bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Kinetic‐Spectrophotometric Determination of Nb(V) and Ta(V) Using H‐Point Standard Addition Method
Authors: Afkhami Abbas , Zarei Ali Reza 
Published: May 2015

AbstractA simple, rapid, precise and accurate kinetic method for simultaneous spectrophotometric determination of Nb(V) and Ta(V) is described. This method is based on the difference between the rate of the reaction of Nb(V) and Ta(V) with 4‐(2‐pyridylazo)resorcinol (PAR) in the presence of tartaric acid. H‐point standard addition method (HPSAM) was used to resolve the mixtures. The results showed that Nb(V) and Ta(V) can be determined simultaneously in the ranges of 0.10–5.0 and 0.50–12.0 μg mL−;1, respectively. The proposed method was successfully applied to the simultaneous determination of Nb(V) and Ta(V) in several alloy samples.
Synthesis, Spectroscopic and Electrochemical Studies of Novel Transition Metal Complexes with Quadridentate Schiff Base
Authors: Temel Hamdi , İlhan Salih , Aslano ǧlu Mehmet , Kiliçl Ahmet , Taş Eşref 
Published: May 2015

AbstractA novel quadridentate, N2O2 type Schiff base, synthesized from 1,4‐bis‐(o‐aminophenoxy)butane and 2‐hydroxynaphthalin‐1‐carbaldehyde, forms stable complexes with transition metal ions such as Co(II), Cu(II) and Ni(II) in DMF. Microanalytical data, elemental analysis, magnetic measurements, UV‐visible and IR‐spectra as well as conductance measurements were used to confirm the structures. Electrochemical measurements show that metal complexes undergo quasi‐reversible one‐electron redox processes. The voltammetric results also revealed that the CuL complex has the highest electron transfer rate indicating that both the Cu(II) and Cu(I) forms appear in a similar planar configuration, so the electron transfer does not require larger reorganization of the complex.
A Novel Chemoselective Reaction of Aldehydes with 2‐Mercaptoethanol Catalyzed by SiO2‐NaHSO4 under Solvent‐free Condition
Authors: Azarifar Davood , Forghaniha Ali 
Published: May 2015

AbstractAn efficient and user‐friendly procedure has been developed for the chemoselective protection of aldehyde carbonyl groups such as bis(2‐hydroxyethyl)dithioacetals with 2‐mercaptoethanol catalyzed by silica‐supported sodium bisulphate under solvent‐free conditions. It has been shown that a variety of aldehydes can expeditiously undergo this reaction to produce their corresponding dithioacetals with impressive yields at room temperature.
A Re‐investigation of Low Temperature Photochemistry of 11‐cis‐retinal Mechanism of Photoisomerization
Authors: Yang Lan‐Ying , Liu Robert S. H. 
Published: May 2015

AbstractPhotoisomerization of 11‐cis‐retinal in an organic glass, believed to originate from the 12‐s‐cis con‐former, gives an unstable primary photoproduct(s). The implication of simultaneous single and double bond isomerization is only consistent with an HT mechanism of isomerization. Relation of this isomerization process in the rigid medium of organic glasses with that reported for the same 11‐cis‐retinyl chromophore confined within the binding cavity of rhodopsin (as revealed by reported X‐ray crystal structural study) is discussed.
Effect of Pyrene Additive on the Growth of Gold Nanoparticles in Aqueous Sodium Alkyl Sulfate Micellar Solutions
Authors: Deng Jin‐Pei , Mou Chung‐Yuan 
Published: May 2015

AbstractGold nanoparticles (NPs) were synthesized by chemical reduction in sodium octyl sulfate (SOS), sodium decyl sulfate (SDeS) and sodium dodecyl sulfate (SDS) solutions. Gold NPs prepared in SDS solutions have the smallest size and the highest stability among them. The stability of gold NPs was reflected in the hydrophobic property of the protecting surfactant. Size‐controlled synthesis of gold NPs was further achieved with the addition of pyrene in all surfactant solutions. Experimental results indicated that the combination of SDS and pyrene has the extraordinary effect in decreasing the size and narrowing the dispersity of gold NPs. Micellar electrokinetic capillary chromatography (MEKC) showed that the chemical reaction between pyrene and gold complexes was attributed to the formation of gold NPs inside the micelles at the embryonic stage.
Femtosecond Spectroscopy and Dynamics of the Azulenylosquaric Dye, a Near‐infrared Nonfluorogenic Quencher
Authors: Cheng Yi‐Ming , Wu I‐Che , Lai Chin‐Hung , Pu Shih‐Chieh , Chou Pi‐Tai , Wei Ching‐Yen , Yu Chao‐Ying , Lin Yi‐Hsin , Ting Ching 
Published: May 2015

AbstractAn azulenylosquaric dye (ASQ) has been synthesized to investigate its associated photophysical properties. ASQ is essentially nonluminescent (Φf < 3 × 10−;6) in any solvent despite its very high absorption extinction coefficient (760 nm, ε ˜ 8.2 × 104 M−;1cm−;1 in methanol). Femtosecond fluorescence upconversion, anisotropy kinetics and transient absorption experiments, in combination with the theoretical time‐dependent DFT approach, leads us to conclude that the 760 nm absorption is ascribed to the fully allowed S0 → Sn (n 2) transition. The observed < 130 fs decay component is attributed to the Sn → S1 internal conversion, while the S1 → S0, with a slower radiative decay time (> 233 ns) undergoes a dominant radiationless deactivation process (710 70 fs) possibly governed by strong interaction between S1 and S0 potential energy surfaces.
Organic Electroluminescent Bis(diarylamino) Dibenzofuran Derivatives
Authors: Ku Yu‐Chan , Yen Yung‐Sheng , Huang Tai‐Hsiang , Chen Chih‐Hsin , Lin Jiann T. , Tsai Chii‐Tang 
Published: May 2015

AbstractA new series of 2,8‐disubstituted dibenzofuran derivatives (dbf) have been synthesized via palladium‐catalyzed coupling reactions of 2,8‐diiododibenzofuran and diarylamines. These compounds are amorphous with a glass transition temperature ranging from 65 to 193 °C. The emission colors of the materials vary from blue to bluish green. Two types of double‐layer organic light‐emitting diodes (OLEDs) were fabricated using these compounds as hole‐transporting/emitting layers and TPBI or Alq3 as an electron‐transporting layer: (I) ITO/dbf/TPBI/Mg:Ag and (II) ITO/dbf/Alq3/Mg:Ag (TPBI = 1,3,5‐tris(N‐phenylbenzimidazol‐2‐yl)‐benzene; Alq3 = tris(8‐hydroxyquinoline)aluminum). In general, type I and type II devices have excitons confined in the hole‐transporting and the electron‐transporting layers, respectively. Some blue‐emitting devices of type I have promising performance.
Polymer Electrolyte Containing Dialkoxyacenes with Oligo(Ethylene Oxide) Side Chains
Authors: Huang Ying‐Pin , Chow Tahsin J. 
Published: May 2015

AbstractA series of polymers with oligo(ethylene oxide) (OEO) side chains containing aromatic moieties were synthesized through ring‐opening metathesis polymerization (ROMP). Their potential usage as electrolytes in secondary lithium batteries was investigated. These polymers, while blended with LiClO4, formed amorphous phase with discrete glass transition temperatures (Tg). The interaction between ethylene oxide and lithium ions were analyzed by differential scanning calorimetry and solid‐state nuclear magnetic resonance spectroscopy. Evidence showed that the OEO side chains coordinated to lithium ions effectively comparable to that which happens in regular poly(ethylene oxide) electrolytes.
Ethylene Polymerization Catalyzed by Diimine‐Palladium(II) Complexes Modified on Silicas
Authors: Lee Jung‐Hua , Liu Shiuh‐Tzung 
Published: May 2015

AbstractBoth mesoporous (MCM‐41) and spherical silica supported palladium‐based diimine catalysts were prepared and their behaviors on ethylene polymerization were studied. The results showed that good catalytic activities could be reached with cocatalyst sodium tetraarylborate. Ethylene polymerization with palladium‐based catalysts in mesoporous silicas (MCM‐41) gave polymers with less branched chains than those obtained with the corresponding homogeneous catalyst.
One‐Pot Synthesis and Photocatalysis of Encapsulated TiO2 in Mesoporous SiO2
Authors: Lee Yang Chuan , Chenga Soofin 
Published: May 2015

AbstractNano TiO2 particles encapsulated in mesoporous SiO2 materials (abbreviated as TiO2/MS) were prepared by incorporating the nano‐sized TiO2 particles in the pore‐directing micelles during the cooperative assembly of silica precursor and surfactant. The materials were characterized with X‐ray powder diffraction (XRD), transmission and scanning electron microcopies (TEM and SEM), N2 sorption, ICP‐MS and UV‐Vis spectroscopy. XRD patterns showed that titania was in the anatase phase. The results of TEM and N2 sorption studies confirmed the deposition of nano‐sized particles inside the mesopores of silica material without destroying their integrity. UV‐Vis spectra showed blue shift of the absorption edge for TiO2/MS relative to bulk anatase. When used as photocatalysts, TiO2/MS showed similar activity as anatase TiO2 in photo‐degradation of phenol. However, lower activity than anatase TiO2 was observed in photo‐degradation of lipase, implying that most of the nano‐sized TiO2 were encapsulated inside the mesopores of silica.
Growth of Ternary WCxNy Thin Films from a Single‐source Precursor, W(NtBu)2(NEt2)2
Authors: Chuang Shiow‐Huey , Chiu Hsin‐Tien , Chou Yi‐Hsuan , Chen Shiou‐Fan 
Published: May 2015

AbstractAn organoimido complex of tungsten, bis(tertbutylimido)bis(diethylamido)tungsten, W(NtBu)2(NEt2)2, is used as a single source precursor to deposit thin films of cubic phase tungsten carbonitride, WCxNy (x: 0.21–0.38, y: 0.62–0.76), by metal‐organic chemical vapor deposition on silicon substrates. In general, the N/W and C/W ratios decreased from 0.76 to 0.62 and 0.38 to 0.21, respectively with increasing the temperature of deposition from 500 to 650 °C. Based on the elemental composition and the composition of the gas phase products, it is proposed that the carbon and nitrogen atoms were incorporated through the activation of the ligands.
Ion‐ and Photo‐Analysis of Metal Chelate Reactions on the Semiconductor Surface
Authors: Chang Che‐Chen , Lung Chien‐Hwa 
Published: May 2015

AbstractThe continuing advances in miniaturization of semiconductor devices have seriously challenged contact technology. This work explored the chemical reaction involved in the bottom‐up formation of metal contacts using a linear atomic metal string chelate for CVD. The adsorption and thermal reaction of a linear dipyridylamino trichromium chelate on the GaN surface were characterized using x‐ray photoelectron spectroscopy, secondary ion mass spectrometry, and thermal programmed desorption. The chelate may react with GaN at 105 K and chemisorb on the substrate surface via bonding of the chromium atom in the central metal chain after its terminal bond was disrupted. The bonding of dipyridylamino ligands to the central metal chain remained intact during chemisorption. The chromium atom string of the chemisorbed species was inclined to the surface. A change in bonding configuration of the chelate took place as the chelate dose to the substrate was increased. The chemisorbed structure was stable on the surface in the substrate temperature range between 110 K and 260 K. Some dipyridylamino ligands may be detached from the chelate at ˜340 K. At a higher substrate temperature of ˜540 K, additional ligands may dissociate, along with the cleavage of the chemical bond in the central metal chain.
Solvolysis of Highly Congested Tertiary Benzylic p‐Nitrobenzoates. Kinetic Probe for Detecting Resonance Contribution of Aryl Moiety to the Cationic Transition State
Authors: Liu Kwang‐Ting , Chin Chien‐Pu , Kuo Mann‐Yan 
Published: May 2015

AbstractThe solvolysis of a series of 1‐aryl‐2,2‐dimethyl‐1‐phenyl‐1‐propyl p‐nitrobenzoates (6a‐6g) in a variety of solvents were studied. Both the single‐parameter Hammett‐Brown equation (Eqn. 1) and the dual‐parameter Yukawa‐Tsuno equation (Eqn. 2) showed excellent linear correlations, although inverse order of k(p‐CF3)/k(m‐CF3) was realized in five different solvent systems. A similar result was also found in 3‐aryl‐2,2,4,4‐tetramethyl‐3‐pentyl p‐nitrobenzoates (5) in 80% acetone. The result of Grunwald‐Winstein type correlation analysis against YBnOPNB or YxBnOPNB showed ambiguity for interpretation. It provides more evidence for the lack of coplanarity between the aryl ring and the sp2 plane at the cationic transition state, and thus an insignificant resonance contribution from the aromatic moiety. A comprehensive collection of published data is tabulated.
Stabilization of DNA Hairpins by Stilbene Capping of the Terminal Base Pair
Authors: Zhang Ligang , Zhu Huihe , Sajimon Meledathu C. , Stütz Jan A. Rojas , Siegmund Karsten , Richert Clemens , Shafirovich Vladimir , Lewis Frederick D. 
Published: May 2015

AbstractThe synthesis and properties of DNA mini‐hairpin conjugates possessing stilbene capping groups have been investigated for two hairpin base sequences with three stilbene capping groups. The two hairpin sequences 5′‐TTTCACCGAAA vs. 5′‐ATTCACCGAAT differ in the orientation of the terminal base pair, the latter forming the more stable hairpin. Conjugation of these hairpins with a 5′‐stilbenecarboxamide capping group significantly increases hairpin stability and reduces the difference in stability observed for the unmodified hairpins. Replacement of the stilbene phenyl by either a pentafluorophenyl or trimethoxy‐phenyl group results in enhanced stability for the first hairpin sequence but not for the second. These differences are attributed to structure‐specific interactions between the substituted stilbene rings with adenine. Quenching of the fluorescence of the pentafluorostilbene in the capped hairpins is attributed to an electron transfer processes. The enhanced fluorescence observed for the stilbene and methoxystilbene hairpin conjugates is indicative of both the absence of electron transfer quenching by adjacent bases and an increase in the barrier for stilbene nonradiative decay via double bond torsion.
Use of a Disposable Modified Carbon Paste Electrode for Liquid Chromatography‐amperometric Detection of Theophylline and Three Metabolites in Human Serum
Authors: Wang Lai‐Hao , Tien Hsien‐Ju , Tai Chun‐Yao 
Published: May 2015

AbstractChemically modified electrodes, constructed by incorporating potassium hexachloroplatinate K2PtCl6 into the graphite power/paraffin oil matrix used to fabricate conventional carbon paste electrodes, were shown to catalyze the electrooxidation of purine compounds including theophylline, 3‐methylxanthine, 1,3‐dimethyluric acid and 1‐methyluric acid; the modifier electrodes display electrocatalytic activity for the oxidation of purines at 170 mV (vs Ag/AgCl) when used as sensing electrodes in amperometric detection following liquid chromatography. The K2PtCl6 electrodes permitted detection of the purines at similar values of applied potential. The limit of detection (LOD) of theophylline, 1‐MUA, 3‐MXT and 1,3‐DMUA were 1.1 ng mL−;1, 3.2 ng mL−;1, 1.0 ng mL−;1 and 11 ng mL−;1, respectively. The calibration graphs were linear for theophylline and metabolites over the range of concentration used (50–3200 ng mL−;1). Theophylline and its metabolites can easily be separated and analyzed in one run using electrochemical sensor chromatography with a methanol — phosphate buffer containing 20 mM di‐potassium hydrogen phosphate (pH 5.50). Serum samples were collected after the oral administration of black tea from human volunteers. Quantitative data for the determination of a micromolar amount of theophylline and its metabolites in serum samples are in agreement with data obtained by HPLC‐UV.
Nucleophilic Substitution of Diethyl 2‐Chloroazulene‐1,3‐dicarboxylate with Alkyl Lithium
Authors: Chen Arh‐Hwang , Yen Hsiu‐Hang , Chen Wen‐Zhang , Hong Zhi‐Xi , Yuan Shou‐Bin , Chen Wen‐Yi 
Published: May 2015

AbstractNucleophilic substitution reactions of diethyl 2‐chloroazulene‐1,3‐dicarboxylate with four alkyl lithiums (methyl lithium, ethyl lithium, n‐propyl lithium and n‐butyl lithium) afforded the major product of ethyl 2‐chloro‐4‐alkylazulene‐1‐carboxylate and some minor products of 2‐chloro‐4‐alkylazulene, 2,4‐dialkylazulene‐1‐carboxylic acid, ethyl 3,4‐dialkylazulene‐1‐carboxylate, diethyl 6‐alkylazulene‐1,3‐dicarboxylate and diethyl 2‐chloro‐5‐alkylazulene‐1,3‐dicarboxylate, respectively. The kinds and the yields of their products were significantly dependent on the kinds of alkyl lithiums, molar ratios of alkyl lithium/substrate and oxidation conditions at room temperature or under reflux. The major product of ethyl 2‐chloro‐4‐alkylazulene‐1‐carboxylate is proposed to be formed via an addition‐elimination mechanism.
Formation of Pyrazole from Reactions of Sydnones with Cyclopentadiene Followed by Dehydrogenation
Authors: Lin Shaw‐Tao , Tien Hsien‐Ju , Ding Mei‐Fang , Chien Jiann‐Shyan 
Published: May 2015

AbstractSydnones can be converted to dihydropyrazoles by reacting with cyclopentadiene. Dehydrogenation of dihydropyrazole to form a pyrazole is strongly dependent on the nature of aryl substituents.
A New Glycosylation Method Based on 8‐Quinolyl Glycosides
Authors: Chang Chih‐Wei , Ho Tse‐Lok 
Published: May 2015

AbstractA synthesis of two 8‐quinolyl glycosides (1a, 2a) and demonstration of their service as glycosyl donors are described. These stable compounds react with various alcohols in the presence of metal salts at 60 °C for 16–48 h to furnish the coupling products in excellent yields (88–96%).
Simultaneous Kinetic‐Spectrophotometric Determination of Hydrazine and its Derivatives by Partial Least Squares and Principle Component Regression Methods
Authors: Karimi Mohammad Ali , Ardakani Mohammad Mazloum , Moradlou Omran , Behjatmanesh‐Ardakani Reza , Banifatemeh Fatemeh 
Published: May 2015

AbstractSimultaneous kinetic‐spectrophotometric determination of a ternary mixture of hydrazine (HZ) and its derivatives by principal component regression (PCR) and partial least squares (PLS) calibration is described. The methods were based on the difference observed in the reduction rate of iron(III) with HZ, thiosemicarbazide (TSCZ) and phenylhydrazine (PHZ) in the presence of 2,2′‐bipyridine (Bpy). The colored complex of [Fe(Bpy)3]2+ was formed in sodium dodecyl sulfate (SDS) as micellar media, and then monitored at 520 nm. The results showed that simultaneous determination of HZ, TSCZ and PHZ could be performed in their concentration ranges of 1.0–70.0, 0.2–6.0 and 0.1–10.0 μg mL−1, respectively. The root mean squares errors of prediction (RMSEP) of HZ, TSCZ and PHZ were 0.719, 0.164 and 0.105 (for PLS) 0.788, 0.166 and 0.993 (for PCR), respectively. Both methods (PCR and PLS) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ, TSCZ and PHZ in water samples.
Vanadium(III) Complexes of Oxygen Donor Ligands; Their Synthesis, Spectral Characterization and Antimicrobial Studies
Authors: Asif Irum , Ali Saqib , Shahzadi Saira , Mahmood Sohail 
Published: May 2015

AbstractA new series of vanadium(III) complexes with oxygen donor ligands have been synthesized and characterized on the basis of elemental analysis, conductance, infra‐red spectroscopy, electronic spectral data and mass spectrometry. Thermal stabilities of the complexes and their kinetics were studied through thermogravimetric analysis. Estimation of vanadium in the complexes is carried out by ICP‐AES. Biological activities of the complexes 2–5, 7 and 8 have also been tested against various bacteria and fungi.
Quantum Theory of ICN Photodissociation: Density Matrices of Photofragments from a Parallel Transition
Authors: Chen Kuo‐Mei , Chen Kuang‐Chien , Yang Tsung‐Hang 
Published: May 2015

AbstractA quantum treatment on ICN photodissociation from an initial parallel transition (Ω′ = 0 ← Ω″ = 0) to 1 the asymptote CN(|)+ I(2P1/2) is presented. Density matrices of both photofragments are derived, and explicit expressions of the state multipoles in terms of the angular momentum coupling coefficients and the rotation‐bending factors have been obtained. The present theoretical framework provides a foundation to study photofragments with non‐null electronic and/or spin angular momenta. To investigate the angular momentum polarizations phenomena, these density matrices can play a prime role in laser‐based detections of state‐selected photofragments.
Electrochemical Behavior and Determination of Hyoscine‐N‐Butylbromide from Pharmaceutical Preparations
Authors: Farhadi Khalil , Karimpour Ahmad 
Published: May 2015

AbstractThe electrooxidation of hyoscine N‐butylbromide (HBB) was investigated by rotating disk electrode voltammetry, cyclic voltammetry and controlled potential coulometry in 0.1 M HNO3 and in 0.1 M tetrabutylammonium perchlorate (TBAP) solutions of acetonitrile at a platinum (Pt) electrode. Based on the results obtained, it is suggested that a bromide ion of HBB was oxidized in one reversible step in aqueous solutions and in two reversible steps in acetonitrile. A differential pulse voltammetric (DPV) method at a Pt electrode was developed for the determination of HBB in the concentration range of 1.0 × 10−6‐1.0 × 10−3 M. The procedure was applied to the determination of HBB in its formulations as well as its recovery from blood serum and urine samples.
Spectrophotometric Determination of Ondansetron Hydrochloride in Pharmaceutical Bulk and Dosage Forms
Authors: Raza Asad , Ijaz Abdul Subhan , Atta‐ur‐Rehman  , Rasheed Uzma 
Published: May 2015

AbstractA rapid, simple and accurate spectrophotometric method is developed for the determination of ondansetron hydrochloride in pure and tablet formulations. The method depends on the charge‐transfer complexation between ondansetron base as n‐electron donor with chloranil as π‐acceptor to give a colored complex, which absorbs maximally at 470 nm. Beer's law is obeyed in the concentration ranges 70–980 μg mL−1 with molar absorptivity of 4.47 × 102 L mole−1 cm−1. The proposed method is precise, accurate and specific for the quantitative determination of drug in bulk and tablet formulations.
Novel Copper(II)‐Selective Membrane Electrode Based on a New Synthesized Schiff Base
Authors: Akhond Morteza , Najafi Mohammad Bagher , Sharghi Hashem , Tashkhourian Javad , Naiemi Hossein 
Published: May 2015

AbstractA PVC membrane electrode for copper(II) ion based on a recently synthesized Schiff base as a suitable ion carrier was constructed. The electrode exhibits a Nernstian slope of 28.3 ± 0.6 mV per decade of Cu2+ over a wide concentration range of 7.0 × 10−6‐2.6 × 10−2 M with a detection limit of 5.0 × 10−6M in the pH range of 4.2–5.8. The response time is about 10s and it can be used for at least 1 month without any considerable divergence in potential. It was successfully applied as an indicator electrode in the potentiometric titration of copper ions.
Kinetic and Spectrophotometric Determination of Thioctic Acid in Bulk and Pharmaceutical Formulations
Authors: Ibrahim F. A. , Ali F. A. , Ahmed S. M. , Tolba M. M. 
Published: May 2015

AbstractThree simple and sensitive spectrophotometric methods were developed for the determination of thioctic acid in bulk and in its pharmaceutical preparations using iron(III) as an oxidizing agent. Method A is based on kinetic investigation of oxidation reaction of the drug with iron(III) and a subsequent chelation of the produced iron(II) with ferricyanide to form prussian blue colored product at room temperature for a fixed time of 15 minutes at 750 nm. Methods B and C are based on oxidation of the studied drug with iron(III). The equivalent iron(II) produced is allowed to react with either o‐phenanthroline or bipyridyl to give colored species measurable at 510, 522 nm, respectively. Regression analysis of Beer‐Lambert plots showed a good correlation in the concentration ranges of 0.4–4 μg/mL with a detection limit of 0.095 μg/mL for method A and 0.5–5 μg/mL with detection limits 0.137 and 0.127 for method B and C, respectively. The three methods were successfully applied for the determination of the drug in its dosage forms. The percentage recoveries were 99.88 ± 1.40, 99.98 ± 1.26 and 100.64 ± 1.07, respectively.