Applied Chemistry Today
Year:2018 | Volume:13 | Issue:48|Papers Count:24

We describe an indirect method for the voltammetric determination of La(III) ion. It is based on competitive extraction of La(III) into an ion-imprinted polymer (IIP) on the surface of a carbon paste electrode (CPE). The nano-sized IIP was synthesized via suspension polymerization in silicone oil and deposited on the CPE. The IIP-modified CPE was then incubated with solutions containing Cu(II) and a solution containing both Cu(II) and La(III) ions. The oxidative stripping differential pulse voltammetric signal for Cu(II) was utilized to determine the competitively extracted quantity of Cu(II). The presence of La(III) reduces the quantity of electroactive lead ions in the IIP located on the CPE. No such effect was observed for the case of a non-imprinted CPE. The effect of various factors on response was optimized. The drop in the signal for Pb(II) as a result of addition of La(III) is proportional to the concentration of La(III). The voltammetric response is linearly related to the concentration of La(III) in the 0. 5 to 70. 0 μ M range, and the detection limit is 0. 1 μ M an SNR of 3. The relative standard deviation is 3. 08 % (for n=5). The electrode is selective for La(III) even in the presence of other lanthanide ions. The method was applied to the determination of La(III) in synthetic and in spiked real samples.

Solubility is one of the important parameters to find out desired concentration of drug in systemic circulation for intended pharmacological properties. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Any drug to be absorbed must be present in the form of solution at the site of absorption. Hence solubility has turned to a major challenge for formulation scientist. In this research polyvinyl alcohol (PVA) fibers loaded with Trimethoprim (TMP) was fabricated by electrospinning and investigated as potential oral fast-dissolving films. Scanning electron microscopy (SEM) images showed that the fibers take the form of uniform cylinders with smooth surfaces and diameter less than 600 nm, and contain the drugs in the amorphous form. Drug– polymer intermolecular interactions were evidenced by infrared spectroscopy (FT-IR) and differential thermal analysis (DTA). Disintegration and drug released times, when they added to artificial saliva, were 30 s and 90 s respectively and during this time more than 90 % of drug was released. In-vitro bacterial inhibition test was also carried out to determine the relative activity of the released antibiotic. The data reported herein clearly demonstrate that these fast-dissolving films could be suitable candidates for administration of TMP, especially for children, aged people and patients with swallowing difficulties.

In this study, biodegradable/biocompatible nanofiber electrospun mats of polylactic acid (PLA), with 8% and 16% of celecoxib (CX), was used for sustained release formulations of CX. After optimize condition, the best solvent for electrospinning of PLA system was chloroform/methanol 20% v/v. The morphology of the nanofiers, distribution of the drug inside the nanofiers and possible reactions between polymers and CX in nanofiers were studied by scanning electron microscopy, X-ray diffraction and fourier transform infrared spectroscopy technics. In vitro CX release from the nanofiber mats were evaluated in solution of HCl (pH = 1. 5), citrate buffer (pH = 3) and carbonate buffer (pH = 8) by using UV-Vis spectroscopy technic. Drug release was dependent to polymer type, CX percent and release environment. CX release in nanofiber mats of PLA with 8% and 16% w/w of CX, was increased, respectively. Korsemeyer-Peppas release exponent (n) indicates that CX release mechanism was non-Fickian diffusion for formulations of PLA nanofiber mats.

Dyes are complex organic compounds, which are widely used in textile, paper, and cosmetics industries. Dyes are also known environmental pollutants that must be removed to maintain environmentally friendly processes. For this purpose the use of advanced oxidation processes with use of highly active compounds such as hydroxyl radicals was proposed. In this study the photocatalytic degradation of BR46 cationic dye with the use of activated carbon-doped ZrO2 nanoparticle was investigated. Parametric study was performed for a range of pH (3– 11), initial dye concentration (5-25 mg/ L), catalyst loading (0. 03– 0. 18 g/ L), and UV lamp power (9-18 W). All testing were done in the 1 L cylindrical pyrex reactor with the height of 460 mm. The maximum removal efficiency of dye of 98. 17% was observed for pH=11, initial concentration of dye = 15 (mg/L), catalyst loading= 0. 15 (g/L) and UV lamp power = 18 W for a retention time of 120 min. The decolorization of BR46 followed the pseudo-first-order kinetic according to the Langmuir– Hinshelwood model (with kr = 1. 135 mg/ L min, ke = 0. 0124 L/ mg).

Chitosan was used as a green support for cobalt(II). Chitosan-cobalt(II) after characterization with common methods including FT-IR, flame atomic absorption spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and thermal gravimetric analysis as a biocompatible heterogeneous catalyst was used in the oxidation reaction of styrene to styrene oxide. The reaction led to the formation of styrene oxide in the presence of the prepared catalyst and excess amounts of hydrogen peroxide as a green oxidant in H2O as the solvent at room temperature during 6 h with 96% yield and high selectivity. Also, the reaction gave high yield in the solvent free conditions. The catalyst is recyclable for six times without any significant decreases in the activity.

In this work, mechanistic study of the electrochemical oxidation of 2, 5-dihydroxybenzoic acid (2, 5-DHBA) and 2, 3-dihydroxybenzoic acid (2, 3-DHBA) in the presence of various nucleophiles have been investigated both experimentally and theoretically. The study was done by the use of cyclic voltammetry, controlled-potential coulometry and Density Functional Theory (DFT). The theoretical results were calculated at DFT (B3LYP and BP86) levels of theory and 6-311+G (p, d) basis set. Results showed that two-electron oxidation of studied species is followed by a Michael addition reaction of nucleophiles and new dihydroxybenzoic acids are produced. Considering several mechanisms indicates that electrochemical oxidation potentials (Ep) of studied species are directly dependent on the Δ Gtot of electrochemical oxidation. It was found that the products which are produced on the surface of electrode, depending on their Δ Gtot of the electrochemical oxidation, will participate in the electrochemical or chemical following reactions.

The present research work Palladium-based electrocatalysts on substrates Vulcan, graphene and MWCNTs were successfully synthesized by using NaBH4 reduction, and their electrocatalytic activity was evaluated in alkaline media. morphology and surface analysis studies with SEM, TEM, EDX, XPS methods. The SEM analysis show rod-like morphology with a dia meterin the nano meter range and length varying in some micro-meter. The TEM images showed the in-crease of nano tube diameter after catalyst deposition. The EDX analysis reveals the presence of (Pd: Vulcane, Graphene and MWCNTs) (20: 80) wt%. Synthesized electrocatalysts studies with electrochemical methods such as CV, EIS, RDE and CA. The CV results confirmed that the Pd/G electrocatalysts caused by an E onset shift to more positive positions, indicating that the good performance of Pd/Graphene electrocatalyst also have the lowest mass transfer resistance and improved the Overvoltage than platinum-carbon as much as 70 mV at 0. 1M sodium hydroxide electrolyte.

A variety of tetrasubstituted pyrroles were synthesized by a one-pot three-component reaction of α-hydroxyketones (benzoin derivatives), malononitrile, and ammonium acetate in good yields under solvent-free conditions. In these reactions silica molybdic acid (SMA) was used as efficient, reusable, green and useful catalyst. The prepared silica molybdic acid (SMA) was characterized by X-ray fluorescence (XRF), powdered X-ray diffraction (XRD), and FT-IR spectroscopy. The attractive advantages of this method are the short reaction times, high yields of the products and reusability of the catalyst. All of these advantages make it a useful strategy for the preparation of various pyrrole derivatives simply by different substrates.

In this study, magnetic nanocomposite of multi-walled carbon nanotube (mMWCNT) was used as adsorbent for removal of Direct Green 26 (DG26) dye. Process optimization was performed using the response surface modeling method based on the Box-Behnkenn experimental design. Adsorbent dosage (1-3 g L-1), pH (2. 5-8. 5) and contact time (25-45 min) were considered as the experimental variables and dye removal efficiency as the response. Results of the regression analysis showed good fit of the experimental data of dye removal process to a quadratic model with coefficient of multiple determination of 0. 9824 and p

Four new penta-coordinated cobalt (III) complexes of general formulae [CoL1-4]ClO4. H2O (where L1= methyl-2-{[1-methyl-2-(2-hydroxyphenyl)methylidynenitrilo]ethyl}-amino-1-cyclopenteneithiocarboxylate, (H2cdsalMeen), L2=methyl-2-{[1-methyl-2-(2-hydroxy-5-clorophenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate, (H2cd5ClsalMeen), L3=methyl-2-{[1-methyl-2-(2-hydroxy-5-bromophenyl)methylidynenitrilo]ethyl}amino-1-cyclopent-enedithiocarboxylate, (H2cd5BrsalMeen), L4=methyl-2-{[1-methyl-2-(2-hydroxy-5-nitrophenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate, (H2cd5NO2salMeen)) were synthesized and characterized by different physico-chemical techniques. The spectroscopic data confirmed the structure of penta-coordinated complexes. The Schiff base ligands coordinated to the cobalt ion through the phenolic oxygen, the both azomethine nitrogen atoms and the sulfur of C-S group acting tetradentate behaviour and the axial donor atom from a tributylphosphin P atom is as a five coordinate. From the elemental analysis data, the stoichiometry of the complexes 1: 1 (metal: ligand) was ascertained. Antibacterial activities of the prepared compounds were evaluated in vitro against Staphylococcus aureus and Escherichia Coli. Their minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) for all synthesized ligands and their cobalt (III) complexes were determined. The ligands and their complexes exhibited significant antibacterial activity. The free ligands showed high activities compared with the CoIII complexes.

In this report for the first time, gold nanoparticles were supported and stabilized on copper ferrite nanoparticles (CuFe2O4 NPs) and obtained compound was characterized by different techniques such as transmission electron microscopy (TEM), X-ray spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Novel prepared material has been applied as a bimetallic and magnetic catalyst in successful coupling reaction of structurally different aldehydes, amines and alkynes for preparation of various propargylamines. Using this catalyst, corresponding propargylamines were obtained in high to excellent yields. Catalyst was successfully recovered by external magnetic field and reused for 6 consecutive runs without decreasing of activity.

Recently, ionic liquids with surface-active properties due to the specific characteristics (such as green solvent) have been considered. In this research, the interfacial and micellization behaviors of binary mixtures of an ionic liquid (1-hexyl 3-methylimidazolium chloride or C6mimCl) and cationic surfactant (Cetyltrimethyl ammonium bromide or CTAB) were studied at various mole fractions (0. 1-0. 9). The surface tension technique was used to determine CMC values of surfactants in pure and mixed states. In the pure components, the weak interactions between C6mimCl and water (compared with CTAB and water) increase the tendency of CTAB to adsorb at the liquid– vapor interface (higher hydrophobicity and lower CMC for CTAB). The Experimental results were analyzed according to the regular solution model developed by Client, Rubingh, Rosen and others. Interaction parameter (β m), mole fractions ( ), activity coefficients ( ) were calculated and analyzed at the micellar phase. Also, the thermodynamic parameters such as maximum surface excess ( max), surface pressure ( )and minimum area per molecule (Amin) calculated and investigated. The results show that the activity coefficients values are less than unity for studied system, indicating non-ideal behavior and attractive interactions between ionic liquid molecules and surfactants in the mixed micelles. Negative interaction parameter (β m) of the systems at the mixed micelle indicates the synergism of the mixing process. By reducing the surface tension (σ ) increased the values of  max (or decreased the values of Amin).

New nanocatalyst Fe3O4@MnPOM, was successfully synthesized by covalent bonding of polyoxomolybdate [PMnMo11O39]5‒ on the amino-functionalized Fe3O4@SiO2. The synthesized nanomaterials were characterized by a series of spectroscopic techniques including X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) and infrared spectroscopy (FT– IR). The resulting nanocomposites were efficient catalyst for selective oxidation of olefins to corresponding epoxides with t– BuOOH as oxidant, in high yields and selectivity. In addition, the synthesized catalyst could be conveniently recovered from reaction mixture using applying an external magnet. The recycling tests showed that the nanocatalyst can be reused at least 7 times without significant loss of catalytic efficiency.

In the present paper, conversion of biomass derived fructose to 5-hydroxymethyl furfural by using sulfated alumina and sulfated nano alumina has been investigated. Preparation of catalysts achieved by sulfonation of Al2O3 and nano-Al2O3 by chlorosulfonic acid. Then, the prepared catalysts were characterized by using BET, SEM, TEM, FT-IR, and TGA techniques. The effect of various parameters such as catalyst type, catalyst loading, solvent, reaction time, reaction temperature and fructose concentration was examined. The best results obtained by using Al2O3-SO3H as the catalyst, the optimum temperature was 130 oC and 4 hours for the reaction time. The maximum 5-HMF yield was obtained 78%.

An efficient, simple and green procedure has been developed for the synthesis of tetrahydrobenzo[b]pyran deravitives via the condensation one-pot and three-component of aldehydes, malononitrile and 5, 5-dimethyl-1, 3-cyclohexandione or 1, 3-cyclohexandione in present heterogeneous catalysts silica-supported antimony(III)chloride (SbCl3/SiO2) and nano catalyst CdO under condition reflux in Ethanol. The advantages this method can be presented to the use of catalysts cheap, accessible, simple separation products, improve the efficiency of products, the use of solvents that are relatively less environmental pollution, an easy way to recyclability and reused catalyst. Also, in present work, (2A-3C-4P-5O-TBP) was used as a platform for dispersion and immobilization of AgNPs on the glassy carbon electrode. The functional groups at (2A-3C-4P-5O-TBP) have effective interaction with silver ions and cause to electrochemical immobilization of AgNPs on the electrode surface. The surface of electrode was investigated by scanning electron microscopy (SEM) and the results showed good distribution of AgNPs on the electrode surface modified with (2A-3C-4P-5O-TBP).

In this manuscript the reaction of 2-mercaptoquinoline-3-carbaldehydes and 1, 1, 3, 3-tetramethyl butylisocyanide as highly substituted isocyanide in the reflux of ethanol without catalyst is described. Formation of C-S, C-C and simultaneously oxidation towards thiophenone derivative is the advantage of this reaction. Also contrary to our impression using hindered isocyanides did not prevent the cyclisation. Only in one example when 2-mercapto quinoline-3-carbaldehyde was used in the reaction, the corresponding alpha keto amide was formed. All of the compounds are new so that they were characterized by mp, FT-IR, H and C-NMR and in some case the structure was confirmed by x-ray single crystallography.

In the present study, Pimpinella affinis was collected from Dodangeh region in Sari (Mazandaran province in Iran). The ethyl acetate extract of leaves of the plant was fractionated byn column chromatography method. THEN, two phytosterols as β-sitosterol (1) and daucosterol (2) were identified using mass (EI-MS) and NMR (1H-NMR and 13C-NMR) spectrometry techniques. These natural sterols have specific biological properties such as anti-HIV, anti-cancer and anti-cholesterol. This study introduced P. affinis as a good source of useful phytosterols. Native people widely use this plant as a vegetable and so the results of this study can be useful for nutrition scientists.

In this paper, polyaniline nanostructurs with different morphologies were synthesized in medium containing ionic liquids (ILs) such as, imidazolium buthyl sulfonate [IMBS], pyridinium chloro acetic acid [PyCAA][Cl] and pyridinium hydrogen sulfate [HPy][HSO4] with various weight ratios of aniline/ILs. Structure and properties of synthesized polyanilines were investigated by using FTIR spectroscopy, UV-Vis, XRD, SEM and TGA. Electrical conductivity and viscosity of synthesized polyanilines were studied by four probe technique and Ubbelohde viscometer, respectively. XRD patterns and SEM images showed that acidic ILs are affected in crystallinity and formation of one and many dimensional nanostructures. Electrical conductivity, solubility, viscosity and thermal stability of synthesized polyanilines in acidic ILs medium are more than that the synthesized polyaniline in standard condition. It seems, ILs as a soft template caused growth and order of polyaniline chains in various morphologies.

Ion selective electrodes (ISE) based on sol– gel process usingtetraethoxysilane(TEOS), diethoxydimethylsilane(DEDMS) and oxalic acid as ionophore, was successfully developedfor detection of Pb2+in aqueous solution. The response of the electrode and also its characterization were estimated by different methods includingpotentiometry measurement, Fourier TransformInfrared (FTIR) and scanning electron microscopy (SEM). The results indicate that the electrode response depends onionophore concentration. In these ion selective electrodes, 0. 5 wt. % oxalic acid gives the best sensitivity for Pb2+. The sol– gel electrodeshows linear response with Nernstian slope of 28. 63 mV/decade toward lead ionover the concentration range 6. 1×10– 6 to 1. 7×10– 2. Also, the electrodes shown detection limits of 1. 0×10− 7 M. The response time of this electrode was obtained 15 sec. at linear dynamic range and lifetime of nearly 2 months. The electrodeis suitable for use in aqueous solutions in a wide pH range of 4– 6. All the obtained results indicate that the proposed lead ion sensor electrode have good reproducibility, repeatability, stability, selectivity and a fast response time.

In this research, a simple and effective method for the synthesis of 1, 5-dihydropyrano[2, 3-c]chromene multi-substituted derivatives has been introduced, using the three-component reaction of aromatic aldehydes, malononitrile and 3-hydroxycoumarin at room temperature and in the presence of polyethylene glycol (PEG-400) as solvent and reaction catalyst. Easy method, short reaction time, high atom economy, high yields, environmental acceptability and the easy of separating of polyethylene glycol are included as the most important advantages of this method. Moreover, the produced products were obtained through simple filtering and no need to column and technique chromatography with high purity. Moreover, the produced products were obtained through simple filtering and no need to column and technique chromatography with high purity.

Mercury is one of the most harmful pollutants. It is very dangerous for human health and environment even in very low concentration. The maximum allowable concentrations of mercury ions reported by the United States Environmental Protection Agency and world health organization are 10 and 30 nM, respectively. So, an ultra-sensitive method is required for mercury level measurement. Traditional methods such as chromatography and spectroscopy, despite of being practical, pose well-known problems. These methods are expensive and time-consuming. So, finding the new methods for determination of mercury ion is one of the most challenges for fabrication of sensitive mercury sensors. In the present work, very sensitive electrochemical aptasensor was fabricated for determination of mercury (II) ion. For this propose graphene oxide was synthesis by the modified hummer method and chitosan-reduced graphene oxide nanocomposite(Chit-rGO) were used for immobilization of mercury aptamer molecules on the surface of modified electrode. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy were used for characterization of synthesized materials and investigation of aptasensor. Under optimal conditions, very sensitive aptasensor with detection limit of 0. 94 nM and linear range of 0. 5-250 nM was fabricated. Results show that fabricated aptasensor can be used for determination of mercury ion in real sample.

Sulfonamides are a class of pharmaceutical compounds included – SO2NH– group that show a variety of biological activities. Sulfacetamide is an N-acyl sulfonamide that has broad-spectrum antibiotic effects. The acid-base properties of these compounds are believed to play an important role in their biological activities. Therefore, calculation of its acidic-basicity has a specific importance in predicting and justifying the pharmaceutical properties of this compound. In this study, the synthesis of sulfacetamide has been carried out from a new multi-steps method in presence of heterogeneous catalyst of nano zinc oxide and homogeneous base catalyst of magnesium hydroxide. The stage and overall yields are better and their reaction time is less than previous procedures. Using heterogeneous catalyst, recoverable nano zinc oxide and magnesium hydroxide in solvent-free condition is a new procedure for better synthesis of this compound. Also in this work, acidic-basicity of sulfacetamide and its derivatives have been studied using high level ab initio calculations. The calculated values have been found in good agreement with experimental data. Therefore, predictions of pharmaceutical properties of these compounds are possible.

In this research, the composite of TiO2/Zeolite as a cheap and effective photocatalyst was prepared for the removal of methyl orange dye in water solution. At first, TiO2 solution was successfully synthesized and then combined with appropriate amount of Clinopatilolite zeolite. The prepared samples were calcined at different temperatures. The synthesized photocatalysts were characterized by, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infrared (FTIR). The effect of the calcination temperatures and the amount of zeolite in composite of the as-synthesized photocatalysts on crystal structure, morphology and photocatalytic degradation of methyl orange dye solution were studied. The results of the experiments showed that combining of zeolite with TiO2 induced the enhancement of photocatalytic activity and optimal zeolite content was obtained about 0. 1 g (0. 33 wt. % ). Also calcination temperature has a great influence on the photocatalytic activity of the synthesized samples. The optimal calcination temperature was obtained 300⁰ C. The composite of TiO2/Zeolite powders obtained from the optimum condition showed uniform spherical shape, anatase crystalline structure and few agglomerates. The methyl orange was removed more than 96% within 60 min of the process with optimum calcinations temperature and zeolite content.

In this study, a new, cheap and green fluorescence sensor based on carbon quantum dots was used for Cr (VI) determination. Carbon quantum dots were synthesized from citric acid, polyvidon and boric acid by microwave assisted method. The size of carbon quantum dots estimated by high resolution transmission electron microscope (HRTEM) and was about 10 nm. Fourier transform infrared spectroscopy (FT-IR) was used for study of functional groups on the carbon dot surface. Synthesized carbon dots had excitation and emission peaks at 340 and 440 nm, respectively. Fluorescence quenching process was occurred after adding of Cr (VI) to synthesized carbon dots solution. At optimum condition (pH=3, t=1 min, excitation and emission slit widths = 10 nm, λ excitation =340 nm and λ emission =440 nm), linear dynamic range and detection limit of this sensor were 5-200 µ M and 1. 24 µ M, respectively. Recovery percent was studied in different real samples such as tap water, river water, mineral water and canned fish.