bluuebunny/crossref_metadata_2025 huggingface dataset:
Hula‐Twist. A Stereoselective and Regioselective Photoisomerization Reaction Mechanism
Authors: Liu Robert S. H. , Yang Lan‐Ying , Hirata Cheryl , Liu Jin , Ho Tong‐Ing
Published: May 2015

Hula‐twist is a rapid diabatic process of photoisomerization. It is not volume‐demanding and its stereochemical consequence is simultaneous isomerization of a double and a single bond. Recent new examples include diene, styrene, stilbene, diphenylbutadiene and other derivatives in organic glasses at liquid nitrogen temperature. In systems where two different modes of HT are possible, a high regioselectivity was observed. Possible involvement of the volume‐conserving mechanism of isomerization in primary processes of photosensitive biopigments is discussed.
Quinoxalines Incorporating Triarylamines: Dipolar Electroluminescent Materials with Tunable Emission Characteristics
Authors: Huang Tai‐Hsiang , Whang Wha‐Tzong , Zheng He‐Gen , Lin Jiann T'Suen
Published: May 2015

Dipolar compounds (abbreviated as QuPy) featuring quinoxaline acceptors and diarylamine or triarylamine donors were prepared via palladium‐catalyzed C‐N or C‐C bond formation in good yields. They possess high thermal stability with a high decomposition temperature (Td > 400 °C) and exhibit no crystalline character. The emission colors of the materials vary from green to orange red and are dependent on the nature of the electron‐withdrawing segments and solvents. Two types of double‐layer organic light‐emitting diodes (OLEDs) were constructed using these dipolar compounds as hole‐transporting/emitting layers and TPBI or Alq3 as an electron‐transporting layer: (I) ITO/QuPy/Alq3/Mg: Ag and (II) ITO/QuPy/TPBI/Mg: Ag (TPBI = 1,3,5‐tris(N‐phenylbenzimidazol‐2‐yl)‐benzen; Alq3 = 1,3,5‐tris(N‐phenyl‐benzimidazol‐2‐yl)‐benzene). The recombination zone in most of those devices were confined in the quinoxaline layers. The green to orange colors in these devices correspond well with the film PL of the material used. The relation between the energy levels of the compounds and the performance of the light‐emitting diode are discussed.
Ligand Dissociation Process from Myoglobin Monitored by the Time‐Resolved Volume Change
Authors: Terazima Masahide
Published: May 2015

Molecular volume is a useful property to characterize the conformation and the intermolecular interaction. The time‐resolved transient grating technique allows us to study the time‐development of the molecular volume during protein reactions. Studies on the ligand escaping process of carboxymyoglobin at room temperature in liquid phase from a viewpoint of the time‐resolved volume change are reviewed.
Solvatochromism in Binary Solvent Mixtures by Means of a Penta‐tert‐butyl Pyridinium N‐Phenolate Betaine Dye
Authors: Mehranpour A. M. , Hashemnia S.
Published: May 2015

The solvatochromic behavior of a penta‐tert‐butyl prydinium N‐phenolate betaine dye was studied using UV‐visible spectrophotometry in several binary mixture solvents. The solvent polarity parameter, ET (1) (kcal. mol−1) was calculated from the position of the longest‐wavelength intramolecular charge transfer absorption band of this penta‐tert‐butyl betaine dye.

For binary solvent mixtures, all plots of ET (1) versus the mole fraction of a more polar component are nonlinear owing to preferential solvation of the probe by one component of the binary solvent mixture.

In the computation of ET (1) it was assumed that the two solvents mixed interact to form a common structure with an ET (1) value not always intermediate between those of the two solvents mixed. The results obtained are explained by the strong synergism observed for some of the binary mixtures with strong hydrogen bond donors (HBD) solvents such as alcohols.
Anodic Oxidation Behaviors of Formaldehyde at Boron‐Doped Diamond Electrodes
Authors: Changa Chia‐Chin , Chena Li‐Chia , Liu Shyh‐Jiun , Tien Hsien‐Ju , Chang Hsien‐Chang
Published: May 2015

The electrochemical behaviors of formaldehyde (FA) at boron‐doped diamond (BDD) electrodes are investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear scanning voltammetry (LSV) techniques. The CV results show that the oxidation reaction of FA is influenced by the hydroxyl concentration in the solution, and the peak current response with the FA concentration is linear at the range from 10 to 100 mM. The differential capacitance from EIS results indicate that the FA molecules adsorb at the BDD electrode surface at low potential (from 1.0 to 1.4 V). The kinetic studies have been examined with the various concentrations of FA, pH, and temperature. The activation energy of FA oxidation is also calculated. The results of kinetic study indicate that the adsorption of FA molecules at the BDD electrode is the rate‐determining step at low potential (from 1.0 to 1.40 V).
Synthesis and Mesogenic Properties of Liquid Crystals Containing Terminal Cyclohexylmethanol, Cyclopentylmethanol, Cyclobutylmethanol and Cyclopropylmethanol Moiety
Authors: Chen Jo‐Nan , Hsu Fang‐Ming , Wang Hui‐Chun , Wu Chung‐Wen , Cheng Pao‐Swu , Tsai Wen‐Liang
Published: May 2015

Four series of compounds 11˜50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41, 46, and 20, respectively, which are 75 °C for 41, 115 °C for 46, and 100 °C for 20.
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

A 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

A 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

An 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

Photoisomerization 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

Gold 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

An 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

A 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

A 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

Both 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

Nano 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

An 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

The 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

The 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

The 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

Chemically 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

Nucleophilic 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

Sydnones 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

A 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

Simultaneous 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

A 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

A 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

The 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

A 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

A 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

Three 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.
Spectrofluorimetric Determination of Itraconazole in Dosage Forms and Spiked Human Plasma
Authors: El‐Enany N. , El‐Sherbiny D. , Belala F.
Published: May 2015

A highly sensitive fluorimetric method was developed for the determination of itraconazole in pharmaceutical preparations and biological fluids. The proposed method is based on measuring the native fluorescence intensity of itraconazole in methanol at 380 nm after excitation at 260 nm. The fluorescence intensity‐concentration plot was rectilinear over the range 0.2 to 2.0 μg/mL with a lower detection limit of 0.05 μg/mL (6.52 × 10−11 M). The method was further applied to the determination of itraconazole in capsules and spiked human plasma, the mean % recoveries (n = 4) was 100.37 ± 0.86 and 95.47 ± 2.93, respectively. The mean % recoveries were in agreement with those obtained from a reference method.
Multi‐Channel Surface Acoustic Wave (SAW) Sensor Based on Artificial Back Propagation Neural (BPN) Network and Multivariate Linear Regression Analysis (MLR) for Organic Vapors
Authors: Hsu Hui‐Ping , Shih Jeng‐Shong
Published: May 2015

A six‐channel surface acoustic wave (SAW) detection system with a 315 MHz one‐port quartz resonator and a homemade computer interface for signal acquisition and data processing was developed to detect various organic vapors. The oscillating frequency of the SAW quartz crystal decreased due to the adsorption of organic molecules on the coating materials. Polyethylene glycol, 18 crown 6 (18C6), Cr3+/cryptand‐22, stearic acid, polyvinylpyrrolidene and triphenyl phosphine coated quartz crystals were used as sensors. An artificial back propagation neural (BPN) network was used to recognize various organic gases such as hexane, 1‐hexene, 1‐hexyne, 1‐propanol, propionaldehyde, propionic acid and 1‐propylamine. It showed not only the distinction of unity of organic vapors but also mixtures of gases. The learning rate and the hidden unit of a neural network system for BPN analysis were investigated. Furthermore, the concentrations of these organic vapors were computed with about 10% error by multivariate linear regression analysis (MLR). MLR analysis with a multichannel SAW sensor was applied to determine the concentration of each component in a mixture of 1‐hexene, 1‐hexyne and propionaldehyde.
The Efficiency of a Microcolumn of Rice Bran for On‐line Trace Enrichment in FI‐AAS, a Highly Selective System for On‐line Preconcentration and Determination of Copper
Authors: Dadfarnia S. , Haji Shabani A. M. , Gohari M.
Published: May 2015

A flow injection flame atomic absorption spectrometry system incorporating a microcolumn of rice bran was designed, and its capability for on‐line trace enrichment of copper, cadmium and lead was studied. Analytes were deposited on the microcolumn by processing a standard or solution of analytes on the column. Injection of 250 μL of nitric acid (1 mol/L) then served to elute the retained species to FAAS. The procedure was successfully applied for determination of copper in tap water, well water and multivitamin tablets. The accuracy was assessed through recovery experiments and independent analysis by furnace‐AAS. A sample volume of 20 mL of copper resulted in a preconcentration factor of 96; precision value at the 20 μg/L was 4.1%.
Chemical Constituents from the Roots of Patrinia Rupestris
Authors: Yang Xiu‐Ping , Yuan Cheng‐Shan , Jia Zhong‐Jian
Published: May 2015

Phytochemical investigation of the roots of Patrinia rupestris afforded a new triterpenoid patrirupin A (1) and a new iridoid patrirupin B (2), as well as three known triterpenoids: 3‐oxo‐olean‐12‐en‐28‐oic acid (3), ursolic acid (4), α‐amyrin (5), three known iridoids: isovaltratum (6), 11‐ethoxyviburtinal (7), homobaldrinal (8), five known steroids: ergosterol (9), ergost‐6,22‐diene‐3β,5α,8α‐triol (10), 6‐hydroxenone (11), β‐sitosterol (12), daucosterol (13), and two known flavones: 1‐hydroxy‐5‐methoxy xanthen‐9‐one (14), 3′,4′,5,7‐tetrahydroxyflavanone (15). The new compounds were characterized by means of spectroscopic methods including UV, IR, 1D, 2D NMR and HRESIMS, and the known ones were established on the basis of comparing their NMR data with those of the corresponding compounds in the literature.
Chemical Constituents from the Leaves of Litsea Acutivena
Authors: Tsai Ian‐Lih , Cheng Ming‐Jen , Hung Hsiu‐Wen , Cheng Hsin‐I , Chen Ih‐Sheng
Published: May 2015

Continuous investigation of the CHCl3‐soluble and n‐hexane fractions of the leaves of Litsea acutivena Hayata (Lauraceae) led to the isolation of one new butanolide, acutilactone (1), one new lactone, 4‐nonacosyl‐dihydrofuran‐2‐one (2), together with 15 known compounds. The known compounds included one butanolide, one norisoprenoid, one quinone, two steroids, one triterpenoid, one coumarin, two fatty acids, one amide, and five other compounds. The structures of these compounds were determined by means of spectral analyses.
A Facile Method for Synthesis of 5‐Hydroxypentene via Sonochemical Barbier Reaction
Authors: Lee Adam Shih‐Yuan , Tsao Kuo‐Wei , Chang Yu‐Ting , Chu Shu‐Fang
Published: May 2015

A series of 5‐hydroxypentenes was synthesized from the reaction mixture of Mg powder, 1,2‐dibromoethane, 4‐bromobutene and aldehydes in THF under ultrasound. This sonochemical Barbier reaction provides a simple and alternative method for preparation of 5‐hydroxypentene instead of the allylating reagent with epoxide.
Investigation of the Interaction between N,N′‐Di(4‐Chlorophenyl)Thiourea and Human Serum Albumin by Fluorescence Spectroscopy: Synchronous Fluorescence Determination of Human Serum Albumin
Authors: Cui Feng‐Ling , Wang Jun‐Li , Cui Yan‐Rui , Li Jian‐Ping
Published: May 2015

Under physiological conditions, interaction between N,N′‐di(4‐chlorophenyl)thiourea synthesized and human serum albumin was investigated by using fluorescence spectroscopy and UV absorption spectrum. The intrinsic fluorescence of human serum albumin was quenched by N,N′‐di(4‐chlorophenyl)‐thiourea through a static quenching procedure. The binding constants (K) at 14 °C and 24 °C were obtained, and the values were 2.541 × 105 M−1 and 2.021 × 105 M−1, respectively. Thermodynamic parameter enthalpy change (ΔH) and entropy change (ΔS) were calculated to be ‐16.19 KJ/mol and 47.05 J·mol1·K−1, respectively, which indicated that hydrophobic force played a major role in interaction. The binding distance was evaluated on the basis of the theory of Föster energy transfer. The effects of various metal ions on the binding constants of N,N′‐di(4‐chlorophenyl)thiourea with human serum albumin were studied. A synchronous fluorescence technique for determination of human serum albumin was developed, and the method was successfully applied to the detection of HSA in human serum samples.
Liquid‐Phase Synthesis of 2‐Methyl‐2‐Aryloxypropanoic Acid Derivatives from Polyethylene Glycol) Supported 2‐Bromo‐2‐Methylpropanoate
Authors: Huang Bin , Huang Pei‐Gang , Sheng Shou‐Ri , Wang Qiu‐Ying , Guo Lei , Jiang Shao‐Hua
Published: May 2015

An efficient liquid‐phase synthesis of 2‐methyl‐2‐aryloxypropanoic acid derivatives with good yields and high purity on soluble polyethylene glycol (PEG) has been developed by treatment of PEG‐bound 2‐bromo‐2‐methylpropanoate with phenoxides in the presence of a catalytic amount of NBu4I and KI, and subsequent cleavage from the PEG.
Brilliant Blue R Adsorption from Aqueous Solution on Activated Carbon Produced from Corncob Waste
Authors: Bangash Fazlullah Khan , Alam Sultan
Published: May 2015

Brilliant blue R adsorption from aqueous solution on activated carbon produced from corncob waste was investigated. The carbon samples were characterized by XRD, SEM, EDS and FTIR methods. The surface functional groups (carboxyl, lactone or phenol, ether, hydroxyl) disappeared at high activation temperature, resulting in a high amount of carbon with respect to oxygen. The kinetic studies of the adsorption of brilliant blue R on carbon at 10 and 45 °C showed that the first order and intraparticle diffusion models apply to the data. The reaction rate increased with the increase in temperature of adsorption/activation. Thermodynamic parameters like ΔE#, ΔH# and ΔS# for adsorption were calculated from the kinetic data. The positive value of ΔH# shows the endothermic nature of adsorption which decreased with the increase in adsorption/activation temperature. The negative values of ΔS# reflect a decrease in the disorder of the system at the solid‐solution interface during adsorption. Equilibrium studies showed that the data fits the Langmuir model.
Concise Synthesis and Antimicrobial Activities of New Substituted 5‐Isoxazolpenicillins
Authors: Wang Xi‐Zhao , Jia Jiong , Zhang Yan , Xu Wei‐Ren , Liu Wei , Shi Fang‐Niu , Wang Jian‐Wu
Published: May 2015

The synthesis of a series of new 5‐isoxazolpenicillins is described, which were obtained by coupling substituted isoxazoles with 6‐APA. Concise large‐scale synthesis of 3,5‐disubstituted isoxazoles by 1,3‐dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram‐negative bacteria.
Cyclic Voltammograms of Ferrocene on Multi‐Walled Carbon Nanotubes (MWCNTs)‐Modified Edge Plane Pyrolytic Graphite (EPPG) Electrode in Room Temperature Ionic Liquids (RTILs) of 1‐Ethyl‐3‐Methylimidazolium Tetrafluoroborate (EMIBF4)
Authors: Ding Ke‐Qiang , Wang Qing‐Fei , Zhao Mian
Published: May 2015

In this work, the electrochemical behavior of ferrocene (Fc) was investigated by cyclic voltammetry (CV) in room temperature ionic liquids (RTILs) of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF4) on glass carbon (GC), edge plane pyrolytic graphite (EPPG) and multi‐walled carbon nanotube (MWCNTs)‐modified EPPG electrodes, respectively. The results demonstrated that on GC electrode, pairs of well‐defined reversible peaks were observed, while for the electrode of EPPG, the peak potential separation (ΔEp) is obviously larger than the theoretical value of 59 mV, hinting that the electrode of EPPG is distinguished from the commonly used electrode, consistent with the previous proposition that EPPG has many “defects”. To obtain an improved electrochemical response, multi‐walled carbon nanotubes (MWCNTs) were modified on the electrode of EPPG; the increased peak current and promoted peak potential separation not only proved the existence of “defects” in MWCNTs, but also supported that “creating active points” on an electrode is the main contribution of MWCNTs. Initiating the electrochemical research of Fc on the MWCNTs‐modified EPPG electrode in RTILs and verifying the presence of “defects” on both EPPG and MWCNTs using cyclic voltammograms (CVs) of Fc obtained in RTILs of EMIBF4, is the main contribution of this preliminary work.
Estimation of Residual Nickel and Some Heavy Metals in Vanaspati Ghee
Authors: Khan Hizbullah , Fida Mohammad , Mohammadzai Imdad Ullah , Khan Mumtaz
Published: May 2015

To convert vegetable edible oils into vanaspati ghee, nickel is used as a catalyst in the hydrogenation process. A simple and fast method for the trace level determination of nickel in ghee is reported. In this work different methods were applied for the extraction of residual nickel from ghee samples. Using toluene, benzene and carbon tetrachloride as organic solvents, an acid mixture was used for the extraction of nickel. Extracted nickel was quantified with atomic absorption and colorimetric methods. Among the organic solvents, toluene proved to be the best solvent mediating a 95% extraction of nickel from ghee samples. Nickel was extracted and determined in ten different brands of ghee and in all samples its amount was well above the permissible limit of WHO (0.2 μg/g). Other metals like lead, zinc, copper, and cadmium were also determined and their concentrations were found to be much below the WHO permissible limits.
ZrCl4 as an Efficient Catalyst for Crossed‐Aldol Condensation of Cyclic Ketones with Aromatic Aldehydes in Refluxing Ethanol
Authors: Khodaei Mohammad Mehdi , Bahrami Kiumars , Khedri Mohammad
Published: May 2015

The aldol condensation reaction of cyclic ketones with aromatic aldehydes in ethanol under reflux conditions using ZrCl4 as a catalyst to afford the corresponding α,α′‐bis(substituted benzylidene and cinnamylidene)cycloalkanones in excellent yields has been described. No self‐condensation product was produced.
Semiempirical Molecular Orbital Studies of the Acylation Step in the Lipase‐Catalyzed Ester Hydrolysis
Authors: Zhao Jian‐Hua , Liu Hsuan‐Liang , Lin Hsin‐Yi , Huang Chih‐Hung , Fang Hsu‐Wei , Tsai Shau‐Wei
Published: May 2015

In this study, we present the results from the semiempirical molecular orbital calculations for the acylation step in the lipase‐catalyzed ester hydrolysis. The results reveal that the lowest energy path for the formation of the tetrahedral intermediate is for the serine residue of the catalytic triad to attack the substrate, followed by coupling heavy atom movement and proton transfer. The calculations of four active site models show that the cooperation of the aspartate group and the oxyanion hole is capable of lowering the activation energy by about 16 kcalmol−1. Our results further suggest that the lipase‐catalyzed ester hydrolysis adopts the single proton transfer mechanism.
The Effect of Substituents on the Fluorescent Properties of Para‐Phenylenevinylene
Authors: Ding Liang , Ding Yu‐Qi , Teng Qi‐Wen , Wang Ke
Published: May 2015

Semi‐empirical AM1 method and density function theory were used to study the electronic structures and spectroscopic characteristics of the luminescent material analogous to PPV (para‐phenylenevinylene) oligomers attached to different substituents. It was indicated that the LUMO‐HOMO energy gaps were changed distinctly by means of the electron‐donating effect, conjugated effect and steric effect. The fluorescent wavelength in the fluorescent spectrum, the main absorption peaks in the electronic spectra and the chief bands in the IR spectra for the complexes were red‐shifted, relative to those of the parent molecule, owing to the extension of the conjugated system, the shrink of the energy gap and the weakening of the C=C bonds, respectively. The 13C chemical shifts were also moved obviously when the substituents on the matrix were changed.
An Efficient Method for the Enamination of 1,3‐Dicarbonyl Compounds with Ceric Ammonium Nitrate (CAN)
Authors: Mo Li‐Ping , Liu Shu‐Fen , Li Wan‐Zhi
Published: May 2015

An efficient method for the enamination of 1,3‐dicarbonyl compounds by employing ceric ammonium nitrate (CAN) as the catalyst has been described. A variety of β‐amino‐α,β‐unsaturated ketones and esters have been synthesized in excellent yield within a short reaction time under solvent‐free conditions.
Highly Efficient and Selective Membrane Transport of Silver(I) Using Dibenzodiaza‐15‐Crown‐4 as a Selective Ion Carrier
Authors: Shamsipur Mojtaba , Kazemi Sayed Yhaya
Published: May 2015

A chloroform membrane system containing dibenzodiaza‐15‐crown‐4 was found to be a highly efficient and selective transport of Ag+ ions through a chloroform liquid membrane. In the presence of thiosulfate ion as a suitable ion stripping agent in the receiving phase, the amount of silver transported across the liquid membrane after 105 minis 95 ± 1.3%. The selectivity of Ag+transport from aqueous solutions containing Tl+, Pb2+, Cd2+, Ni2+, Co2+, K+, Ca2+, Sr2+, Hg2+, Zn2+, Cu2+was investigated. The interfering effect of Cu2+ ions was drastically diminished in the presence of EDTA as a proper masking agent in the source phase.
Synthesis and Biological Activity of Mercaptobenzoxazole Based Thiazolidinones and Their Arylidenes
Authors: Kohli P. , Srivastava S. D. , Srivastava S. K.
Published: May 2015

Arylidenes of thiazolidines with mercaptobenzoxazole, namely[(aryl‐4‐oxo‐1,3‐thiazolidin)‐hydrazinoacetyl‐mercaptobenxazole]; (5‐arylidene)‐2‐aryl‐4‐oxo‐1,3‐thiazoliden hydrazinoacetyl‐mercaptobenxazole were synthesized. Their chemical structures have been confirmed by 1H NMR, IR, mass spectra and also by microanalytical data. Antimicrobial evaluation was done by agar dilution method against three pathogenic bacteria viz. Bacillus subtilis, Escherichia coli and Klebsiella pneumoniae and three pathogenic fungi viz. Aspergillus niger, Candida albicans and Fusarium oxysporum. Among new derivatives evaluated, the chloro derivatives exhibited higher potency as compared to the standard drugs streptomycin (for bacteria) and griseofulvin (for fungi) against the tested organisms.
A Clean Synthesis of 1,4‐Diarylquinoline Derivatives Catalyzed by TEBAC in Aqueous Media
Authors: Wang Xiang‐Shan , Zhang Mei‐Mei , Jiang Hong , Shi Da‐Qing , Tu Shu‐Jiang
Published: May 2015

A series of 1,4‐diarylquinoline derivatives were synthesized by the reaction of arylmethylidenemalononitriles or 2‐cyano‐3‐aryl‐1‐acrylate and 3‐arylamino‐5,5‐dimethylcyclohex‐2‐enone in aqueous media at 100 °C catalyzed by TEBAC. Meanwhile, the water medium was chosen as green solvent.
Synthesis of Thiophenes, Azoles and Azines with Potential Biological Activity by Employing the Versatile Heterocyclic Precursor N‐Benzoycyanoacetylhydrazine
Authors: Mohareb Rafat M. , Ho Jonathan Z. , Alfarouk Fatma O.
Published: May 2015

This research work is concerned with the use of N‐benzoyl cyanoacetylhydrazine (3) in synthesizing several new heterocyclic compounds with potential biological activity, via its reaction with various chemical reagents. The synthesized derivatives have actually exhibited, upon screening, antibacterial and antifungal activities.
Spectrophotometric Determination of Acidity Constants of 4‐(2‐Pyridylazo) Resorcinol in Various Micellar Media Solutions
Authors: Ghasemi Jahanbakhsh , Peyman Hossein , Niazi Ali
Published: May 2015

Dissociation equilibria of 4‐(2‐pyridylazo) resorcinol (PAR) in aqueous micellar solutions were determined spectrophotometrically at 25 °C and at the constant ionic strength I = 0.1 M KNO3. For this purpose, the effect of nonionic (Brij‐35, Triton X‐100, Triton X‐114, Triton X‐405), and anionic (SDS) surfactants on the absorption spectra of PAR at different pH values was studied. Results show that the pKa values and pure spectra of each species of PAR are influenced by percentages of a neutral and an anionic surfactant such as Brij‐35, Triton X‐100, Triton X‐114, Triton X‐405 and SDS, respectively, added to the solution of this reagent.