bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diastereoselective Cyclopropanation Utilizing a New Chiral N,O‐Acetals Prepared by Electrochemical Oxidation of Carbamates
Authors: Matsumura Yoshihiro , Asano Tsuyoshi , Nakagiri Takeshi , Onomura Osamu 
Published: May 2015

AbstractA new chiral bicyclic tetrahydropyridine derivative was synthesized from L‐lysine derivatives utilizing electrochemical oxidation as a key step. Allyl alcohols were incorporated into the tetrahydropyridine derivative to afford N,O‐acetals, and the reaction of the resulting N,O‐acetals with a carbenoid, which was generated from Et2Zn and CH2l2, yielded cyclopropanated products in moderate diastereoselectivities.
Crystal Structure and Magnetic Properties of Pyridyl‐Substituted Nitronyl Nitroxides
Authors: Lee Chin‐Jhan , Wei Ho‐Hsiang , Lee Gene‐Hsiang , Wang Yu 
Published: May 2015

AbstractX‐ray crystal structure and cryomagnetic properties of three organic radicals, 2‐(2‐pyridyl)‐4, 4,5,5‐tetramethyl‐4,5‐dihydro‐1‐H‐imidazol‐1‐oxyl‐3‐N‐oxide(NIT‐oPy) 1, 2‐(3‐pyridyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐l‐H‐imidazol‐1‐oxyl‐3‐N‐oxide(NIT‐mPy) 2 and 2‐(6‐methyl‐2‐pyridyl)‐4,4,5,5‐tetramethyl‐4, 5‐dihydro‐1‐H‐imidazol‐1‐oxyl‐3‐N‐oxide(NIT‐6M‐oPy) 3 were investigated. The crystal structures of compounds 1‐3 show the same feature of a P21/c space group of a monoclinic system. Two crystallographically independent molecules were found in the crystals of compounds 1‐3. The temperature dependence of magnetic susceptibility of compounds 1‐3 revealed an intermolecular antiferromagnetic exchange interaction.
The Synthesis and Chemistry of 8‐Substituted Bicyclo[5.1.0]oct‐1(8)‐ene
Authors: Lee Gon‐Ann , Chen Calvin Ping‐Kuang , Chen Mei‐Yun 
Published: May 2015

Abstract8‐Bromobicyclo[5.1.0]oct‐1(8)‐cne (7), an intermediate for the preparation of 8‐substituted bicyclo[5.1.0]oct‐1(8)‐enes, was synthesized by denomination of 1,8,8‐tribromobicyclo[5.1.0]octane (6). Compound 7 underwent bromo‐lithium exchange followed by nucleophilic substitution reactions to generate bicyclo[5.1.0]oct‐1(8)‐ene (5), 8‐methylbicyclo[5.1.0]oct‐1(8)‐ene (10), and 8‐trimethylsilylbicyclo[5.1.0]oct‐1(8)‐ene (11). The bicyclic cyclopropenes 7, 5, 10, and 11 reacted with cyclopentadiene to form adducts 12, 13, 14, and 15, respectively. All of these Diels‐Alder adducts are endo‐exo isomers (endo‐addition from the view of the cyclopropene and exo‐addition from the view of the cyclooctene).
Preparation of 3‐(3′‐,4′‐Hydroxyphenyl)sydnones
Authors: Tien Hsien‐Ju , Yeh Mou‐Yung , Huang Ded‐Shih , Wu Yi‐Lung , Kuo Wen‐Fa , Chang Wen‐Kuen , Chang Jing‐Chyi 
Published: May 2015

Abstract3‐(3′‐,4′‐Hydroxyphenyl)sydnones were prepared by dealkylation of 3‐(3′‐,4′‐alkoxyphenyl)sydnones with concentrated sulfuric acid at room temperature in a range of 59 to 86% yield.
“Sock‐Ball” Chromatographic Separation of High Molecular Weight Fullerenes with Sock‐Shaped Stationary Phase
Authors: Chang Cheng‐Shyong , Tsai Hou‐Jen , Den Tschau‐Gan 
Published: May 2015

AbstractA method for “Sock‐Bail” chromatographic separation of high molecular weight fullerenes is described. A prepared sock‐shaped stationary phase (Sock‐SAF‐phase) was used for HPLC separation of several polycyclic aromatic hydrocarbons (PAHs) and fullerenes. Fullerenes, as ball‐shaped molecules, are much more strongly retained than PAHs on this stationary phase and have the eluted order C50 < C70 < C76 < C78 < C84 in the mobile phase of n‐hexane/dichloromethane (100/0 ∼ 80/20). In contrast, chromatography on the corresponding unmodified silica phase or SC‐3OH‐phase (an intermediate phase of Sock‐SAF‐phase) gave no separation of fullerenes. This fact indicated that the separation of fullerenes on Sock‐SAF‐phase was related to the selective interaction with the sock moiety.
Reactions of (η6‐Arene)tricarbonylchromium Complexes: Hydrogenation, Nitration, and Bromination
Authors: Own Z. Y. 
Published: May 2015

AbstractIn this study, we explore the reactions of coordinated arenes, e.g., hydrogenation, nitration, and bromination, to prepare compounds which are not accessible from conventional organic synthesis. The reaction products formed from reactions with the coordinated and the uncoordinated arenes are compared. The polycyclic aromatic hydrocarbons (PAHs) employed for this study include phenanthrene, methyl‐ and acetyl‐phenanthrene, and benz[a]anthracene (BA), The tricarbonylchromium group demonstrated various characteristics which influence the reactions in this work, such as an electronic effect to deactivate hydrogenation, a steric effect to exhibit, highly positional selective nitration, and a free radical mechanism to direct bromine to attack at the ring coordinated to tricarbonylchromium.
Oxidation‐Induced Structural Alterations and Its Effect on Chaperone Function of Rat Lens α‐Crystallin
Authors: Ho Yuh , Lai Chien‐Lin , Huang Fu‐Yung 
Published: May 2015

AbstractAn ascorbate‐FeCl3‐EDTA‐H2O2 system was used to oxidize rat lens α‐crystallins. Under this oxidative insult, the chaperone activity of α‐crystallin toward γ‐crystallin was shown to decrease significantly, which is quite different from the result reported by Wang and Spector. (Invest. Ophthalmol. Vis. Sci. 1995, 36, 311‐321.) Fluorescence spectroscopy and circular dichroism were employed to characterize the structural changes of oxidized α‐crystallin. It was found that fluorescence intensity of l‐anilinonaphthalene‐8‐sul‐phonate (ANS) bound to oxidized α‐crystallin increased comparing to that bound to normal α‐crystallin, suggesting oxidation causes the exposure of more hydrophobic regions. Further, α‐crystallin's fluorescence intensity in response to tryptophan residues showed a pseudo first order decline. Amino acid analysis of normal versus oxidized α‐crystallin confirmed actual decline in tryptophan levels, showing about 80% of tryptophan being modified after 10‐hour oxidation. Circular dichroism showed both changes in the secondary and tertiary structures of oxidized α‐crystallin, characterized by a large loss of aromatic‐type amino acid interactions and a large loss of β‐sheet structure. In conclusion, modified tryptophan, secondary and tertiary structural changes of α‐crystallin correlate best with the reduction of chaperone function, the curves all showing a linear slope for 10 hours, then plateauing. These results indicate that the decrease of α‐crystallin chaperone activity is attributed to the structural changes.
The Effect of Lithium Ion on the Regioselectivity of Substitution Reactions of Zinc Sulfolenylate
Authors: Chou Ta‐Shue , Chang Chin‐Jyh 
Published: May 2015

AbstractThe addition of lithium cation to zinc sulfolenylates significantly changes the regioselectivity of its reaction toward carbonyl electrophiles. The more lithium salt is added, the more the reactions prefer to take place at the α‐position of the sulfolenylate.
Synthesis and Crystal Structure of (η2‐Olefin)(N‐phenyl‐2,3‐dicarbomethoxy‐7‐azabenzonorbornadiene)Fe(CO)2 Complexes
Authors: Sun Chia‐Hsing , Wu Shiao‐Yu , Liou Lin‐Shu , Wang Ju‐Chun 
Published: May 2015

AbstractThe title compounds 2a‐f were obtained from photochemical substitution of 1 with alkenes as stable solids in moderate yields. X‐ray structure determination of 2c shows a distorted trigonal bipyramidal geometry with two cross iron‐coordinated olefins. Compounds 2a‐f represent a new type of (η2‐monoolefin)2(R3N)Fe(CO)2.
Kinetic and Mechanistic Studies of Intercalation in Lamellar Hosts Using Time‐Resolved X‐Ray Diffraction
Authors: O'Hare Dermot , Evans John S. O. , Price Stephen 
Published: May 2015

AbstractEnergy dispersive X‐ray diffraction (EDXRD) has been used to perform in‐situ kinetic studies on the intercalation of a range of guest molecules in layered lattices. The kinetics of the intercalation of cations {K+, PyH+ (Py = C5H5N), NMe+4} and the long chain ammonium ions C12TMA, C16TMA, C18TMA (C12TMA = dodecyltrimethylammonium, C16TMA = hexadecyltrimethylammonium and C18TMA = octadecyltrimethylammonium) into crystals of MnPS3 have been determined. These reactions are very fast and in some cases novel transient phases are observed. The rate of cobaltocene, Co(η‐C5H5)2, intercalation in layered dichalcogenides ZrS2, 2H‐SnS2, 2H‐SnSe2, 2H‐TaS2, 2H‐NbS3, 1T‐TaS2 and TiS2 has also been investigated. Integrated intensities of the Bragg reflections have been used to determine the extent of reaction, (α), versus time for each of these reactions. A number of kinetic models have been considered, including the Avrami‐Erofeyev (m = 1.5) deceleratory nuclei‐growth model and statistical simulation. The concentration and solvent dependence of the rate of Co(η‐C5H5)2 intercalation into 2H‐SnS2 has also been determined. Surprisingly we find that the rate of intercalation is invariant to the initial Co(η‐C5H5)2 concentration over a wide concentration range.
Novel Water‐Soluble 4,4‐Disubstituted Ruthenium(III)‐Salen Complexes in DNA Stranded Scission
Authors: Cheng Chien‐Chung , Lu Yen‐Ling 
Published: May 2015

AbstractSalen‐type Ru(III) complexes are found to be capable of reacting with physiologically acceptable oxidants. The water solubility and DNA affinity of these Ru(III)‐salen complexes are enhanced by the utilization of a variety of charged groups through the formation of peptide bonds. In the presence of hydrogen peroxide, modified Ru(III)‐salen complexes are capable of nicking DNA. In addition, the reactivity in DNA cleavage increases along with the total number of positive charges retaining in Ru(III)‐salen complexes and less influence in the electronic effect. Using 32P‐end‐labeled oligonucleotides and high resolution polyacrylamide gel electrophoresis, Ru(III)‐salen complexes are found to randomly cleave DNA regardless of the DNA secondary conformation such as bulge, inter‐loop, or double‐stranded regions. The possible reactive species of Ru(III)‐salen complexes in DNA cleavage is considered as the hydroxyl radical and high valent oxoruthenium(IV) species according to the UV titration, quenching studies, and reaction with varied oxidants.
Ene Reaction with Pummerer‐Type Reaction Intermediate of 1‐[(2‐Methylthio)ethanoyl]pyrrolidine: A Novel Synthesis of Trichonine
Authors: Sun Kuo‐Hui , Wang Huey‐Min , Chen Ling‐Ching 
Published: May 2015

AbstractPummerer‐type reaction intermediate 2 of 1‐[(2‐methylthio)ethanoyl]pyrrolidine (1) has been found to react with 1‐alkenes to afford ene adducts 3. Trichonine 4 was synthesized from the adduct 3g.
Meso‐Chloro‐Substituted Indodicarbocyanines: Aggregate Behavior, Electrochemical Properties, Crystal Structure and Photographic Performance
Authors: Dai Zhi‐Fei , Peng Bi‐Xian , Fan Lou‐Zhen , Li Yong‐Fang 
Published: May 2015

AbstractThe correlation of photographic performance of meso‐chloro‐substituted indocarbocyanine dyes having different substituent groups with their electrochemical properties and aggregation behavior in solutions and crystals and on emulsion grains was investigated. The experimental results indicate that the dyes form easily H‐rather than J‐aggregates no matter what they arc on AgBrI emulsions or in solutions and crystals. All the lowest vacant electronic energy level of the dyes, ELV, are much lower than the energy of conduction band of AgBrI (ECB)(‐3.23 ev), so it is very easy for the dyes to trap electrons from the surface of silver halide, leading to strong desensitization by the electron‐trapping process. The desensitization by the dyes depends fundamentally on their amount and structure, especially on the nature of substituents.
Two‐Photon Absorption and Excited‐State Refractions in Anthraquinone Dyes
Authors: Tiao C. J. , Hwang L. C. , Wen T. C. 
Published: May 2015

AbstractWe examine the nonlinear optical properties of solutions of 9,10‐anthraquinone, 1,4‐dihydroxy‐anthraquinone, 5,8‐dichloro‐1,4‐dihydroxy‐anthraquinone and 1,4‐bisethylamino‐anthraquinone by means of the intensity‐dependent transmission and the Z‐scan method with 532 nm 8 ns pulses. The results demonstrated that the 9,10‐anthraquinone displayed a two‐photon absorption (TPA) character. The molecular TPA cross section of this compound is estimated as σ2 = 7.22 × 10−19 cm4/GW or σ2 = 26.96 × 10−48 cm4/photon/s, respectively, and an essential state of ‘m1Ag’, which should be located near the 2ω virtual transition state, is predicted. On the other hand, the effective excited‐state nonlinear refractive coefficients n2eff of these anthraquinones are found to be ∼10−10 esu, which are comparable with those highly conjugated planar molecules of tetrabenzporphyrins and phthalocyanines.
Thermodynamic Studies on the Interaction of Cobalt with Alpha‐Amylase
Authors: Saboury A. A. , Umar Dahot M. , Ghobadi S. , Chamani J. , Moosavi‐Movahedi A. A. 
Published: May 2015

AbstractThe interaction of α‐amylase from Bacillus amyloliquefaciens with divalent cobalt ion was studied by equilibrium dialysis and isothermal titration microcalorimetry methods at 27 °C in neutral solution at pH = 7.0. A new equation with a useful graphical method, very similar to the Scatchard plot was introduced to obtain a dissociation equilibrium constant using microcalorimetric data. The constant is remarkably like that obtained from a normal Scatchard plot, which uses equilibrium dialysis data. The enzyme activity increased significantly with an increasing concentration of cobalt; however, the temperature of denaturation of the enzyme decreased.
Cellulase Activity in Different Buffering Media During Waste Paper Hydrolysis by HPLC
Authors: Cheng Cheanyeh 
Published: May 2015

AbstractThe activity of cellulase has traditionally been described by pH and temperature; however, the buffering medium is also an important factor, Taking plain water as a reference medium, three kinds of buffer including KH2PO4/K5HPO4, citric acid/sodium citrate, and acetic acid/sodium acetate were adopted to survey their effects on the activity of cellulase. Chromatographic assays indicated that xylose, glucose, and cellobiose were the major products and that minor products such as cellotriose and cellotetraose were present in some cases. The activities of cellulase based on glucose production showed that the phosphate buffer acted as a deactivator for cellulase and each of the two organic acid buffers acted as activators for cellulase. The concentration of activation buffer should be high to reach a high cellulase activity; however, this effect would be compensated for by the product inhibition of cellulase. The highest activity obtained was 4.16 ± 0.08 (× 10−3) IU mg−1 for the citric acid/sodium citrate buffer under pH 4.80, 40 °C and an agitation speed of 150 rpm.
Effects of Titania on the Adsorptive and Catalytic Properties of Silica‐Supported Cobalt Catalyst
Authors: Ho Sui‐Wen , Chen Wei‐Ting , Wu Dai‐En 
Published: May 2015

AbstractA series of Ti‐promoted (6 wt%) Co/SiO2 catalysts with titania content of 0 to 10 wt% were sequentially prepared by incipient wetness impregnation, and characterized with X‐ray diffraction, thermogravimetric analysis, chemisorption, temperature‐programmed desorption and infrared spectroscopy. The influences of Ti addition and reduction temperature (400–700 °C) on the adsorptive behavior and the catalytic properties for CO hydrogenation were investigated. The presence of Ti decreases the adsorption capacity of the cobalt surface for H2, but enhances activity per gram cobalt. In addition, the turnover frequency increases 2–4 times upon Ti addition at reduction temperatures of 400–700 °C. The promotion in activity is accompanied by an enhanced selectivity for higher hydrocarbons and olefins. These modifications can be rationalized by the creation of active sites for CO dissociation. The desorption of CO2 at 100 °C during temperature‐programmed desorption of CO indicates the formation of active sites for CO disproportionation. Infrared spectroscopy indicates an increase in the relative absorbance of 2060–2075 cm−1 bands upon Ti addition, which are attributed to CO adsorbed on the defect sites of the cobalt surface. Therefore, the promotion effect of Ti may be directly related to the formation of defect sites on the cobalt surface induced by the decorated titania moieties.
Kinetics of the Base‐Catalysed Isomerization of trans‐meso‐CH3Co(H2O)L2+ (L = 5,7,7,12,14,14‐Hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene)
Authors: Lee Shaoyung , Hung Chia‐Hsi 
Published: May 2015

AbstractThe isomerization of the complex trans‐meso‐CH3Co(H2O)L2+ (L = 5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene) to trans‐primary, rac‐CH3Co(H2O)L2+ has been investigated from pH range 7.11 to 8.09 in aqueous solution. The reaction rate law has been determined as: ‐d[meso‐CH3Co(H2O)L2+]/dt = kOH [OH−][meso‐CH3Co(H2O)L2+], where kOH = 600 ± 10 M−1s−1 at 25 °C and μ = 0.5 M. The activation parameters of the reaction were also studied with ΔH± = 19.1 ± 0.9 Kcal mol−1 and ΔS± = 18.0 ± 0.8 cal K−1mol−1. A mechanism that involves a secondary NH inversion is proposed.
The Constituents from the Leaves of Magnolia coco
Authors: Yu Hsi‐Jung , Chen Chien‐Chih , Shieh Bor‐Jinn 
Published: May 2015

AbstractEighteen compounds including fourteen lignans, one coumarin, and three alkaloids were isolated from the leaves of Magnolia coco. Their structures were established by comparison of spectral data with literature values. Among them, N‐acetylanolobine was elucidated as a new compound.
Determination of Antimony in Sediments by Zeeman‐Corrected Electrothermal Atomic Absorption Spectrometry with Ultrasonic Slurry Sampling
Authors: Mierzwa Jerzy , Sun Yuh‐Chang 
Published: May 2015

AbstractA method was developed for the determination of antimony in slurried sediments (on the basis of samples of three Certified Reference Materials) by electrothermal atomic absorption spectrometry (ETAAS) with Zeeman‐effect background correction. Slurried samples were prepared in 6% nitric acid containing 0.02% of Triton X‐100. A mixed palladium/magnesium chemical matrix modifier, L'vov platform atomization and a temperature‐time program with a relatively short (10 s) sample pyrolysis stage were used.The results of the determinations by this technique are in very close agreement with certified values and the repeatability of this analytical procedure expressed in terms of relative standard deviation was typically better than 9% at the slurry concentration of approx. 90 mg/2 mL. The characteristic mass of Sb (at the spectral line 231.1 nm) was 25.6 pg and the limit of detection (calculated for 100 mg/2 mL slurry) was about 0. 04 μg/g.
The Synthesis of New Type Bisazo Compounds Using 4‐Hydroxy‐2,2,6,6‐Tetramethyl‐l‐Piperidinyloxyl as The Phase‐Transfer Dehydrogenation Catalyst
Authors: Wang Xiao‐Yang , Wang Yu‐Lu , Zhang Zi‐Yi , Li Jian‐Ping , Wang Cai‐Lan 
Published: May 2015

AbstractUsing 4‐hydroxy‐2, 2, 6, 6‐tetramethyl‐l ‐piperidinyloxyl as the phase‐transfer dehydrogenation catalyst to prepare bisazo compounds is reported for the first time. Nine bisaryl carbodiazones were synthesized in high yields under mild conditions. This method was efficient, convenient and rapid. A possible mechanism was suggested by a nitroxide free radical which acted on aryl substituted carbazides to form azo compounds.
New Approaches for Solving Crystal Structures from Powder Diffraction Data
Authors: Harris Kenneth D. M. 
Published: May 2015

AbstractThe determination of crystal structures from single crystal diffraction data can generally be carried out routinely and straightforwardly. However, many crystalline solids can be obtained only as microcrystalline powders and are not suitable for investigation by conventional single crystal diffraction methods. In the past, this problem has limited the ability to elucidate the structural properties of such materials. For the wide range of materials in this category, there is clearly a pressing need to develop and exploit techniques that allow crystal structures to be solved from powder diffraction data. Although traditional techniques for structure solution from powder diffraction data have been applied successfully in several cases, these techniques have certain intrinsic limitations, and for the case of organic molecular crystals the challenges that must be overcome are particularly severe. For these reasons, our recent research has focused on the development and implementation of new methodologies for structure solution from powder diffraction data, leading to new “direct‐space” techniques for structure solution in which a hypersurface based on the profile R‐factor is searched using Monte Carlo or Genetic Algorithm techniques. This paper presents a brief overview of the problems and challenges associated with structure solution from powder diffraction data. The foundations of the techniques that we have developed are described, and illustrative examples (from the field of organic molecular crystals) are given to highlight the application of these techniques.
Cheritamine, A New N‐Fatty Acyl Tryptamine and Other Constituents from the Stems of Annona cherimola
Authors: Chen Chung‐Yi , Chang Fang‐Rong , Teng Che‐Ming , Wu Yang‐Chang 
Published: May 2015

AbstractA new N‐fatty acyl tryptamine, cheritamine (30), along with thirty‐two compounds including nineteen benzenoids, p‐hydroxybenzadehyde (1), p‐hydroxybenzoic acid (2), methylparabene (3), 3‐chlorobenzoic acid (4), vanillin (5), isovanillin (6), vanillic acid (7), isovanillic acid (8), methyl vanillate (9), methyl isovanillate (10), syringaldehyde (11), syringic acid (12), 3,4,5‐trimethoxybenzoic acid (13), trans‐methyl p‐coumarate (14), ferulic acid (15), p‐dihydrocoumaric acid (16), 3‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐1,2‐propanediol (17), 3,4,5‐trimethoxyphenyl‐β‐D‐glucopyranoside (18) and thalictoside (19); one p‐quinone, 2,6‐dimethoxy‐p‐quinone (20); one purine, uridine (21); eight alkaloids, nicotinic acid (22), thalifoline (23), doryphornine (24), (–)‐norstephalagine (25), (‐)‐romucosine (26), (+)‐pronuciferine (27), (+)‐norisocorydine (28) and oxoasimilobine (29) and three steroids, β‐sitosterol‐D‐glucoside (31), stigmasterol‐D‐glucoside (32) and 6′‐(β‐sitosteryl‐3‐O‐β‐glucopyranosidyl)hexadecanoate (33), are isolated from the stems of Annona cherimola. These compounds were characterized and identified by physical and spectral evidence.
A Simple, Efficient and New Method for Preparing N‐Aryl‐2‐Phenyldiazenecarboxamide
Authors: Wang Cailan , Wang Yulu , Wang Xiaoyang , Li Jianping , Wang Hong 
Published: May 2015

AbstractUsing ferric chloride to oxidize aryl substituted semicarbazide for preparing azo compounds has been described for the first time in this paper. Nine azo compounds have been synthesized in a good to excellent yield (≥88%). This method only needs cheap reagents, simple instruments and a short reaction time.
Secolridoids Glycosides from Jasminum amplexicaule
Authors: Shen Ya‐Ching , Lin Tain‐Tsair , Lu Tsung‐Ying , Hung Shu‐Ee , Sheu Jyh‐Horng 
Published: May 2015

AbstractIn addition to jaslanceosides B (1) and E (2), and jasminoside (3), a new secoiridoid glucoside, isojasminoside (4) was isolated from the leaves of Jasminum amplexicaule (Oleaceace). The structure of 4 was determined on the basis of spectral analysis and chemical reactions. Chemotaxonomy for some selected plants in Jasminum is also discussed.