bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of Y(Ba1.5Sr0.5)Cu3Oy with Water
Authors: Lin Ching‐Huang , Kao Huey‐Chuen I.
Published: May 2015

Reaction of superconducting Y(Ba1.5Sr0.5)Cu3Oy (abbreviated as YS‐123) powder with water in a closed system at pH 7 and 25 °C, after 150 h, the concentration ratio of Y:Ba:Sr:Cu ion in the solution is 0.0025:1:0.33:0.0003. Mass equation of the reaction is similar to that of YBa2Cu3Oy (abbreviated as Y‐123). Leaching rate of the Ba ion is higher than that of the Sr ion at the beginning of the reaction, which reflects the basicity difference between these two alkaline earth elements. The initial rate equation is expressed as Ro = k [S]oa [H3O+]ob. [S]o is the initial surface area of YS‐123 powder and H3O+ a catalyst. a and b are found to be 0.99 ± 0.02 and 0.58 ± 0.02, respectively. The initial rate, Ro, for 100.1 mg powder with a mean radius of 0.025 mm at pH 7 and25°C is 1.35 × 10−6 mol·min−1. Rate constant, k, is (0.54 ± 0.03), (1.1 ± 0.1) and (1.90 ± 0.08) × 10−3 mol·min−1·cm−2·M−0.6 for the reaction at 10, 25 and 40 °C, respectively, by using a = 1 and b = 0.6 for calculation. Activation energy (Ea) and pre‐exponential factor (A) calculated from the Arrhenius equation are 31.2 ± 0.4 kJ·mol−1 and (3.0 ± 0.4) × 102 mol·min−1·cm−2·M−0.6. Although the amount of Sr substitution to Ba is only 25%, initial reaction rate of YS‐123 in water is 2 orders magnitude smaller than that of Y‐123 at pH 7.
Constituents from Rubia Ustulata Diels and R. Yunnanensis Diels and Their Antiplatelet Aggregation Activity
Authors: Liou Meei‐Jen , Teng Che‐Ming , Wu Tian‐Shung
Published: May 2015

A new anthraquinone glycoside, rubiayannone‐A (1), and a new coumarin, rubilatin‐A (2), together with twenty‐two known compounds were isolated and characterized from the roots of Rubia ustulata. A new anthraquinone, 2‐carbomethoxyanthraquinone (3), and rubiayannone‐A, 2‐formylanthraquinone were obtained from the roots of R. yunnanensis. The structures of those compounds were elucidated by spectroscopic methods. The antiplatelet aggregation activity of the isolated compounds 1, 4∼6 were also discussed.
Synthesis and Structure Determination of Some New N‐Glycosides of 4,5‐Disubstituted‐1,2,4‐Triazole‐3‐Thiones
Authors: Zamani Khosrow , Faghihi Khalil , Iqbal Rashid
Published: May 2015

Some new N‐glycosides of 4‐(2‐phenylethyl)‐5‐pyridyl‐1,2,4‐triazole‐3‐thiones were synthesised by the coupling reaction of halo sugar with 4,5‐disubstituted 3H‐1,2,4‐triazole‐3‐thiones in the presence of mercuric cyanide and dry nitromethane as solvent, followed by deprotection using dry ammonia in methanol. All of the above compounds were fully characterized by means of infrared, 1H NMR spectroscopy, mass spectroscopy and elemental analysis.
Use of Raman Spectroscopy in Biological Compounds
Authors: Tu Anthony T.
Published: May 2015

The invention and subsequent use of laser as a light source in Raman spectroscopy ignited a wide application of Raman spectroscopy to organic compounds, biological compounds, and to biological tissues. Raman spectroscopy is a vibrational spectroscopy; Raman frequency is related to the mode of various vibrations in a molecule.

In this review article, the use of Raman spectroscopy on biological molecules done at A. T. Tu's laboratory from 1962 to 1998, until his retirement, is summarized. The first part of the article is on peptide backbone structure and the local environment of amino acid residue side chain in proteins, mainly on snake neurotoxins. The second and third parts are direct analyses of gallstones and kidney stones by Raman spectroscopy without extraction, separation, and tedious chemical analysis. The last part is about the use of Raman spectroscopy to determine the anomeric bond in hexapyranosyl compounds.
Progress in the Recent Discovery and Development of Promising Anticancer and Anti‐HIV Agents from Natural Products in the United States
Authors: Wu Jiu‐Hong , Morris‐Natschke Susan L. , Lee Kuo‐Hsiung
Published: May 2015

As the 21st century begins, consumers in all countries are accepting natural medicines to improve quality of life, maintain health, and treat chronic and age‐related diseases. Accordingly, scientists worldwide are increasingly interested in the discovery and development of new drugs from plant, marine, and other sources. Natural resources have become more attractive as potential sources of new medicines, especially to treat cancer and AIDS. Recent progress in these areas will be discussed with emphasis on the discovery and development of clinically useful compounds as well as candidates for clinical trials. Contributions in these areas from the authors' laboratory will also be included.
Electroanalytical Kinetic and Diffusion Studies for the Reduction of 4‐Cyano‐3‐substituted Sydnones
Authors: Wang Lai‐Hao , Tien Hsien‐Ju
Published: May 2015

The electrochemical reduction mechanism of five 4‐cyano‐3‐substituted sydnones was investigated at a hanging mercury drop electrode by cyclic, linear sweep and differential pulse voltammetric methods in Britton‐Robinson buffer (pH 1.68–11.76). The electrode kinetics of 4‐cyano‐3‐(p‐tolyl)sydnone were studied in protic and aprotic solvent containing different tetra‐alkylammonium salts supporting electrolytes, respectively.
Time‐Resolved Thermal Lensing Studies on Metastable Species
Authors: Cheng Chung‐Chih , Wu Guo‐Ray , Chiou Chau‐Shuen , Yu Jen‐Kan , Chou Pi‐Tai
Published: May 2015

Time‐resolved thermal lensing (TRTL) techniques have been applied to resolve photophysical and thermodynamic parameters for various metastable species, of which the relaxation dynamics are dominated by the radiationless transition. Using 1H‐phenalen‐1‐one as a sensitizer, the lifetime (τΔ), absolute quantum yield (ΦΔ) and efficiency of generation (STΔ) of singlet molecular oxygen (1Δg) have been determined in various organic solvents. In particular, through the development of an ultrasensitive detecting system, TRTL studies on the relaxation dynamics of O2(1Δg) become feasible in aqueous solution. In another application, based on the TRTL technique in combination with the O2 sensitization experiment, the T1‐S0 energy gap of the proton‐transfer tautomer in 3‐hydroxyflavone, which is otherwise inaccessible due to the dominant radiationless deactivation, has been deduced to be ∼ 8500 ± 1020 cm−1.
Enhancement of Chemiluminescence from the Oxidation of Luminol with Hydrogen Peroxide Catalyzed by Mn(III)‐Microperoxidase 8
Authors: Yeh Hui‐Chun , Lin Wann‐Yin
Published: May 2015

Mn(III)‐containing microperoxidase 8 (Mn(III)‐MP8) is an effective catalyst for the cheminluminescent (CL) reaction involving the oxidation of luminol with hydrogen peroxide at high pH. The CL emission was dramatically enhanced by the presence of guanidine hydrochloride or sodium carbonate in the reaction mixture. The enhancement was strongly pH‐dependent, with the most prominent pH at 10. Kinetic studies of the CL reaction have revealed that the enhancement was caused primarily by the significant acceleration of the CL cycle by the enhancer. The CL signal covers several orders of magnitude over a wide concentration range of luminol and hydrogen peroxide. The intense CL of the [Mn(III)‐MP8]‐luminol‐H2O2 system, especially in the presence of the enhancer, will have a great potential for extremely sensitive CL assays.
A Simple and Efficient Esterification Method
Authors: Chen Ming‐Yi , Lee Adam Shih‐Yuan
Published: May 2015

A convenient and practical esterification was realized and this reaction proceeded without a dehydrating reagent or water removal equipment. The synthesis of esters by reaction of carboxylic acids with various alcohols such as methyl, ethyl, isopropyl, isobutyl, allyl, benzyl, propargyl and decanyl alcohols were achieved with a catalytic amount of CBr4 under refluxing reaction conditions.
Synthesis and Characterization of Organosoluble Copolyimides Based on 3,3′,4,4′‐Diphenylsulfonetetracarboxylic Dianhydride and a Pair of Aromatic Diamines Containing 1,2‐Bis(4‐Aminophenoxy)‐4‐tert‐Butylbenzene
Authors: Yang Chin‐Ping , Chen Ruei‐Shin , Wang Ming‐Jui
Published: May 2015

A series of copolyimides was synthesized from commercial 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride with a pair of diamines, which contained 1,2‐bis(4‐aminophenoxy)‐4‐tert‐butylbenzene. The intermediate poly(amic acid)s had the inherent viscosities of 0.52–1.52 dL/g and were thermally converted into copolyimides. These copolymers were soluble in a variety of organic solvents such as NMP, DMAc, and DMF, and almost all of them could even be dissolved in less polar solvents such as m‐cresol, pyridine, and dioxane, showing a better solubility than corresponding homopolymers. Copolyimide films had tensile strengths of 87–160 MPa, elongations at a break of 9–12%, and initial moduli of 1.9–2.2 GPa. The glass transition temperatures of these copolymers were in the range of 262–288 °C, lower than that of homopolymers. The copolyimides had 10% weight loss temperatures in the range of 495–522 °C under nitrogen and 508–521 °C under air atmosphere, and they left more than 43% residue even at 800 °C in nitrogen. The thermal stability of copolymers was somewhat sacrificed due to the copolymerization, but they still belong under heat‐resistant polymeric materials.
Photochemical Synthesis of 2,2′‐Biflavanones from Flavone
Authors: Chen Arh‐Hwang , Kuo Wei‐Bao , Chen Chia‐Wen
Published: May 2015

Photolysis of flavone (4) with the electron‐donating amines including triethylamine or 2‐(N,N‐dimethylamino)ethanol in acetonitrile, benzene or methylene dichloride can easily afford two hydrodimers of 2,2′‐biflavanone(racemate) (5a) and 2,2′‐biflavanone(meso) (5b) and one reductive product of flavanone (6). Their yields were dependent on the molar ratios of substrate to amine, the kinds of amines, the solvents used and the irradiation sources. Higher yields were afforded 2,2′‐biflavanone(racemate) (5a), 2,2′‐biflavanone(meso) (5b) and flavanone (6) (30.0%, 20.9% and 15.8%, respectively) in the reaction condition of 1/2 molar ratio of flavone (4) to triethylamine in acetontrile with fourteen hours of irradiation.
Cytotoxic Constituents of the Leaves of Calocedrus Formosana
Authors: Chiang Yi‐Ming , Liu Han‐Kang , Lo Jir‐Mehng , Chien Shih‐Chang , Chan Yih‐Fwu , Lee Tzong‐Huei , Su Jen‐Kuan , Kuo Yueh‐Hsiung
Published: May 2015

The isolation and identification of twenty‐seven components from the leaves of Calocedrus formosana are described. Their structures were determined on the basis of spectral data as well as direct comparison with authentic samples. These compounds include a mixture of fatty acids, five benzenoids, two lignans, one sesquiterpene, fifteen diterpenoids, one steroid and two phaeophorbides. Some of these compounds exhibited cytotoxic activity.
Bromelain Catalyzed Synthesis of Peptides in Organic Solvent
Authors: Tai Dar‐Fu , Fu Shu‐Lin
Published: May 2015

For the first time, immobilized bromelain was shown to maintain high catalytic activity in organic solvent and to form peptide bonds. It requires only 7 hours to obtain Cbz‐Gly‐l‐Leu‐OMe in 85% yield. The precursor of aspartame (Cbz‐l‐Asp‐l‐Phe‐OMe) and other dipeptides were also synthesized by this method.
Novel DNA Binding Agents: Hydrazone‐based Helical Trinuclear Ag Complexes
Authors: Cheng Chien‐Chung , Hung Sue‐Mei , Yeh Chia‐Yi , Chang Chen‐Shen , Wang Wen‐Jwu
Published: May 2015

Using the hydrazone linker and the self‐assembly, functionalized Ag complexes with a helical structure showed a 2.96 Å distance between metal‐metal bonds, well‐aligned aromatic rings, and the strong affinity toward DNA.
Conductimetric Studies of Charge Transfer Complexes of p‐Chloranil with Some Alicyclic Amines in Polar Media
Authors: Sayed Nadia I. Abdel , El Badry Karima , Mohsen Hassan M. Abdel
Published: May 2015

The stoichiometry of charge‐transfer complexes which ionise in polar media has been studied by conductimetric titration technique in the systems morpholine‐p‐chloranil (CA), piperidine‐CA and pyrrolidine‐CA in three different polar solvents namely N,N‐dimethylformamide, acetonitrile and dimethylsulfoxide at different temperatures of 10, 15, 18, 20, 25 and 30 °C. The stoichiometric ratios of these complexes were found to vary from 1:1 to 1:4 (acceptor: donor) depending on the system, temperature and solvent used. The ασM‐values of these complexes have been reported. The effect of solvents, temperatures and types of electron donors on the σP‐values has been examined.
Application of Weakly Oriented Non‐ionic Liquid Crystal Solvents to NMR Studies of Poly‐ethylene Oxide (PEO)
Authors: Liu Pin‐Hsiu , Ding Shangwu
Published: May 2015

We report in this article the application of a series of weakly ordered liquid crystal solvents for liquid state nuclear magnetic resonance (NMR) spectroscopy. The solvents are a n‐alkyl‐poly(ethylene glycol)/n‐alkyl alcohol non‐ionic liquid crystal system, first proposed by Ruckert and Otting (J. Am. Chem. Soc. 2000, 122, 7793). The merits of these solvents are further demonstrated by using them with a homogeneous polymer PEO which is one of the most studied polymer electrolyte materials, thus offering an answer to the question of whether the weak anisotropy introduced by liquid crystal solvents has any connection with the large‐scale (≥ one nanometer) heterogeneity (tertiary or higher orders of structure) of the system under study.
Novel Complex Catalyst of η3‐(Pentamethylcyclopentadienyl)dimethylaluminum/Titanium(IV) Butoxide (Cp*AlMe2/Ti(OBu)4) for Syndiotactic Polystyrene
Authors: Chen Yu‐Pin , Tsai Jing‐Cherng , Hong Jin‐Long
Published: May 2015

A novel metallocene catalyst was prepared from the reaction of (η3‐pentamethylcyclopentadienyl)dimethylaluminum (Cp*AlMe2) and titanium(IV) n‐butoxide Ti(OBu)4. The resulting titanocene Cp*Ti(OBu)3 was combined with methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) to carry out the syndiotactic polymerization of styrene. The resulting syndiotactic polystyrene (sPS) possesses high syndiotacticity according to 13C NMR. Catalytic activity and the molecular weight of the resulting sPSs were discussed in terms of reaction temperature, concentration of MAO, amounts of scavenger TIBA added, and the hydrogen pressure applied during polymerization.
Syntheses, Structures and Spectroscopic Studies of Dimolybdenum Complexes Containing Bridging Butyrate and Phosphine Ligands
Authors: Suen Maw‐Cherng , Chen Jhy‐Der , Keng Tai‐Chiun , Wang Ju‐Chun
Published: May 2015

By reactions of Mo2(O2CPrn)X2(PPh3)2 (X = Cl, 1; X = Br, 2) with Ph2PCH2CH2P(Ph)CH2CH2PPh2 (etp) in CH2X2, the quadruply bonded complexes containing bridging butyrate and tridentate phosphine ligands of the type Mo2(O2CPrn)X3(η3‐etp) (X = Cl, 3; X = Br, 4) were prepared. Their UV‐vis and31P{1H}‐NMR spectra have been recorded and the structures of 1 and 2 have been determined by X‐ray crystallography. Crystal data for 1: space group P21/c, a = 9.708 (2)Å, b = 18.491 (4)Å, c= 12.688 (3)Å, β = 110.76 (3)°, V = 2130 Å3, Z = 2, with final residuals R = 0.0441 and Rw = 0.0519. Crystal data for 2: space group P21/c, a = 9.737 (1)Å, b = 18.632(1)Å, c = 12.680(1)Å, β= 110.27 (1)°,V = 2158.2 (3) Å3, Z = 2, with final residuals R = 0.0322 and Rw = 0.0481. The δ → δ* transition energies, 31P{1H}‐NMR chemical shifts and the coupling constants are dependent on the natures of the halogen atoms and the carboxylate ligands. The through metal‐metal couplings |3JP‐Mo‐Mo‐P| for complexes of the type Mo2(O2CR)X3(η3‐P3), which contain η3‐polydentate phosphine ligands are about 20 ± 2 Hz.
Hydrothermal Alteration of Andesite in Acid Solutions: Experimental Study in 0.05 M H2SO4 Solution at 110 °C
Authors: Fang Jiann‐Neng , Lo Huann‐Jih , Song Sheng‐Rong , Chung San‐Hsiung , Chen Yaw‐Lin , Lin I‐Chieh , Yu Bing‐Sheng , Chen Huei‐Fen , Li Li‐Jun , Liu Chia‐Mei
Published: May 2015

Hydrothermal experiments on an andesite have been carried out under the condition of 110 °C, autogeneous pressure, 0.05 M H2SO4 solution and renewal of acid solution every 6 hours.

The experimental results indicate that the plagioclase and pyroxenes in the treated samples show micropits and microfractures. Small crystals readily suffered from alteration, as compared with large ones, and the susceptibility of the minerals to the acid solution is decreased in the order of plagioclase, augite, hypersthene and opaque minerals. Plagioclase, which is the most reactive mineral in the experiments, shows an increase of SiO2, but a decrease of Al2O3, CaO and Na2O as the experiments proceeded. The chemical change of the treated andesite, it indicates that the relative amounts of SiO2, TiO2, MgO, ΣFeO, MnO and K2O increase, while those of Al2O3, CaO, Na2O and P2O5 decrease with an increase of the experimental duration.

The relative mobility of chemical elements listed in decreasing order is P, Ca, Al, Na, Si, K, Mg, Fe, Mn and Ti in terms of the K value. It is no wonder that Ca, Al and Na are more mobile than others because these elements are readily released into solution from the more reactive plagioclase, while Mg, Fe etc. still stay in the less reactive pyroxenes and opaque minerals.
Rice Bran as an Excellent Sorbent for Heavy Metals from Aqueous Media, 1. Optimization of Conditions
Authors: Farajzadeh Mir Ali , Vardast Mohammad Reza
Published: May 2015

In this two‐part report, the efficiency of rice bran in removal of heavy metals such as cadmium, lead, zinc, nickel, copper and iron(III) from aqueous solution is investigated. The different experimental conditions such as pH, temperature, volume of solution, bran amount, particle size, exchange time, stirring speed, etc. are studied, and the optimum conditions are selected in part 1 of this series of reports. The efficiency of bran in removal of heavy metals is presented with and without treatments. For treatment, heat or acid, alkali and salt solutions were used. The results obtained show that after treating with saturated sodium chloride solution, its efficiency for Ni2+ and Zn2+ improves. At pH 5, all studied cations have recoveries more than 93% (lead and cadmium 100%). The exchange speed is very high and has preference over the classical ion exchangers.
The Facile Reversed‐Phase HPLC Resolution of Tetrahydrofurofuran Nucleus Lignans in Traditional Chinese Medicine: Quantitative Analysis of Asarinin and Sesamin in Asari Radix
Authors: Wang Chao‐Chiun , Chen Shushi , Wu Tian‐Shung
Published: May 2015

Eight tetrahydrofurofuran nucleus lignans: syringaresinol, epi‐syringaresinol, lirioresinol‐B dimethyl ether, xanthoxylol, phillygenin, fargesin, sesamin and asarinin are separated on a C18 column in the reversed‐phase mode. These lignans are plant products formed primarily by the carbon‐carbon coupling of derivatives of cinnamyl alcohol units, in which the two units may be linked by an oxygen bridge to form a tetrahydrofurofuran nucleus and are found to be highly similar in structure. However, these lignans can be baseline resolved under gradient elution in less than 25 minutes. The resolution also can be optimized through altering the flow rate in an isocratic elution. This method is proven to be facile and reliable in routine quantitative analysis of ingredients such as asarinin and sesamin in traditional Chinese medicine Asarum sieboldii. The corresponding recoveries (%) were found to be 95.65 and 96.14, respectively.
Microwave Promoted and Improved Thermal Synthesis of Spiro[Indole‐Pyranobenzopyrans] and Spiro[Indole‐Pyranoimidazoles]
Authors: Dandia Anshu , Singh Ruby , Sachdeva Harshita , Gupta Rajive , Paul Satya
Published: May 2015

Spiro[indole‐pyranoimidazoles] (5) and spiro[indole‐pyranobenzopyrans] (6) are readily synthesized in one step in 86–92 and 91–97% yields by the Michael condensation of 3‐dicyanomethylene‐2H‐indol‐2‐ones (2) with 1‐phenyl‐2‐thiohydantoin (3) and 4‐hydroxy‐2H‐1‐benzopyran‐2‐one (4), respectively, without using any catalyst under different reaction conditions (conventional heating and microwave irradiation using (a) polar solvents (b) neutral alumina/silica gel as inorganic solid support in solvent free conditions). 2 was synthesized in situ by the Knoevenagel condensation of indole‐2,3‐dione (1) and malononitrile in the absence of any catalyst.

100% conversion was observed in most cases on TLC which also showed the formation of a single product. The comparison between the various methods is established.
A Novel Quantitative Structure‐Biodegradability Relationship (QSBR) of Substituted Benzenes Based on MHDV Descriptor
Authors: Liu Yan , Liu Shu‐Shen , Cui Shi‐Hai , Cai Shao‐Xi
Published: May 2015

The molecular holographic distance vector (MHDV) is employed to characterize the structures of 51 substituted benzenes. 29 descriptors from 91 MHDV ones have nonzero values where 3 descriptors have only one nonzero sample and 1 descriptor only two nonzero samples. A genetic algorithm is used to select an optimal combination of the variables from the remaining 25 nonzero descriptors. Then the optimal descriptors are employed to relate to the relative biodegradability using multiple linear regression method. The 6‐variable linear model developed has high quality where the correlation coefficient of estimations and the root mean square error of estimations are 0.9604 and 0.280, respectively, and the correlation coefficient of predictions and the root mean square error of predictions for leave‐one‐out procedure are 0.9471 and 0.324, respectively.
Determination of Thallium by Starch Iodide Method and Its Applications in Environmental Samples
Authors: Asthana Anupama , Pillai Ajai , Gupta V. K.
Published: May 2015

The present method for determination of thallium involves the oxidation of Tl(I) to Tl(III), with bromine water and liberation of iodine by Tl(III) from potassium iodide in acidic medium. The liberated iodine is reacted with starch to form a blue coloured complex having λmax 575 nm. The system obeys Beer's law in the range of 1–10 μg per 25 mL. The molar absorptivity and Sandell's sensitivity were found to be 1.98 × 105 l mol−1 cm−1 and 0.00098 μg cm−2, respectively. The method has been successfully applied for the determination of thallium in water, industrial effluent, flue dust and biological samples.
Steroids and Flavonoids from Polygonum nodosum pers
Authors: Shen Tong , Jia Zhongjian , Zheng Shangzhen , Shen Xuwei
Published: May 2015

Two new steroids Zhonghualiaoine I (1) and Zhonghualiaoine II (2) were isolated along with seven known compounds from Polygonum nodosum pers (Chinese name “Zhonghualiao”, Berberidaceae). Their structures were deduced on the basis of spectral data.
Routes to Pyrazolo[3,4‐e][1,4]thiazepine, Pyrazolo[1,5‐a]pyrimidine and Pyrazole Derivatives
Authors: Elmaati Tarek M. Abu , El‐Taweel Fathi M. A.
Published: May 2015

5‐Aminopyrazole 1 was condensed with aryl aldehydes to give the 4‐arylidenes 2. Compound 2 reacted with thioglycolic acid and ethyl cyanoacetate to give the pyrazolothiazepines 3 and pyrazolopyrimidines 4, respectively. Diazotized 2a coupled with resorcinol to give the pyrazole derivative 5a. Reaction of 1a with β‐keto esters 7, 8 and acetoacetanilides 13 afforded the pyrazolopyrimidines 11, 12 and 15, respectively. Condensation of 1a with 2‐acetylindan‐1,3‐dione 16 yielded fused pyrazolopyrimidine 18. Compound 1a also reacted with the enaminonitriles 19 and 22 to give the pyrazolopyrimidine 20 and 24, respectively.
Inhibitory Kinetic‐Fluorimetric Determination of Trace Aniline
Authors: Cheng Ding‐Xi , Zhang Hong‐Wu
Published: May 2015

A novel inhibitory kinetic‐fluorimetric method is reported for the determination of trace aniline. The method is based on the inhibitory effect of aniline on the oxidation of rhodamine B by potassium iodate in hydrochloric acid. The detection limit for aniline is 0.872 ng/mL; the linear range of determination is 4.10∼41.0 ng/mL. Every parameter has been optimized. Some ions which seriously interfere with the determination can be removed by means of pre‐distillation in basic condition. The proposed method is simple, rapid and reliable. It has been applied to the determination of trace aniline in waste and tap waters.
Interaction of the Anticancer Drug 8‐Azaguanine with DNA
Authors: Ye Bao‐Xian , Wang Cui‐Hong , Jing Ai‐Hua
Published: May 2015

The interaction of 8‐Azaguanine and fish tests double‐stranded DNA (dsDNA) and fish tests single‐stranded DNA (ssDNA) was studied electrochemically by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) at wax‐marinated graphite electrodes (GE) in a 0.2 mol/L acetate buffer (pH 3.6). Different effect factors, such as pH, time, temperature, and DNA concentration were determined. It was observed that the peak current decreased and the peak potential shifted positively with the increasing of time, temperature and DNA concentration, respectively. In addition, the peak current was a linear relationship with DNA concentration in the range of 1 μg/mL ∼ 7 μg/mL. Furthermore, the signals were found to decrease in the order of 8‐AG, 8‐AG‐dsDNA adduct and 8‐AG‐ssDNA adduct, and the signal at a bare electrode was higher than that at the dsDNA‐modified CE. Simultaneously, the electrode reaction process was investigated in detail by some electrochemistry techniques and its dynamics parameters were obtained.
A Detailed Theoretical Study of TiC(001) Relaxed Surface
Authors: Zhang Y. F. , Li J. Q.
Published: May 2015

The geometric and electronic structures of clean TiC(001) surface were investigated using first principles calculations based on generalized gradient approximation density functional theory. The structural optimization of the surface shows that the C and Ti atoms on the top layer move outward and inward, respectively. The results of the band structure calculation indicate that the “active” surface states of TiC(001) surface located around 2.3 eV below Fermi level are originated from 2pz orbital of surface C atoms. Furthermore, the influence of the surface relaxation on the electronic structures, including the charge densities, work functions and surface core level shifts are also discussed in the paper.
A DFT/B3LYP Computational Study of Boron‐Nitride Nanotubes
Authors: Dai Bai‐Qing , Zhang Gui‐Ling , Zhao Jing‐Xiang
Published: May 2015

DFT/B3LYP calculations were carried out for a boron‐nitride nanotube (BNNT) of zigzag (N,0) and armchair (N,N), where N = 4,5 and 6, respectively. From a calculated energy band, density of state and bond order, the electroconductivity and bonding character of BNNT were discussed and compared with that of a carbon nanotube (CNT).
Comparison of Different Polarization Schemes in Open‐shell Relativistic Density Functional Calculations
Authors: Wang Fan , Liu Wenjian
Published: May 2015

It is well established that, in addition to the electron density, the spin density has to be used as a basic variable in open‐shell nonrelativistic density functional calculations. This scheme can easily be extended to scalar relativistic density functional theory, since spin symmetry is retained. However, when spin‐orbit coupling is taken into account, an ambiguity arises on how to define a proper “spin density” in four‐ and two‐component open‐shell relativistic density functional calculations, because spin is no longer a good quantum number. In this context, three conceptually different polarization schemes, viz. Kramers‐unrestricted, collinear, and noncollinear, have been proposed. Systematic comparisons are necessary to reveal their performance. Based on four‐component relativistic density functional calculations performed with the BDF program package for the whole p‐block elements, it is shown that the collinear approach should not be used, since it does not provide any conceptual or computational advantages. The Kramers‐unrestricted scheme should instead be used as a replacement. For cases where the magnitude of spin‐orbit coupling is either very small or very large, the Kramers‐unrestricted and noncollinear approaches are very similar to each other. For other cases where there is a strong interplay between exchange and spin‐orbit coupling, they may differ by 0.1 to 0.2 eV. This can be ascribed either to symmetry breaking in the noncollinear approach or to account for more exchange in the Kramers‐unrestricted scheme. For systems with more than one open subshell, the Kramers‐unrestricted scheme is favored due to its maintenance of symmetry (equivalence) and computational ease.
Density Functional Theory Studies of Adsorption and Vibrational Spectra of Hydrogen on the Rh(111) Surface
Authors: Lai Wenzhen , Xiao Haiyan , Xie Daiqian
Published: May 2015

Density functional theory calculations have been carried out for hydrogen adsorption on an Rh(111) surface for three surface cells (2 × 2), (√3 × √3) and (1 × 1). Geometrical structures were optimized to determine the chemisorption energies. The diffusion barriers and vibrational frequencies for hydrogen adsorbed on Rh(111) have also been evaluated. The 3‐fold hollow site was found to be the most stable site. The effect of surface relaxation was also investigated and found to be small. The calculated vibrational frequencies of 80∼105 and 133∼140 meV at the 3‐fold hollow site were attributed to the asymmetric and symmetric stretching modes of H atom, respectively, and in very good agreement with the observed vibrational frequencies of 79∼90 and ∼135 meV.
Density‐Functional‐Theory Calculation of Semiconducting Carbon Nanotubes under an External Electric Field
Authors: Tien Li‐Gan , Liaw Tsong‐Ming , Li Feng‐Yin , Lin Sheng‐Hsien , Lee Ming‐Hsien , Clark Steward
Published: May 2015

We investigate the structure change of semiconducting carbon nanotubes under an external electric field with density functional theory. It is shown that the shape of the nanotube remains cylindrical and the length of the nanotube is also the same, even under a strong electric field. The only change observed is the diameter of the nanotube. It increases along with the increase of the applied electric field.
Experimental and Theoretical Studies of Quantum Beats in Fluorescence
Authors: Chang C. H. , Huang Cheng‐Liang , Ni Chi‐Kung , Dai H. L. , Hayashi M. , Liang K. K. , Kung Andy , Chen I. C. , Lin S. H.
Published: May 2015

The effect of collision on quantum beat is studied theoretically by applying the density matrix method. As an application of this theory, we analyze the experimentally observed quantum beat appearing in the time‐resolved fluorescence profiles of biacetyl. In order to explain complicated fluorescence beating patterns, we present a three‐state model and several important molecular properties are mapped onto this model. We also investigate how quantum beat patterns appear as a function of the number of the triplet states that are involved in the interaction with the singlet state.
Modeling the Binding and Inhibition Mechanism of Nucleotides and Sulfotransferase Using Molecular Docking
Authors: Lin En‐Shyh , Yang Yuh‐Shyong , Yang Jinn‐Moon
Published: May 2015

Phenol sulfotransferase (PST) catalyzes sulfuryl group transfer from adenosine 3′‐phosphate 5′‐phosphosulfate (PAPS) to a variety of nucleophilic acceptors in biological systems. Physiological sulfation by PAPS results in the production of adenosine 3′,5′‐diphosphate (PAP). PAP may become a strong inhibitor or cofactor for the physiological or the transfer reactions, respectively. Several nucleotides other than PAP also serve as substrates, inhibitors or cofactors of PST catalyzed reactions. We are interested in the effects of these nucleotides on the PST catalyzed reactions and their possible physiological significance in biology. Several nucleotide inhibitors (such as adenosine 5′‐diphosphate and adenosine 5′‐triphosphate) of sulfotransferase in physiological reactions have been reported in the literature. However, our data suggests that they are not inhibitors for the transfer reaction or the reverse physiological reaction catalyzed by PST. The aim of this work is to show that the molecular docking analysis can be successfully used to underline the inhibition mechanism of these nucleotides. First, the selected compounds were subjected to a detailed docking analysis, by means of GEMDOCK, a program able to reveal the most likely binding mode for each ligand. By comparing these results with binding sites and binding compounds of the nucleotides with known X‐ray structures, it is possible to highlight the site specificity and the inhibition mechanism of the select compounds. The results obtained by the above algorithm were further confirmed experimentally. In this paper, we show the effect of a variety of nucleotides on the activity of sulfotransferase in different docking conditions.
Structural Symmetry Study of Some Protonated Dimer Systems
Authors: Liao Hsin‐Yi , Chu San‐Yan
Published: May 2015

The protonated water dimer has a symmetric structure 2 in contrast to the asymmetric structure of the protonated ammonia dimer 1. To make a general understanding of factors affecting structural symmetry in these protonated dimer systems, we carried out a systematic theoretical study using the B3LYP/6‐31+G** method on several D‐A‐D systems with D as the electron‐pair donors NH3, H2O, and CO and A as the electron‐pair acceptors H+ and Li+. We found the magnitude of the first bonding energy for the monomer (BE(1)) is decisive for the symmetry of the D‐A‐D system. A larger BE(1) leads to a smaller BE(2), the bonding energy of D‐A with the second donor. This gives rise to a stronger tendency towards asymmetry. The magnitude of BE(1) correlates well with the difference in ionization potential (ΔIP) of the orbitals involved in the D‐A interaction. The donor‐donor distance (RD‐D) also plays an important role for the asymmetry, since it is also capable of modifying the ratio of BE(2)/BE(1). The parameter χ, correlated to system asymmetry, defined as RD‐D/RD‐A is a useful parameter insensitive to the type of the system studied, with RD‐A referring to the bond distance in the monomer.
Theoretical Chemical Study on NO Interaction with Cu
Authors: Zhang Yuan , Sun Yueming , Cao Ainian , Liu Juzheng
Published: May 2015

Results of quantum calculations on the decomposition of NO to N2O in the presence of Cu are reported. Three approaches of NO interacting with Cu and two decomposition channels via cis‐ and trans‐ (NO)2 dimers have been identified. The configuration of NO approaching the Cu atom with N is more stable than the other two configurations. At low temperature, NO is in favor of decomposing to N2O via the trans‐intermediate Min6 in the presence of the Cu atom, because the decomposition activation energy of this channel is only 61.1 kJ/mol at the B3LYP/Lanl2DZ level, and lower than the other decomposition channel's. The potential energy surface (PES) shows that the cis‐intermediate Min8 is highly stabilized both thermodynamically and kinetically at low temperature, and the calculation results also suggest that the N‐O bond is more easily dissociated than the Cu‐O bond in the Min8. Hence, NO decomposition is very different in the gas phase compared with in the presence of Cu.
Theoretical Calculations on Vibrational Frequencies and Absorption Spectra of S1 and S2 States of Pyridine
Authors: Wu De‐Yin , Hayashi Michitoshi , Shiu Ying‐Jen , Liang Kuo‐Kan , Chang Chung‐Hung , Lin Sheng‐Hsien
Published: May 2015

Three harmonic potential‐energy surfaces of 1A1, 1B1, and 1B2 singlet states of pyridine have been obtained by using ab initio method. Geometric properties and force fields of these states have been determined with the complete‐active‐space self‐consistent‐field (CASSCF) theoretical method. Vibrational frequencies of two excited states have been assigned on the basis of the potential energy distribution from normal mode analysis. The resulting properties are used to simulate the experimental absorption spectrum. From the spectral simulation the totally symmetric vibrations with large Huang‐Rhys factors have been identified as ν12 and ν6a modes in the 1B1 state; ν1 and ν12 modes in the 1B2 state, indicating that these modes have strong vibronic coupling between ground and excited states.
Theoretical Study on Intermolecular Interactions of Methyl Azide Dimers
Authors: Xia Qi‐Ying , Xiao He‐Ming , Ju Xue‐Hai , Tan Jin‐Zhi , Gong Xue‐Dong , Ji Guang‐Fu
Published: May 2015

The geometries and electronic structures of methyl azide and its dimers have been calculated by using ab initio method at the HF/6‐311++G** level. The intermolecular interaction energy is calculated with MP2 electron correlation correction, basis set superposition error (BSSE) correction and zero point energy (ZPE) correction. The most stable dimer with binding energy of −10.78 kJ·mol−1 possesses a six‐membered ring with two C‐H···N hydrogen bonds. Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction. Frequency calculations are carried out on each optimized structure, and IR spectra shifts from the monomer to the dimer are discussed. Based on the vibrational analysis, the changes of thermodynamic properties from the monomer to the dimer with the temperature ranging from 200.00 K to 700.00 K have been obtained using the statistical thermodynamic method.
Theoretical Study of the Inter‐ionic Hydrogen Bonding in the GZT Molecular System
Authors: Chen Cheng , Liu Min‐Hsien , Cheng Sou‐Ro , Wu Lung‐Shing
Published: May 2015

Diguanidinium‐5,5′‐azotetrazolate (GZT) is an ionic type high energy compound, which is combined with two guanidinium cations (C(NH2)3+ or defined as G+) and one 5,5′‐azotetrazolate‐2‐anion (ZT2−). The structure of ZT2− is made up of two N4C tetrazole type five‐member rings connected by an azo type (‐N=N‐) linkage. The multi‐nitrogen structure of the compound makes the ZT2− anion in the GZT molecular system a major high‐energy source with the properties of an electron donor. In addition to this, the C(NH2)3+ cation containing H atoms within its NH2 groups behaves like a good charge acceptor not only for the formation of hydrogen bonds but also in regard to the stabilization effect within the whole molecular system. There are four strong inter‐ionic hydrogen bonds in this GZT molecular system combining with the ZT2− anion and the two C(NH2)3+ (or G+) cations. It is impossible to calculate hydrogen bond energy between its ions by a conventional energy difference method because it is difficult to distinguish whether such an energy difference happens simply because of inter‐ionic Coulomb attraction or because of the pure energy of the hydrogen bond. With our newly developed “hydrogen bonding localization analysis methods”, we have successfully calculated the localized hydrogen bond orders and energies of the inter‐ionic hydrogen bonds in the GZT molecular system. When the localized hydrogen bond energy, the bond order, the shortening of the hydrogen bond distance, the elongation of the bond length, and the red shift of stretching frequency of the closely related NH bond are compared in order to determine the hydrogen bonding strength, all the evidence taken together, proves that the four hydrogen bonds in the GZT inter‐ionic molecular system are stronger than most hydrogen bonds existing in all the inter‐molecular and intra‐molecular hydrogen‐bonding problems we have ever considered previously.
Effect of Different Solvent Characteristics on the Proton‐Ligand and Sm+3‐Ligand Formation Constant of Butanamide‐3‐[2‐[(2‐Hydroxyphenyl Methylene) Amino]Ethylimino]N‐Phenyl(BHPAP) in Mixed Solvents
Authors: Eid Mohammed F. , Mahmoud Faten Z.
Published: May 2015

Complexes equilibrium of (BHPAP) with proton and Sm+3 ion has been measured in various mixed aqueous solvents, viz.; methanol‐water, ethanol‐water, acetone‐water and dioxane‐water. Based on potentiometric equilibrium measurements of hydrogen ion concentration at 30 °C, ionic strength 0.1 M KNO3 and in the above various mixed solvents, the values of protonation constant of BHPAP‐Sm+3 complex have been evaluated. The variation of protonation and stability constants with the inverse of dielectric constant or mole fraction of solvent was studied. Application of Fuoss expression and consideration of electrostatic and non‐electrostatic effects are made to explain the above constants.

The solid complexes were isolated for each Pr+3 and Nd+3‐BHPAP. Elemental analysis, conductance, infrared spectra, and electronic spectra for these solutions and TG, DTG and DTA measurements characterized these solids. The ligand behaves towards the metal ion as a dibasic tetradentate ligand.
Synthesis of Pyrano[4,3‐d]pyrimidine Derivative and Its Behaviour towards Nitrogen Nucleophiles and Active Methylenes
Authors: Abdel‐Razik H. H.
Published: May 2015

Pyrano[4,3‐d]pyrimidine derivative 3 was prepared by reaction of chlorocarbonyl isocyanate 1 with enaminonitrile 2.

Compound 3 reacted with nitrogen nucleophiles 4a‐f to afford 2‐substituted pyrido[4,3d]pyrimidine 5–8, pyrimido[i]1,5a‐diaza‐9‐oxafluorene 9 and pyrimido[i]5a‐aza‐9‐thiafluorene 10 derivatives. Also, compound 3 reacted with active methylene compounds 4j to yield pyrimidine derivatives 14–16 which on reaction with EtONa 4k afforded 1,5,7‐triaza‐10‐oxaphenanthrene derivatives 17–19.
Synthesis of 2‐Dihydrooxadiazolinyl Chromones
Authors: Cao Ling‐Hua , Cui Peng‐Yuan
Published: May 2015

Reactions of the substituted 2‐formyl chromones with aroylhydrazines gave corresponding 2‐(aroylhydrazonomethylidyne) chromones. Then 2‐(3′‐acetyl‐5′‐aryl‐2′,3′‐dihydro‐1′,3′,4′‐oxadiazol‐2′‐yl) chromones were prepared by these 2‐(aroylhydrazonomethylidyne) chromones under refluxing with Ac2O. All target compounds were characterized through elemental analysis and IR, 1H NMR, MS.
Free Radical‐Induced and Pd(II) Complexes‐Catalyzed Poly(norbornene) Formation
Authors: Yeh An‐Chi
Published: May 2015

The reactions of norbornene polymerization were catalyzed by Pd(CH3CN)4(BF4)2 (1), AIBN (2), and [{(2,6‐C6H3(iPr)2)N=C(Me)}2Pd(Me)(CH3CN)][BF4] (3) without using methylalumoxane (MAO). These poly(norbornene)s are readily soluble in organic solvents such as toluene, dichloromethane and tetrahydrofuran.

According to the NMR data, the end group of PNA resulting from the AIBN process is found from THF. The PNT resulting from the catalyst (1) shows bi‐models of GPC bands (Mn= 4236 and 66317), two glass transition temperatures (Tg = 72.7 and 201.5 °C), as well as two decomposition temperatures (Td = 337 and 460 °C).
Antiwear, Antiseize and Antioxidising Properties of Operation‐Conservation Oils Modified with Organometal Oil‐Soluble Additives Containing Nitrogen and Oxygen
Authors: Petkov Petko , Dimitrova Milena , Jordanov Dobromir
Published: May 2015

The present work aims at studying the antiwear, antiseize and antioxidising properties of anode‐shielding corrosion inhibitors. The physicochemical properties of the inhibitors and those of the operation‐conservation motor oils modified with them were determined. It was found that these inhibitors improve the antiwear, antiseize and antioxidising properties of the motor oils obtained. Real‐life experiments were carried out with a four‐stroke four‐cylinder engine (“Skoda” Czech Republic) mounted on a 30‐ton fishing barge which uses diesel fuel containing up to 1,4% sulphur. The antiwear and antioxidising properties of the oils obtained were determined, and a probable action mechanism of the complex corrosion inhibitors was suggested.
Langmuir‐Blodgett Films of Alkanethiolate Gold Nanorods
Authors: Lin Chia‐Chen , Chau Lai‐Kwan , Chang Ser‐Sing , Wang C. R. Chris
Published: May 2015

Colloidal multilayers of octadecanethiol‐capped Au nanorods were prepared using the Langmuir‐Blodgett technique. Uniform growth of the films with increasing number of deposition has been observed. Vertical transfer efficiency indicates efficient transfer for immersion of hydrophobic substrates and poor transfer for emersion of such substrates. The vertically transferred film has an order parameter S = 0.027, which suggests that the orientation of the nanorods in the film is somewhat isotropic about the dipping direction. Horizontal transfer of the Langmuir monolayer on Formvar/carbon‐coated Cu grids, however, gave scattered domains of Au nanorods aligned in parallel stacks. Such behavior is probably related to the rigidity of the Langmuir monolayer.
Solid Supported Reaction of Substituted 2‐Oxazoline with Amines under Microwave Irradiation
Authors: Kidwai Mazaahir , Mohan Richa
Published: May 2015

1,2‐Diaryl‐4‐phenylmethylene‐2‐imidazolin‐5‐ones were obtained by the interaction of primary amines with 2‐phenyl‐4‐phenylmethylene‐2‐oxazolin‐5‐one using acidic alumina or montmorillonite K10 clay under microwave irradiation (MWI). The same reaction over basic alumina gave arylamides of α‐arylamido‐β‐arylacrylic acids in good yield. Usage of acidic alumina for cyclization gave better results in comparison with clay. This procedure highlights the versatility of various solid supports.
Ab Initio Study on the Potential Energy Surfaces of B4 Cluster
Authors: Li Qian Shu , Jin Hong Wei
Published: May 2015

The singlet and triplet potential energy surfaces (PES) for the isomerization and dissociation reactions of B4 isomers have been investigated using ab initio methods. Ten B4 isomers have been identified and of these 10 species, 4 have not been reported previously. The singlet rhombic structure 11 is found to be the most stable on the B4 surface, in agreement with the results of previous reports. Several isomerization and dissociation pathways have been found. On the singlet PES, the linear 13b can rearrange to rhombus 11 directly, while 13c rearranges to 11 through two‐step reactions involving a cyclic intermediate. On the triplet PES, the capped triangle structure 32 undergoes ring opening to the linear isomer 33b with a barrier of 34.8 kcal/mol and 44.9 kcal/mol, and the latter undergoes ring closure to the square structure 31 with a barrier of 30.4 kcal/mol and 33.0 kcal/mol at the MP4/6–311+G(3df)//MP2/6–311G(d) and CCSD/aug‐cc‐pVTZ//MP2/6–311G(d) levels of theory, respectively. The direct decomposition of singlet B4 yielding to B3+B is shown to have a large endothermicity of 87.3 kcal/mol (CCSD), and that producing 2B2 to have activation energy of 133.4 kcal/mol (CCSD).
Cyclohexene Reactivity Using Catalysts Containing Pt, Re and PtRe Supported on Na‐ and H‐Mordenite
Authors: Aboul‐Fotouh Sameh M.
Published: May 2015

The reactivity of cyclohexene (CHE) over catalysts containing 0.3 wt% Pt, 0.3 wt% Re or 0.3 wt% Pt + 0.3 wt% Re supported on Na‐ and H‐mordenite has been studied in an atmospheric flow‐type reactor at a temperature range of 100–400 °C, using a flow of hydrogen (20 cm3/min). The catalysts were characterized for acid sites strength‐distribution, using desorption of ammonia in DSC. The acidity of H‐mordenite (HM) is attributed to strong acid sites, whereas the acidity of Na‐mordenite (NaM) is due to weak acid sites which are not involved in the catalytic reaction under study. The catalysts containing HM enhance the reactivity of CHE for isomorization reactions. However, the reactivity of CHE on NaM catalysts enhances only the hydrogenation and dehydrogenation reactions. Pt/HM is the most selective catalyst for isomerization of CHE, whereas Pt/NaM and PtRe/NaM catalysts are the most selective for hydrogenation and dehydrogenation reactions, respectively. The hydroisomorization of CHE seems to depend only on the acidity of the catalysts, whereas both hydrogenation and dehydrogenation reactions were controlled by metallic function of the catalysts.
Studies on the Mass Spectra of Monocyclic N‐Aryl‐δ‐Valerolactams
Authors: Wang Eng‐Chi , Huang Keng‐Shiang , Lin Kuo‐Fan , Chen Shing‐Ming , Wang Li‐Fun
Published: May 2015

The fragmental behavior of some monocyclic N‐aryl‐δ‐valerolactams in EI‐MS was studied. Their molecular ion peak, together with some characteristic fragments such as [M‐29]+, [M‐56]+•, [M‐69]+, and [M‐98]+, were always found in a series of N‐aryl‐δ‐valerolactams in EI‐MS spectra. Furthermore, the mechanism for the interpretation of each fragment is described.
Synthesis of New Fused and Spiro 1,5‐Benzodiazepines
Authors: Khodairy A. , Abdel‐Ghany H. , El‐Sayed A. M. , Salah H.
Published: May 2015

[1,3‐Dihydro‐4‐phenyl(1,5)benzodiazepin‐2‐ylidene]malononitrile 1a was treated with formaline and some different primary amines to give the corresponding pyrimido(1,5)benzodiazepines 2a–d. Treatment of compound 1a with halo reagents yielded the corresponding pyrrolobenzodiazepines 3a,b. The reaction of compound 1a with active methylenes, bidentates, S,S‐ and N,S‐acetals afforded the corresponding spiro(1,5)‐benzodiazepines 4a‐c–8a,b, respectively.