bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical and Spectroscopic Studies on the Interaction of Gallocyanine with DNA
Authors: Xu Bai , Jiao Kui , Ren Yong , Sun Wei 
Published: May 2015

AbstractThe interaction of gallocyanine (GC) with double‐stranded DNA (dsDNA) in pH 3.5 Tris‐HCl buffer solution was investigated by electrochemical methods and spectrophotometric methods as well. In the potential scan range of ‐0.25 ˜ +0.18 V(vs. SCE), GC had a couple of well‐defined redox peaks at ‐0.022 V and ‐0.069 V on a cyclic voltammogram at the scan rate of 100.0 mV/s, respectively. After the addition of dsDNA into the GC solution, the redox‐peak currents decreased obviously and the peak potentials shifted positively. The results demonstrated that GC binding to DNA was caused by intercalation. Electrochemical parameters such as the electron number (n), the charge transfer coefficient (α) and the electrochemical reaction standard rate constant (ks) were calculated and compared in the absence and presence of dsDNA. Almost unchanged values of the electrochemical parameters after adding dsDNA showed that non‐electroactive complexes were formed when GC interacted with DNA. The results indicated that the decrease of the redox‐peak currents was caused by the decrease of the free concentration of GC in the reaction solution. The binding constant and binding ratio were investigated by spectrophotometric methods. DNA concentration can be determined by the decrease of the peak current of GC. The linear range for dsDNA was in the range of 1.45 × 10−7 ˜ 1.45 × 10−6mol/Land 1.45 × 10−6 ˜ 1.45 × 10−5 mol/L, respectively with the linear regression equation as ΔiP (10−7 A) = 0.037 + 0.018C (10−7mol/L), and ΔiP (10−7 A) = 0.25 + 0.041C (10−6mol/L), respectively, and the detection limit (3σ) was 1.13 × 10−7 mol/L.
Spectrophotometric Determination of Thioctic Acid in its Dosage Forms through Complex Formation with Pd(II)
Authors: El‐Enany N. , Belal F. , Rizk M. 
Published: May 2015

AbstractA simple and sensitive spectrophotometric method has been developed for the determination of thioctic acid in pharmaceutical preparations. The proposed method is based upon the formation of a complex with palladium(II) in acetate buffer of pH 4.8 with an absorption maximum at 318 nm. The absorbance obeyed Beer's law over the range of 2–20 μg mL−1 with a minimum detection limit of 0.15 μg mL−1 and molar absorptivity (ζ) of 7 × 103 L mol−1.cm−1. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets and ampoules. The results obtained were in good agreement with those obtained using a reference spectrophotometric method. A proposal of the reaction pathway is presented.
Spectrophotometric Determination of the Stability Constant of the Inclusion Complexes of Some Catechol Derivatives with β‐Cyclodextrin Based on Their Reaction with Iodate
Authors: Afkhami Abbas , Khalafi Lida 
Published: May 2015

AbstractThe effects of β‐cyclodextrin (β‐CD) inclusion on the kinetics of the oxidation of several cathechol derivatives, including 4‐tert‐butylcatechol, 3‐methylcatechol and 3‐methoxycatechol, with iodate was studied spectrophotometrically. The rate of the oxidation reactions decreased by increasing β‐CD concentration as a result of inclusion. The stability constants for the inclusion complexes of the investigated compounds were determined based on the changes in the rate constants as a function of β‐CD concentration at pH 3.0. The rate constants for the free and complexed forms and also the stability constants for the inclusion complexes were calculated. The role of the hydrophobic effect was evaluated by studying the influence of the presence of different amounts of ethanol on the β‐CD: guest interaction. In a given H2O‐EtOH mixture the stability of β‐CD complexes shows the order of 4‐tert‐butylcatechol ≈ 3‐methylcatechol ≈ 3‐methoxycatechol. Increasing ethanol content caused a decrease in the stability constant of the inclusion complexes and an increase in observed rate constants.
Application of Tetra Cyclohexyl Tin(IV) as an Anionic Carrier for the Construction of a New Salicylate Membrane Sensor
Authors: Ganjali Mohammad Reza , Norouzi Parviz , Faridbod Farnoush , Rezapour Morteza , Ahmadi Abbas 
Published: May 2015

AbstractA new tin complex namely tetracyclohexyl tin(IV) (TCHT) was synthesized and used as the ion carrier for the construction of a highly selective salicylate sensor. This sensor shows a Nernstian response to salicylate ions over a very wide concentration (1.0 × 10−7–1.0 × 10−1 M) in a pH range of 5.5–10.5. The optimum selectivity and response could be obtained for a membrane incorporating 30% PVC, 61% BA, 3% of cationic additive (HTAB) and 6% of TCHT. The response time of the electrode is very short in the whole concentration range (15 s). The electrode also shows an excellent discriminating ability for salicylate ions with respect to the most common organic and inorganic anions including chloride, sulfate, nitrate, nitrite, cyanide, sulfite, iodide, thiocyanate, phosphate, acetate, oxalate, citrate, and tartarate ions. The detection limit of the proposed sensor is 8.0 × 10−8 M. The electrode was successfully used for determining the concentration of salicylate ion in synthetic serums.
Al Electrode Modified by Au Atoms as a Novel Electrode for Electrocatalytic Oxidation of Thiosulfate
Authors: Sabzi Reza Emamali , Hassanzadeh Ali , Heravi Parvaneh , Ghasemlu Khosrow 
Published: May 2015

AbstractAn aluminum electrode modified with gold atoms was introduced as a novel electrode. Gold atoms were deposited both chemically and electrochemically onto the aluminum electrode to make an aluminum/gold (Al/Au) modified electrode (ME). The experimental results showed that the Al/Au modified electrode prepared by chemical deposition, exhibits much more current than the electrochemical deposition method. The electrochemical behavior of the Al/Au modified electrode was studied by cyclic voltammometry. This modified electrode showed two pairs of peaks, a1c1 and a2c2, with surface‐confined characteristics in a 0.5 M phosphate buffer. The dependence of Epa of the second peak (a2c2) on pH shows a Nernestian behavior with a slope of 55 mV per unit pH. The effect of different supporting electrolytes, solution's pH and different scan rates on electrochemical behavior of Al/Au modified electrode was studied. Au deposited electrochemically on a Pt electrode (Pt/Au) was also used as another modified electrode. A comparative study of electrochemical behavior of bare Al, Pt/Au and Al/Au modified electrodes showed that both Pt/Au and Al/Au electrodes have the ability of electrocatalytic oxidation of S2O32−, but the electrocatalytic oxidation on the latter was better than the former. The kinetics of the catalytic reaction was investigated by using cyclic voltammetry and chronoamperometry techniques. The average value of the rate constant for the catalytic reaction and the diffusion coefficient were evaluated by means of chronoamperometry technique.
Application of Boron as the Chromogenic Agent in Spectrophotometry I. A Novel Fading Spectrophotometric Method for the Determination of Aminomethylbenzoic Acid with Boric Acid
Authors: Li Quan‐Min , Zhang Tian‐Tian 
Published: May 2015

AbstractIt is the first time that boron has been used as a chromogenic agent to determine aminomethylbenzoic acid (PAMBA) by the fading spectrophotometric method in this paper. The study indicates that at pH 10.00 the absorbance of PAMBA decreases when boric acid (BA) is added to the solution. A simple, rapid, sensitive and reliable novel method based on the product of PAMBA and BA is obtained. The stoichiometric ratio of the product is 1:2. Beer's law is obeyed in the range of PAMBA concentrations of 0.13 ˜ 38.40 μg/mL at a wavelength of 242 nm (ε242 is 8.1 × 104 L/mol/cm). The equation of linear regression is A = ‐0.06635 – 0.02914C (× 10−5 M), with a linear correlation coefficient of 0.9974. The detection limit is 0.12 μg/mL and RSD 0.11%. The method is successfully applied to the determination of PAMBA in pharmaceutical samples, and average recoveries from pharmaceutical samples and urine samples were between 98.4 ˜ 102.5%. The other components in these samples do not interfere with the determination by the proposed method.
Determination of Levofloxacin in Human Urine with Capillary Electrophoresis and Fluorescence Detector
Authors: Tsai Yu‐Hsien , Bair Ming‐Jong , Hu Cho‐Chun 
Published: May 2015

AbstractIn this study, we developed an analytical method for the enantioseparation of ofloxacin, using capillary electrophoresis with fluorescence detection. The optimum background electrolyte was obtained to be 60 mM hydroxylpropyl‐β‐cyclodextrin (HP‐β‐CD) in 50 mM phosphate buffer at pH 2.30. Under these conditions, the (+) and (‐) ofloxacin were completely separated, with the detection limit of 10 nM when the sample was prepared in deionized water. The linear ranges of levofloxacin in deionized water and untreated urine were 10−7 to 5 × 10−3 M with R2 = 0.9989 and 5 × 10−6to 5 × 10−3 M with R2 = 0.9943, respectively. We also applied this method to investigate the purity of a commercial drug. The results revealed that the ratio between (+)‐ofloxacin and (‐)‐ofloxacin (levofloxacin) was 99.9:0.1, and there is about 93 mg levofloxacin per tablet (200 mg). The concentration of levofloxacin in patient's urine was founded to be 7.9 × 10−4M, and the ratio between the two optical isomers was 99.3:0.7.
Preparation of Nanostructural ZrO2/SiO2 and Study on Catalytic Activity of its Superacid Catalyst
Authors: Huang Shao‐Yong , Chen Ru‐Fen , Zhang Xu‐Hong , Song Xiu‐Qin 
Published: May 2015

AbstractA novel material ZrO2/SiO2 was synthesized on SiO2 support by means of electrostatic self‐assembly technique and sol‐gel method. After treating this material with 0.7 mol·L−1 H2SO4, a nanostructural solid superacid catalyst SO42−‐ZrO2/SiO2 was prepared. The material was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Brunauer Emmett Teller method (BET) and Hammett indicator method. The catalytic activity of the catalyst was carried out for the esterification between acetic acid and butanol. Results show that the catalytic activity of this catalyst was much higher than that of powdered superacid catalyst SO42−/ZrO2. Due to the SiO2 spherical support, the solid superacid catalyst could be separated and recovered easily. The nanostructural ZrO2/SiO2 will be a promising material for the chemical industry in the future.
Selective Method for the Conversion of Oximes to Their Corresponding Carbonyl Compounds under Microwave Irradiation by N‐Bromo‐N‐Phenyl‐Para‐Toluenesulfonamide
Authors: Khazaei Ardeshir , Sadri Minoo , Hosseini Hassan 
Published: May 2015

AbstractIn this work, oximes are converted to their corresponding carbonyl compounds in good yields using N‐bromo‐N‐phenyl‐para‐toluenesulfonamide, under microwave irradiation. The simple work‐up procedure minimizes loss of product.
Synthesis and Characterization of Novel Monoazo N‐Ester‐1,8‐Naphthalimide Disperse Dyestuffs
Authors: Gharanjig Kamaladin , Arami Mokhtar , Rouhani Shohre , Bahrami Hajir , Movassagh Barahman , Mahmoodi Niyaz Mohammad 
Published: May 2015

AbstractFive novel monoazo disperse dyestuffs based on N‐ester‐1,8‐naphthalimide were synthesized. Acenaphthene was nitrated, then oxidized to 4‐nitro‐1,8‐naphthalic anhydride. 4‐Nitro‐1,8‐naphthalic anhydride was reacted with methyl and ethyl glycinate in alcoholic media, followed with reduction. 4‐Amino‐N‐methyl and ethyl glycinate‐1,8‐naphthalimide were obtained. These products were diazotized and coupled with appropriate aromatic amines to give bluish‐red or violet dyestuffs.All intermediates and dyestuffs were purified and characterized by 1H‐NMR, FTIR, DSC, UV‐VIS and Elemental Analysis. Dispersion of dyestuffs was prepared in water and applied to polyester fabrics. The dyed fabrics showed that four of the synthesized dyestuffs were suitable for coloring polyester fibers, producing deep bluish red with very good build up properties.
New Norcembranoids from the Soft Coral Sinularia Lochmodes
Authors: Tseng Yen‐Ju , Ahmed Atallah F. , Hsu Chi‐Hsin , Su Jui‐Hsin , Dai Chang‐Feng , Sheu Jyh‐Horng 
Published: May 2015

AbstractTwo new C‐4 norcembranoids sinulochmodins D (1) and E (2), along with three known norditerpenoids (3–5), have been isolated from the organic extract of a Taiwanese soft coral Sinularia lochmodes (Kolonko). The structures of 1 and 2 were determined on the basis of extensive spectroscopic analyses and by comparison of their spectral data with those of related metabolites.
Metal Hydrogen Sulfates Catalyzed Methoxymethylation of Alcohols under Solvent‐Free Conditions
Authors: Niknam Khodabakhsh , Zolfigol Mohammad Ali , Shayegh Mohsen , Zare Reza 
Published: May 2015

AbstractMethoxymethylation of a variety of alcohols was performed by using formaldehyde dimethoxy acetal in the presence of metal hydrogen sulfate M(HSO4)n at room temperature and solvent‐free conditions. The methoxymethyl ethers (MOM‐ethers) were obtained with high yields and purity.
Studies on α‐Bromination of Ketone in Hydrindane Ring System
Authors: Yunus Uzma , Winterfeldt Ekkhard 
Published: May 2015

AbstractThe present paper describes the results of various attempts to synthesize 5‐bromo‐6‐ketone (11). When standard procedures for the α‐bromination were tried, a mixture of 5‐bromo‐6‐ketone (11) and 7‐bromo‐6‐ketone (12) was obtained. However, when bromination was carried out under buffered conditions, the desired 5‐bromo‐6‐ketone (11) could be obtained in a good yield.
Synthesis, Characterization, Luminescence, and Electrochemistry of the Tetranuclear Gold(I) Amidinate Clusters, Precursors to CO Oxidation Catalysts: Au4[(ArNC(H)NAr)]4, Au4[(PhNC(Ph)NPh)]4 and Au4[PhNC(CH3)NPh)4]
Authors: Abdou Hanan E. , Mohamed Ahmed A. , Fackler John P. 
Published: May 2015

AbstractA summary of the chemistry of the tetranuclear Au(I) amidinate complexes is presented. Tetranuclear Au(I) amidinate clusters are produced by the reaction of the sodium salt of a amidine ligand with the gold precursor Au(THT)Cl in a (1:1) stoichiometry. The structures of the tetranuclear Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, C6H3‐3,5‐Cl, C6H4‐4‐Me, C6H4‐3‐CF3, C6F5, C10H7 and the tetranuclear Au4[(PhNC(Ph)NPh]4 and Au4[PhNC(CH3)NPh]4 have been characterized by X‐ray crystallography. The average Au···Au distance between adjacent Au(I) atoms is ˜3.0 Å, typical of compounds having an aurophilic interaction. The four gold atoms are located at the corner of a rhomboid with the amidinate ligands bridged above and below the near plane of the four Au(I) atoms. The angles at Au···Au···Au in the cyclic units are between 70° and 116°. The tetranuclear gold(I) amidinate clusters each show different luminescence behavior. The tetranuclear clusters Au4[(ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐3‐CF3, Ar = C6H4‐4‐Me and Ar = C6H4‐3,5‐Cl are the first tetranuclear gold(I) cluster species from group 11 elements that show fluorescence at room temperature. The tetranuclear naphthyl derivative Ar = C10H7 is luminescent only at 77 K. The pentafluorophenyl derivative Ar = C6F5 does not show any photoluminescence in the solid state nor in the solution. The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes. Electrochemical and chemical oxidation studies of the tetranuclear Au(I) amidinate clusters are presented. The tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐4‐Me, and Ar = C6H3‐3,5‐Cl, show three reversible waves at 0.75, 0.95, 1.09 V vs. Ag/AgCl at a scan rate of 500 mV/s in 0.1 M Bu4NPF6/CH2Cl2 at a Pt working electrode in CH2Cl2. Three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s are also observed for the tetranuclear complex Au4[PhNC(Ph)NPh]4 in CH2Cl2. The pentafluorophenyl amidinate derivative, Au4[ArNC(H)NAr]4, Ar = C6F5 shows no oxidation wave below 1.8 V. Recently it has been shown that Au4[ArNC(H)NAr]4 is a very effective catalyst precursor for room temperature CO oxidation.
Tribromoisocyanuric Acid (TBCA) and Oxone®‐MX Systems as Oxidizing Agents: Oxidative Coupling of Thiols to Their Corresponding Disulfides under Mild and Heterogeneous Conditions
Authors: Zolfigol Mohammad Ali , Niknam Khodabakhsh , Bagherzadeh Mojtaba , Ghorbani‐Choghamarani Arash , Koukabi Nadiya , Hajjami Maryam , Kolvari Eskandar 
Published: May 2015

AbstractTribromoisocyanuric acid (TBCA) and Oxone®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields.
Oxidative Methyl Esterification of Primary Alcohols with Iodine‐Mediated Poly[4‐(Diacetoxyiodo)Styrene]
Authors: Liu Xiao‐Ling , Lin Shu‐Ying , Sheng Shou‐Ri , Wei Mei‐Hong , Gong Bin 
Published: May 2015

AbstractAn operationally simple oxidative methyl esterification of primary alcohols in good yields using an iodine‐mediated poly[4‐(diacetoxyiodo)styrene] in methanol at room temperature is described. The polymeric reagent can be regenerated and reused as an environmentally benign reagent.
Computation of Rotation Matrices Making Lined‐Up to the Local Cartesian Coordinates
Authors: Yakar Yusuf , Özmen Ayhan , ÇLakir Bekir , Yüksel Hüseyin 
Published: May 2015

AbstractRotation matrices were expressed in terms of Gaunt coefficients and complex spherical harmonics. The rotation matrices were calculated using two different ways. In the first, Gaunt coefficients and normalized complex spherical harmonics were directly calculated using binomial coefficients; in the second, Gaunt coefficients and complex spherical harmonics were recursively calculated. The methods were compared with respect to accuracy and computation time (CPU) for low and very high quantum numbers.
A Comparison between the Experimental and Theoretical Investigations on Carbon‐13 Isotropic Shielding Constants of Some Tripodal Tetraamine Ligands
Authors: Salehzadeh Sadegh , Bayat Mehdi 
Published: May 2015

AbstractThe direct implementation of GIAO and CSGT methods for calculation of 13C isotropic shielding constants of fully protonated forms of six tripodal tetraamine ligands tren, pee, ppe, tpt, epb and ppb at the Hartree‐Fock level of theory are presented. The shielding constants were determined using hybrid methods (including a mixture of Hartree‐Fock exchange and DFT exchange‐correlation) and are close to the experimental data. A splayed‐like conformation was considered for fully protonated forms of all ligands, and it was confirmed that this is the most stable conformation for the latter form of such ligands. A good linear correlation between the calculated chemical shielding at gas‐phase and experimental shift values in D2O solution was obtained.
Phenolic Compounds from Elsholtzia Bodinieri Van't
Authors: Hu Hao‐Bin , Jian Yu‐Feng , Cao Hong , Zheng Xu‐Dong 
Published: May 2015

AbstractSeven phenolic compounds, including one new compound trans‐3,4,3′,5′‐tetrahydroxy‐4′‐methylstilbene 4‐O‐β‐D‐xylopyranosyl‐(1→6)‐β‐D‐glucopyranoside (1), together with six known compounds (+)‐hinokiol (2), 6‐hydroxy‐5,7‐dimethoxycoumarin (3), caffeic acid (4), vanillic acid (5), 4‐hydroxy‐2,6‐dimethoxyphenol‐1‐O‐β‐D‐glucopyranoside (6) and 4‐allyl‐2,6‐dimethoxyphenol‐1‐O‐β‐D‐glucopyranoside (7), were isolated from the root bark of Elsholtzia bodinieri Van't. Their structures were determined on the basis of spectroscopic and chemical evidence.
Adsorptive Stripping Differential Pulse Voltammetry for Determination of Trace Amounts of Noscapine in Human Plasma
Authors: Niazi Ali 
Published: May 2015

AbstractA new adsorptive anodic differential pulse stripping voltammetry method for the direct determination of noscapine at trace levels in human plasma of addicts is proposed. The procedure involves an adsorptive accumulation of noscapine on a hanging mercury drop electrode (HMDE), followed by oxidation of adsorbed noscapine by voltammetry scan using differential pulse modulation. The optimum conditions for the analysis of noscapine are pH = 8.5 using Britton‐Robinson (B‐R) buffer, accumulation potential of −100 mV (vs. Ag/AgCl), and accumulation time of 150 s. The peak current is proportional to the concentration of noscapine, and a linear calibration graph is obtained at 0.015–2.75 μg mL−1. A relative standard deviation of 1.28% (n = 5) was obtained, and the limit of detection was 7 ng mL−1. The capability of the method for the analysis of real samples was evaluated by determination of noscapine in spiked human plasma and addicts, human plasma with satisfactory results.
Computer Simulation of Eley‐Rideal Reactions Over Rough Surface
Authors: Chaudhari Ajay , Rabbani Gulam , Lee Shyi‐Long 
Published: May 2015

AbstractThe effect of surface roughness on an Eley‐Rideal reaction mechanism is studied. The rough surfaces are generated over a 2‐dimensional square lattice using the random deposition model. In an Eley‐Rideal reaction mechanism, a reacting particle approaches from the bulk and reacts with an active site upon collision with it. Three different rough surfaces are considered for the study. Multifractal scaling analysis is performed where the complex distribution of reaction probabilities is analyzed. Two cases of reactions are considered. 1) The reacting particle reacts at its first contact to the surface and 2) the reacting particle diffuses till it finds the lowest‐height position and reacts. The results obtained from the above two cases are compared. Significant differences between τ(q) and f(α) multifractal spectra for these two cases are found. The larger deviation from linearity in the τ(q) curves for the latter than the former gives wider f(α) spectra, indicating greater heterogeneity in the reaction probability distribution. Dynamic scaling theory is also applied on the Eley‐Rideal reaction mechanism over the surface with different surface roughnesses to obtain the two scaling parameters αd and βd. The values of αd and βd are found to be negative.
Oxidation of 2‐Phenylethylamine with N‐Bromosuccinimide in Acid and Alkaline Media: A Kinetic and Mechanistic Study
Authors: Mohana Kikkeri N. , Ramdas Bhandarkar Paanemangalore M. 
Published: May 2015

AbstractA kinetic study of oxidation of 2‐phenylethylamine (PEA), a bioactive compound, with potent oxidant, N‐bromosuccinimide (NBS) has been carried out in HCl and NaOH media at 313 K. The experimental rate laws obtained are: ‐d [NBS] /dt = k[NBS][PEA][H+] in hydrochloric acid medium and ‐d [NBS]/dt = k[NBS][PEA]x[OH−]y in alkaline medium where x and y are less than unity. Accelerating effect of [Cl−], and retardation of the added succinimide on the reaction rate have been observed in acid medium. Variation of ionic strength of the medium shows negligible effect on rate of reaction in both media. Decrease in dielectric permittivity of the medium decreased the rate in both media. The stoichiometry of the reaction was found to be 1:1 in acid medium and 1:2 in the case of alkaline medium. The oxidation products of PEA were identified as the corresponding aldehyde and nitrile in acid and alkaline medium, respectively. The reactions were studied at different temperatures and the activation parameters have been evaluated. The reaction constants involved in the proposed mechanisms were computed. The reaction was found to be faster in alkaline medium in comparison with the acid medium, which is attributed to the involvement of different oxidizing species. The proposed mechanisms and the derived rate laws are consistent with the observed experimental results.