectively. The self-association of these copolymers in aqueous environment was studied by emission fluorescence spectroscopy of anilinonaphthalene probe and the critical association concentration (CAC) of the copolymers was measured. It was found that the micellization process of these copolymers was mainly determined by the length of the hydrophobic LA block, while the length of the hydrophilic PEG block had little effect. Furthermore, the low CAC values of the copolymers suggest that the copolymers form stable supramolecular structures in aqueous solutions.

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  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    471
  • End Page: 

    479
Measures: 
  • Citations: 

    0
  • Views: 

    13613
  • Downloads: 

    4247
Abstract: 

Mixtures of acetylsalicylic acid (ASA), paracetamol (PAR), and caffeine (CAF) have been successfully analyzed by constrained multivariate curve resolution-alternating least squares (MCR-ALS). The MCR-ALS methodology adequately exploits the second-order advantage which enables quantitation of analyte in the presence of unknown and uncalibrated interferences. The procedure simultaneously takes into account the spectroscopic and pH-dependent properties of the compounds, which leads to a higher selectivity. Specially, for CAF determination fully protonated or deprotonated forms of CAF are not dominant in the pH range of data acquisition but spectral changes with pH were recorded and used for accurate determination of CAF. Furthermore, quantitative determination of an analyte in a complex mixture is performed using a synthetic solution as standard containing only the analyte of interest. Even in the presence of the rank deficiencies, in most cases accurate quantitation with relative errors in prediction lower than 5% was obtained. The procedure was successfully applied to the analysis of real samples (pharmaceuticals) using synthetic external standards. Percent relative errors of 4.03, 3.26, and 5.85 were obtained for ASA, PAR, and CAF, respectively, in A.C.A tablets and 4.49 and 2.75 for PAR and CAF, respectively in Novafen capsules.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    481
  • End Page: 

    487
Measures: 
  • Citations: 

    0
  • Views: 

    13866
  • Downloads: 

    4247
Keywords: 
Abstract: 

A new class of fused tricyclic benzo [4,5] imidazo [1,2-a] -pyrimidine-3-carboxamide derivatives was synthesized via an environmentally benign one pot sequential four-component condensation reaction of an amine, 2,2,6-trimethyl-4H -1,3-dioxin-4-one, an aldehyde and 1H-benzo [d] imidazol-2-amine without using catalyst in good yields.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    489
  • End Page: 

    498
Measures: 
  • Citations: 

    0
  • Views: 

    13444
  • Downloads: 

    4247
Abstract: 

The potential removal and preconcentration of lead (II), cadmium (II), and chromium (III) ions from wastewaters were investigated and explored. Magnetite nanoparticles were chemically modified with p -nitro aniline. The aniline-coated magnetite nanoparticles (ANMNPs) were fully characterized by FT-IR, XRD, SEM, and TEM measurements. Batch studies were performed to address various experimental parameters for the removal and determination of these ions. ANMNPs showed high tendency to investigated metal ions, in this order: Cr (III)>Cd (II)>Pb (II), owing to the strong contribution of surface loaded aniline. The potential applications of ANMNPs adsorbent for removal and preconcentration of Pb (II), Cr (III), and Cd (II) from wastewaters as well as drinking tap water samples were successfully accomplished giving recovery values of (98–101 %), without any noticeable interference of the wastewater or drinking tap water matrices.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    499
  • End Page: 

    510
Measures: 
  • Citations: 

    0
  • Views: 

    24129
  • Downloads: 

    4247
Keywords: 
Abstract: 

We demonstrate herein the modification of magnetic nanoparticles and their use as a magnetic nanocatalyst in direct coupling reactions of aryl halides with terminal alkynes. Magnetite particles were prepared by simple co-precipitation method in aqueous medium, and then Fe3O4@SiO2 nanosphere was synthesized by using nano- Fe3O4 as the core, TEOS as the silica source and PVA as the surfactant. Fe3O4@SiO2 was coated with polymeric N-heterocyclic carbene/Pd. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometer and N2 adsorption-desorption isotherm analysis. Poly (N-vinyl imidazole) functionalized Fe3O4@SiO2 nanoparticle was found to be an efficient nanocatalyst in Sonogashira-Hagihara cross-coupling reactions. The nanocatalyst can be easily recovered by a magnetic field and reused for six runs without appreciable loss of its catalytic activity.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    511
  • End Page: 

    521
Measures: 
  • Citations: 

    0
  • Views: 

    19823
  • Downloads: 

    4247
Keywords: 
Abstract: 

A simple and sensitive differential pulse voltammetry (DPV) procedure, based on a simple modified electrode; carbon-ceramic electrode (CCE) modified with a thin film of single-walled carbon nanotubes (SWCNT), for the simultaneous determination of paracetamol (PC) and caffeine (CAF) was developed. The SWCNT/CCE displayed excellent electrochemical catalytic activities toward PC and CAF oxidation compared with bare CCE. In DPV technique both PC and CAF give sensitive oxidation peaks at 0.71 and 1.38 V vs. saturated calomel electrode, and under the optimized experimental conditions PC and CAF show linear response over the concentration ranges of 0.08–200.0 mM (R2=0.991) and 0.41–300.0 mM (R2=0.990), respectively. The limits of detection (S/N= 3) for PC and CAF were 0.05 and 0.29 mM, respectively. The investigated method showed good stability, reproducibility, repeatability, and high recovery in some real samples.

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Writer: 

KAUR NAVJEET

Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    523
  • End Page: 

    564
Measures: 
  • Citations: 

    0
  • Views: 

    17177
  • Downloads: 

    4247
Abstract: 

The development of new strategies for synthesis of five-membered S-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in sulfur-containing five-membered heterocyclic compounds synthesis is presented, focusing on the developments in the last 5-10 years. This contribution covers the literature concerning the total synthesis of five-membered S-heterocycles under microwave and combined effect of microwave and solid-phase.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    565
  • End Page: 

    578
Measures: 
  • Citations: 

    0
  • Views: 

    17260
  • Downloads: 

    4247
Abstract: 

Chemically modified Lagenaria vulgaris shell was applied as a new sorbent for the removal of lead (II) ions from aqueous solution in a batch process mode. The influence of contact time, initial concentration of lead (II) ions, initial pH value, biosorbent dosage, particle size and stirring speed on the removal efficiency was evaluated. Biosorbent characterization was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four kinetic models (pseudo-first order, pseudo-second order, Elovich model and Intraparticle diffusion model) were used to determine the kinetic parameters. The experimental results were fitted to the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models of isotherm. Pseudo-second order kinetic model and Langmuir isotherm model best fitted the experimental data. Sorption process is obtained to be fast and equilibrium was attained within 40 min of contact time. The maximum sorption capacity was 33.21 mg g-1. Biosorption was highly pH-dependent where optimum pH was found to be 5. The results of FTIR and SEM analysis showed the presence of new sulfur functional groups. This study indicated that xanthated Lagenaria vulgaris shell could be used as an effective and low-cost biosorbent for the removal of lead (II) ions from aqueous solution.

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Writer: 

BAHAR S. | HOSSEINI H.

Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    579
  • End Page: 

    586
Measures: 
  • Citations: 

    0
  • Views: 

    16162
  • Downloads: 

    4247
Abstract: 

A solid-phase extraction procedure is presented for the separation and preconcentration of trace levels of Pd (II) ion by using exfoliated graphene nanosheets (GNs). Experimental parameters such as extraction time, pH, type of eluent, sample volume and temperature were studied in detail. The Pd (II) adsorbed on the GNs was eluted with 1.5 mol L-1 sodium thiosulfite and then determined by flame atomic absorption spectrometry. The effects of potentially interfering ions on the recovery of Pd (II) were also examined. Under optimized conditions, the method provided a preconcentration factor of 100, had a linear range from 5.0 to 100 ng mL-1 of Pd (II), a limit of detection 2.1 ng mL-1, and a relative standard deviation 1.1 % at 20 ng mL-1 of Pd (II). The method was validated by the extraction and determination of Pd (II) in water, tea, lentil and bovine liver samples.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    587
  • End Page: 

    592
Measures: 
  • Citations: 

    0
  • Views: 

    20644
  • Downloads: 

    4247
Keywords: 
Abstract: 

Preyssler-type heteropolyacid supported on TiO2 nanoparticles has been explored as an efficient catalyst in selective oxidation of primary aromatic amines to azoxy derivatives using trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane as oxidant. The reactions proceeded smoothly under mild and green ultrasound-accelerated conditions to afford the products in high yields. The catalyst recovered from the reaction mixture exhibits long-term stability with no significant drop in its catalytic activity.

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Writer: 

YU ANGYANG

Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
  • Issue: 

    2
  • Start Page: 

    593
  • End Page: 

    598
Measures: 
  • Citations: 

    0
  • Views: 

    20927
  • Downloads: 

    4247
Keywords: 
Abstract: 

The fluorine atom's reaction with silane molecule (SiH4) is investigated in this work. Two reaction channels which form SiH3+HF and SiH3F+H are discussed in the microscopic level. The analyses of transition states show that the SiH3+HF channel proceeds through a direct hydrogen abstract mechanism and the SiH3F+H channel could take place via the substitution mechanism. The energetic information of the potential energy surface has been obtained using high-level ab initio molecular orbital theory. A dual-level direct dynamics method is employed to calculate the rate constants of the title reaction. The rate constants of the hydrogen abstraction channel are much larger than the substitution channel. The calculated rate constants are in best agreement with available experimental result.

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