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991.
Simultaneous Voltammetric Determination of Theophylline and Guaifenesin Using a Multiwalled Carbon Nanotube‐Ionic Liquid Modified Glassy Carbon Electrode 下载免费PDF全文
A glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNTs) and a hydrophobic ionic liquid (IL), was used for the simultaneous voltammetric determination of theophylline (TP) and guaifenesin (GF). The results showed that the oxidations of TP and GF were facilitated at modified electrode and peak‐to‐peak separation at MWCNT? IL/GCE (252 mV) was larger than that observed at unmodified GCE (165 mV). Voltammetric signals for TP and GF exhibited linear ranges of 0.5 to 98.0 µM (R2>0.99) and 1.5 to 480.0 µM (R2>0.99), respectively. The method was used to estimate TP and GF contents in some real samples. 相似文献
992.
Mehdi D. Esrafili Fariba Mohammadian-Sabet Mohammad Solimannejad 《Structural chemistry》2014,25(4):1197-1205
Ab initio calculations were performed to investigate the cooperativity between the S···N(C) bond and the hydrogen/lithium/halogen bond interactions in O2S···NCX···NCH and O2S···CNX···CNH triads (X=H, Li, Cl, and Br). To understand the properties of the systems better, the corresponding dyads are also studied. It is evident that the lithium bond has a bigger influence on the chalcogen bond than vice versa. The results indicate that the enhanced interaction energies of the S···N(C) and X···N(C) interactions in the triad increase in the order NCCl < NCBr < NCH < NCLi and CNCl < CNBr < CNH < CNLi. This is the order of the increasing positive electrostatic potential V S,max on the X atom. The nature of S···N(C) and X···N(C) interactions of the complexes is unveiled by energy decomposition analysis and natural bond orbital (NBO) theory. The cooperativity between both types of interaction is chiefly caused by the electrostatic effects. 相似文献
993.
Farhang Mizani Abbas Shockravi Mehdi Taghdiri Samad Bavili Tabrizi Faezeh Azmoodeh Kamal Alizadeh Mojtaba Shamsipur 《Journal of inclusion phenomena and macrocyclic chemistry》2014,79(1-2):83-94
A novel thia-aza substituted macrocyclic diamide 7,10,13-triaza-1-thia-4,16-dioxa-20,24-dimethyl-2,3;17,18-dibenzo-cyclooctadecane-6,14-dione (L) was synthesized and stability of its complexes with several alkaline earth, transition and heavy metal ions were studied conductometrically in methanol solution. The resulting 1:1 Ag+–L complex found to be the most stable one among all cation complexes studied. The optimized structures of the ligand and its Ag+ complex were also investigated. Based on the preliminary results thus obtained, L was used as an excellent sensing material to prepare polymeric membrane (PME) and coated graphite (CGE) silver-selective electrodes. The electrodes revealed a Nernstian behavior over wide Ag+ ion concentration ranges (i.e., 2.0 × 10?6–1.0 × 10?2 M for PME and 5.0 × 10?7–1.0 × 10?2 M for CGE). The potentiometric responses were independent of pH of the test solution in the range 2.9–6.8. The electrodes possessed advantages of low resistance, relatively fast response time, long lifetimes and, especially, good selectivity relative to a wide variety of other cations. The electrodes were used, as indicator electrodes, in the potentiometric titration of silver ion and in the determination of Ag+ ion in waste water, photographic emulsion, radiographic and photographic films and dental amalgams. 相似文献
994.
Moona Mohsenimehr Manouchehr Mamaghani Farhad Shirini Mehdi Sheykhan Fatemeh Azimian Moghaddam 《中国化学快报》2014,25(10):1387-1391
Novel pyrido[2,3-d]pyrimidine derivatives were synthesized through a one-pot three-component approach using HAp-encapsulated-γ-Fe2O3[γ-Fe2O3@HAp-SO3H]catalyzed condensation of 6-arnino-2-(methylthio or ethylthio)pyrimidin-4(3H)-one,Meldrum's acid and aryl aldehydes at 60 ℃ and under solvent-free conditions.In this protocol the use of nanocatalyst provided a green,useful and rapid method to generate the products in short reaction times and excellent yields(88%-94%). 相似文献
995.
MWCNTs-C-PO_3H_2 has been used as an efficient,heterogeneous and reusable nanocatalyst for synthesis of acylals from aldehydes under solvent-free conditions at room temperature.A wide range of aldehydes was studied and corresponding products were obtained in good to excellent yields in short reaction times.Nanocatalyst can be easily recovered by centrifuge and reused for subsequent reactions for at least five times without deterioration in catalytic activity.The major advantages of the present method are high yields,short reaction time,recyclable catalyst and solvent-free reaction conditions at room temperature. 相似文献
996.
Seyed Karim Hassaninejad-Darzi Mostafa Rahimnejad 《Journal of the Iranian Chemical Society》2014,11(4):1047-1056
Development of a novel modified electrode for electrocatalytic oxidation of methanol in order to decrease overvoltage is importance. In this paper, carbon paste electrode (CPE) was modified by ZSM-5 nanozeolite. The average diameter of used nanozeolite was 97 nm. Ni2+ ions were incorporated to the nanozeolite by immersion of the modified electrode in a 0.1 M nickel chloride solution. Then, electrochemical studies of this electrode were performed by using cyclic voltammetry(CV) in alkaline medium. This modified electrode was used as an anode for the electrocatalytic oxidation of methanol in 0.1 M of NaOH solution. The obtained data demonstrated that ZSM-5 nanozeolite at the surface of CPE improves catalytic efficiency of the dispersed nickel ions toward methanol oxidation. The values of electron transfer coefficient, charge-transfer rate constant, and the electrode surface coverage are obtained 0.61, 0.2342 s?1, and 4.33 × 10?8 mol cm?2, respectively. Also, the mean value of catalytic rate constant between the methanol and redox sites of electrode and diffusion coefficient were found to be 2.54 × 104 cm3 mol?1 s?1 and 1.85 × 10?8 cm2 s?1, respectively. Obtained results from both CV and chronoamperometric techniques indicated that the electrode reaction is a diffusion-controlled process. 相似文献
997.
Mojtaba Bagherzadeh Mojtaba Amini Parviz Gohari Derakhshandeh Mohammad Mehdi Haghdoost 《Journal of the Iranian Chemical Society》2014,11(2):441-446
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. 相似文献
998.
Hamidreza Samouei Mehdi Rashidi Frank W. Heinemann 《Journal of the Iranian Chemical Society》2014,11(4):1207-1216
Reaction of cyclometalated platinum(II) precursor [Pt(C^N)Cl(dmso)], 1, C^N = N(1), C(2′)-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, with 1 equivalent of triphenyl phosphine, PPh3, or 1,3,5-triaza-7-phosphaadamantane, PTA, gave the complex [Pt(C^N)Cl(PPh3)], 2, or [Pt(C^N)Cl(PTA)], 3, respectively. On the basis of careful multinuclear NMR spectroscopy, supported by a number of 2D NMR experiments, structures of the complexes 2 and 3 in solution were determined to be neutral four coordinate. The X-ray crystallography indicated that the solid-state structure of complex 3 comprised a common square-planar geometry around platinum(II). Cytotoxicity of the complexes 2 and 3 was studied in three human cancer cell lines derived from ovarian carcinoma (CH1), lung carcinoma (A549), and colon carcinoma (SW480). 相似文献
999.
Nonlinear Dynamics - The vertically driven pendulum is one of the classical systems where parametric instability occurs. We study its behavior with an additional electromagnetic interaction caused... 相似文献
1000.
In the present work a central composite design based on response surface methodology (RSM) is employed for fine tuning of the aspect ratios of seed-mediated synthesized gold nanorods (GNRs). The relations between the affecting parameters, including ratio of l-ascorbic acid to Au3+ ions, concentrations of silver nitrate, CTAB, and CTAB-capped gold seeds, were explored using a RSM model. It is observed that the effect of each parameter on the aspect ratio of developing nanorods highly depends on the value of the other parameters. The concentrations of silver ions, ascorbic acid and seeds are found to have a high contribution in controlling the aspect ratios of NRs. The optimized parameters led to a high yield synthesis of gold nanorods with an ideal aspect ratio ranging from 1 (spherical particle) to 4.9. In addition, corresponding tunable surface Plasmon absorption band has been extended to 880 nm. The resulted nanorods were characterized by UV–visible spectrometry and transmission electron microscopy. 相似文献