bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective CC Bond Formation to Sulfonylimines through Use of the 2‐Pyridinesulfonyl Group as a Novel Stereocontroller
Authors: Nakamura Shuichi , Nakashima Hiroki , Sugimoto Hideki , Sano Hideaki , Hattori Masataka , Shibata Norio , Toru Takeshi 
Published: December 2007

AbstractEnantioselective CC bond formation to 2‐pyridinesulfonylimines afforded products with good enantioselectivity. Dynamic induction of chirality on the sulfur by coordination of a chiral Lewis acid to the pyridine nitrogen and one of the prochiral sulfonyl oxygens induces enantioselectivity. Since the 2‐pyridinesulfonyl group can easily be removed after the reaction, it acts not only as an activating group but also as an efficient stereocontroller.
Excess Molar Volumes and Viscosities for Binary Mixtures of 1‐Alkoxypropan‐2‐ols with 1‐Butanol, and 2‐Butanol at 298.15 K and Atmospheric Pressure
Authors: PAL Amalendu , GABA Rekha 
Published: December 2007

AbstractExcess molar volumes VmEand kinematic viscosities ν have been measured as a function of composition for binary mixtures of propylene glycol monomethyl ether (1‐methoxy‐2‐propanol), MeOCH2CH(OH)Me, propylene glycol monoethyl ether (1‐ethoxy‐2‐propanol), EtOCH2CH(OH)Me, propylene glycol monopropyl ether (1‐propoxy‐2‐propanol), PrOCH2CH(OH)Me, propylene glycol monobutyl ether (1‐butoxy‐2‐propanol), BuOCH2CH(OH)Me, and propylene glycol tert‐butyl ether (1‐tert‐butoxy‐2‐propanol), t‐BuOCH2CH(OH)Me with 1‐butanol, and 2‐butanol, at 298.15 K and atmospheric pressure. The excess molar volumes are negative across the entire range ofcomposition for all the systems with 1‐butanol, and positive for the systems 2‐butanol+1‐methoxy‐2‐propanol, and +1‐propoxy‐2‐propanol, negative for the systems 2‐butanol+1‐butoxy‐2‐propanol, and change sign for the systems 2‐butanol+1‐ethoxy‐2‐propanol, and +1‐tert‐butoxy‐2‐propanol. From the experimental data, the deviation in dynamic viscosity η from Δxiηi has been calculated. Both excess molar volumes and viscosity deviations have been correlated using a Redlich‐Kister type polynomial equation by the method of least‐squares for the estimation of the binary coefficients and the standard errors.
Distribution and Transfer of Gatifloxacin Between Two Microemulsion Phases with Different Structures in SDS/n‐C5H11OH/H2O System
Authors: CHEN Yuan , GUO Rong 
Published: December 2007

AbstractAt a weight ratio of n‐C5H11OH/H2O=50/50, when the total content of sodium dodecyl sulfate (SDS) was less than 6.0%, the ternary mixture of SDS/n‐C5H11OH/H2O coexisted in two immiscible microemulsions. The distribution and transfer of gatifloxacin (GTFX) between the two phases were studied using UV‐Vis and electrochemistry AC impedance spectra. The results show that GTFX transferred from the upper phase (W/O) to the lower phase (O/W or bicontinuous microemulsion), but a small amount of SDS transferred from the lower phase to the upper phase correspondingly with the increase of the total SDS content at a total GTFX concentration of 1.0×10−5 mol/L. The addition of GTFX did not change the structures of the two different phases fundamentally, but resulted in the transfer and redistribution of GTFX and SDS, so the electric properties of the system were changed correspondingly.
Microcalorimetric Investigation of Influence of Fungicide SYP‐L190 on Growth Metabolism of Tetrahymena thermophila and Bacillus thuringiensis
Authors: LI Hui‐Rong , KU Zong‐Jun , QIN Cai‐Qin , ZHANG Zhong‐Hai , LIU Yi 
Published: December 2007

AbstractFlumorph (SYP‐L190) is a new systemic fungicide with good protective, curative and antisporulant activities but no phytotoxicity to certain plants. Its performance on the environmental ecosystem is unknown. Tetrahymena thermophila and Bacillus thuringiensis are two of biological indicators for the aquatic and soil environmental ecosystem respectively. Microcalorimetric technique based on the heat output was applied to evaluate the influence of fungicide flumorph (SYP‐L190) on the two microorganisms. The thermogenic curves and corresponding thermodynamic and thermokinetic parameters were obtained. SYP‐L190 at a concentration of 50–100 µg·mL−1 had 5% –10% inhibitory ratios aganist Tetrahymena thermophila and was used as a protection reagent, while at a concentration of 100–200 µg·mL−1 SYP‐L190 had 10% –20% inhibitory ratios and was used as a therapy reagent. The metabolic thermogenic curves of Bacillus thuringiensis contained bacterial growth phase and sporulation phase. The SYP‐L190 at a concentration of 0–200 µg·mL−1 had no influence on bacterial growth phase, but led to a little lag of the sporulation phase with a constant heat output. Hormesis was obviously observed in present study.
Synthesis and Kinetic Study on the Chromium(III) Complex [Cr(ASA)(en)2]Cl·2H2O
Authors: LIU Bin , YANG Bin‐Sheng 
Published: December 2007

AbstractIn order to explore the transfer mechanism of chromium(III) in mammals, a novel complex [Cr(ASA)(en)2]Cl· 2H2O, bis(ethylenediamine‐κ2 N,N′)(4‐aminosalicylic acid‐κ2 O,O′) chromium(III) monochloride dihydrate was synthesized (4‐aminosalicylic acid=H2ASA, ethylenediamine=en). The crystal structure belongs to orthorhombic system with the space group P212121 by means of X‐ray diffraction. The characteristic for transfer of Cr3+ from the compound to the low‐molecular‐mass chelator EDTA and the iron‐binding protein apoovotransferrin (apoOTf) was followed by UV‐visible (UV‐Vis) and fluorescence spectra in 0.01 mol·L−1 Hepes at pH 7.4. The second order rate constants were calculated. Those spectra in conjunction were used to obtain more accurate information about the interaction of chromium complex with apoOTf. The experimental results indicate that Cr3+ can be transferred from the complex to apoOTf with the retention of the 4‐aminosalicylic acid acting as a synergistic anion.
Synthesis, Characterization and Activity against Staphylococcus of Metal(II)‐Gatifloxacin Complexes
Authors: LI Ze‐Quan , WU Feng‐Jing , GONG Yun , HU Chang‐We , ZHANG Yun‐Huai , GAN Meng‐Yu 
Published: December 2007

AbstractThree novel isostructural complexes M(gatx)2(H2O)2·4H2O [gatx=gatifloxacin, M=Zn (1), Ni (2) and Co (3)] were synthesized at room temperature and structurally characterized by elemental analysis, IR and single crystal X‐ray diffraction, which exhibit a similar mononuclear structure, in which the metal ion is coordinated by two gatifloxacin and two aqua ligands to furnish a distorted octahedral geometry, and show different activities against staphylococcus due to the different metal ions in the structures.
Study on the Complexation of Molybdenum(VI) with Iminodiacetic Acid and Ethylenediamine‐N,N′‐diacetic Acid by Specific Ion Interaction and Debye‐Hückel Theories
Authors: MAJLESI Kavosh , REZAIENEJAD Saghar 
Published: December 2007

AbstractComplexation of two ligands, iminodiacetic acid and ethylenediamine‐N,N′‐diacetic acid, with molybdenum(VI) was studied in aqueous solutions. Molybdenum(VI) forms a mononuclear complex with the aforementioned ligands of the type MoO3L2−. All measurements have been carried out at 25 °C and different ionic strengths ranging from 0.1 to 1.0 mol·L−1 of NaClO4, with the pH justified to 6.0. Equilibrium concentration products and stoichiometry of the complexes have been determined from a combination of potentiometric and UV spectroscopic measurements. Comparison of the ionic strength effect on these complex formation reactions has been made using a Debye‐Hückel type equation and Bronsted‐Guggenheim‐Scatchard specific ion interaction theory (SIT). Debye‐Hückel theory predicted the first order effects on simple electrolyte solutions. Interactions between the reacting species and the ionic medium were taken into account in the SIT model. All of the calculations have been done by the computer program Excel 2000.
Unprecedented 1D Mixed‐metal Polynuclear Cyclometalated Platinum Complexes: Synthesis, Structural Characterization and Spectroscopic Properties
Authors: CAO Qian‐Yong , GAN Xin , ZHANG Jun‐Feng , CHI Shao‐Ming , LI Hui‐Fangjie , FU Wen‐Fu 
Published: December 2007

AbstractThe complexes [Pt2L2(μ‐dppm)](ClO4)2 (1) and {[Pt2L2(μ‐dppm)Li(CH3CN)2](ClO4)3}n (2), where HL is 6‐[4‐(diethoxyphosphorylmethyl)phenyl]‐2,2′‐bipyridinyl and dppm is bis(diphenylphosphino)methane, have been synthesized and characterized. In complex 1 the platinum(II) center adopts a distorted square planar coordination geometry. The polymer 2 exhibits a "stairstep" configuration with one‐dimensional Pt(II)NˆNˆCPO‐ Li(I)‐OPCˆNˆNPt(II) mixed‐metal units which are linked through dppm. Both complexes have metal‐metal interaction with Pt–Pt distances of 3.325(2) and 3.1432(9) Å, respectively, and display strong metal‐metal‐to‐ligand charge‐transfer (MMLCT) triplet state emission. The density‐functional‐theory calculation was used to interpret the absorption spectra of the complexes.
Development and Validation of Spectrophotometric Methods for the Determination of Cefetamet in Pharmaceutical Dosage Forms
Authors: HIREMATH Basavaraj , MRUTHYUNJAYASWAMY Bennikallu Hire Mathada 
Published: December 2007

AbstractTwo simple and sensitive spectrophotometric methods for the determination of cefetamet in either pure form or in its pharmaceutical formulations were described. The method I is based on the interaction of 3‐methylbenzo[d]‐ thiazolin‐2‐one hydrazone (MBTH) with cefetamet in the presence of freshly prepared ferric chloride in a neutral medium. The resulting blue colored product has λmax at 628 nm. The method II describes the reduction of ferric ion by the drug to ferrous ion followed by a complex formation reaction with 1,10‐phenanthroline (1,10‐phen) to form an orange red colored chromogen exhibiting λmax at 510 nm. The products are stable for more than 5 and 8 h respectively. Common excipients used as additives in pharmaceutical preparations do not interfere in the proposed methods. Both methods are highly reproducible and have been applied to a wide variety of pharmaceutical preparations and the results are comparable with those of official methods.
Selective Detection of Mercury(II) and Copper(II) Based on the Opposite Size‐dependent Fluorescence Quenching of CdTe Quantum Dots
Authors: XIA Yun‐Sheng , CAO Chun , ZHU Chang‐Qing 
Published: December 2007

AbstractThree different size CdTe quantum dots (QDs) capped by 3‐mercaptopropionic acid (MPA) have been prepared in aqueous solutions, and their interactions with Cu2+ and Hg2+ have been investigated. The opposite size‐dependent fluorescence quenching of CdTe QDs by Hg2+ and Cu2+ was observed: Hg2+ quenched smaller particles more efficiently than larger ones while larger particles were more markedly quenched by Cu2+. Based on the different size responses, Hg2+ and Cu2+ were respectively detected with high sensitivity and selectivity, for the first time, using the QDs with different sizes but the same components and capping ligands.
Al2O3/SnO2 Co‐Nanoparticle Modified Grafted Collagen for Improving Thermal Stability and Infrared Emissivity
Authors: CAO Yong , ZHOU Yu‐Ming , SHAN Yun , JU Huang‐Xian , XUE Xue‐Jia 
Published: December 2007

AbstractAl2O3/SnO2 co‐nanoparticles were prepared with a modified sol‐gel technique followed by a thermal treatment process. With these co‐nanoparticles the grafted collagen‐Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X‐ray diffraction, FT‐IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co‐nanoparticles showed a narrow distribution of size between 20–40 nm and could be uniformly absorbed on the tri‐helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co‐nanoparticles with an increase of degradation temperature from 39 to 210 °C and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co‐nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.
Preconcentration and Determination of Chromium Species Using Octadecyl Silica Membrane Disks and Flame Atomic Absorption Spectrometry
Authors: MOGHIMI Ali , SABER‐TEHRANI Mohammad , WAQIF‐HUSAIN Syed , MOHAMMADHOSSEINI Majid 
Published: December 2007

AbstractA novel and selective method for the fast determination of trace amounts of chromium species in water samples has been developed. The procedure is based on the selective formation of chromium diethyldithiocarbamate complexes at different pH in the presence of Mn(II) as an enhancement agent of chromium signals followed by elution with organic eluents and determination by atomic flame absorption spectrometry. The maximum capacity of the employed disks was found to be (396±3) µg and (376±2) µg for Cr(III) and Cr(VI), respectively. The detection limit of the proposed method is 49 and 43 ng·L−1 for Cr(III) and Cr(VI), respectively. The proposed method was successfully applied for determination of chromium species Cr(III) and Cr(VI) in different water samples.
A Concise and Convenient Synthesis of Stilbenes via Benzils and Arylmethyldiphenylphosphine Oxides
Authors: SUN Xun , ZHU Jun , ZHONG Chen , IZUMI Ken‐Ji , ZHANG Chen 
Published: December 2007

AbstractA new and convenient synthetic method has been developed for the construction of stilbenes bearing electron‐withdrawing group(s) by using benzils and arylmethyldiphenylphosphine oxides via sequences involving Wittig‐Horner reaction and a rearrangement in the presence of t‐BuOK in toluene under mild conditions. This approach could be readily applied to a facile synthesis of biologically important natural products, resveratrol and its derivatives, such as trimethoxystilbenes 1 (Z) and 2 (E).
Synthesis of Some N‐Alkoxycarbonyl‐N′′‐benzoyl‐benzamidrazones(p‐toluamidrazones) and 1,3,5‐Trisubstituted 1,2,4‐Triazole Derivatives from N‐Benzoylimidates and their Antimicrobial and Anticancer Screening Studies
Authors: BEKIRCAN Olcay , KAHVECI Bahittin , OZGUMUS Osman Birol 
Published: December 2007

AbstractSome new N‐alkoxycarbonyl‐N′′‐benzoyl‐benzamidrazones (p‐toluamidrazones) 3a–3d, and 1,3,5‐trisubstituted 1,2,4‐triazole 4a–4h derivatives by starting from N‐benzoylbenzimidates or N‐benzoyl‐p‐toluimidates. The structures of compounds 3 and 4 were established on the basis of elemental analyses, IR, 1H NMR, 13C NMR and UV data. Antimicrobial experiments of the compounds performed by using agar‐well diffusion and broth microdilution methods revealed that only compounds 3a–3d, 4a and 4b showed inhibitory effect only on Candida albicans ATCC 60193. However, compound 4b had also specific antibacterial activity against Staphylococcus aureus ATCC 25923. The other compounds showed neither antifungal nor antibacterial activities. Compounds 3a, 4a and 4b have been screened on three human tumor cell lines, breast cancer (MCF7), non small cell lung cancer (NCI‐H460), and CNS cancer (SF‐268) at the National Cancer Institute (NCI), USA, which were found to exhibit low antiproliferative activity.
Synthesis and Nonlinear Optical Properties of a New A‐π‐A Two‐Photon Compound Utilizing Dibenzothiophene as Center
Authors: ZHANG Xian , YU Xiao‐Qiang , YAO Jin‐Shui , JIANG Min‐Hua 
Published: December 2007

AbstractA new two‐photon material, 3E,6E‐bis(2‐pyrid‐4′‐ylvinyl)dibenzothiophene (BPVDBT), has been firstly synthesized by an efficient Pd‐catalyzed Heck coupling route. The single‐ and two‐photon fluorescence, quantum yields, lifetimes, solvent effects of the chromophore were studied in detail and the compound exhibited solvent‐sensitivity. The fluorescence intensity (Iout) and input excitation intensity (Iin) can fit in well with the quadratic parabolas, which indicates that the up‐converted fluorescence was induced by the two‐photon absorption (TPA). TPA cross‐section of BPVDBT has been measured using the two‐photon‐induced fluorescence method, whose value is 14.24×10−50 cm4·s·photon−1·molecule−1 at 750 nm. The experimental results confirm that BPVDBT is a good two‐photon absorbing chromophore with an A‐π‐A type.
Synthesis of Certain 3‐Aminopyrazolo[5,4‐b]pyridine and 3,4‐Substituted Pyrido[2′,3′ :3,4]pyrazolo[5,1‐c][1,2,4]triazine Derivatives
Authors: EL‐LOUH Ali Khader Khalil , ABUNADA Nada Mohamed , EL‐SHOUBAKI Mohamed 
Published: December 2007

Abstract2‐Thioxo‐1,2‐dihydropyridine derivatives 2a, 2b were reacted with methyl iodide to give 2‐methylthiopyridines 3a, 3b, which were reacted with hydrazine hydrate to produce 3‐aminopyrazolo[5,4‐b]pyridines 4a, 4b. Compounds 4a, 4b were diazotized to afford the corresponding diazonium salts 5a, 5b, which were reacted with some active methylene compounds 6a–6h to give the corresponding pyrido[2′,3′:3,4]pyrazole[5,1‐c][1,2,4]triazines 7–14.
Studies on the Refolding of Egg White Lysozyme Denatured by Urea Using "Phase Diagram" Method of Fluorescence
Authors: BIAN Liu‐Jiao , DONG Fa‐Xin , LIANG Chang‐Li , YANG Xiao‐Yan , LIU Li 
Published: December 2007

AbstractThe refolding of reduced and non‐reducing egg white lysozymes in a urea solution was studied by a "phase diagram" method of fluorescence. The result showed that in the refolding of the reduced egg white lysozyme, an intermediate state of an egg white lysozyme exists at the urea concentrations in a final renaturation solution being about 4.5 mol/L, their refolding follows a three‐state model; while in the refolding of the non‐reducing egg white lysozyme, two intermediate states exist at the urea concentrations being separately 4.0 and 2.5 mol/L, and their refolding follows a four‐state model. Through the comparison between the unfolding and refolding of an egg white lysozyme in the urea solution, it was found that both of the refolding of reduced and non‐reducing egg white lysozyme molecules was irreversible to their unfolding in the urea solution. Finally, a suggested refolding was separately presented for the reduced and non‐reducing egg white lysozymes in the urea solution.
The Pharmacophore Hypothesis of Novel Inhibitors for Aurora A Kinase
Authors: WANG Xiao‐Jian , CHEN Ya‐Dong , YANG Qian , YOU Qi‐Dong 
Published: December 2007

AbstractA three‐dimensional pharmacophore model was developed from a series of inhibitors of Aurora A kinase to discover new potent anti‐cancer agents using the HypoGen module in the Catalyst software. The pharmacophore model was developed based on the structure of 20 currently available inhibitors, which were carefully selected from the literature. The best hypothesis (Hypo l) was defined by four features: one hydrogen‐bond donor and three hydrophobic points, with the best correlation coefficient of 0.909, the lowest rms deviation of 1.563, and the highest cost difference of 99.075. The Hypo 1 was then validated by a test set consisting of 24 compounds and by a cross‐validation of 95% confidence level through randomizing the data using the CatScramble program, which suggested that a predictive pharmacophore model had been successfully obtained.
Reaction of 3‐Thioformylindolizines with Tributylphosphine
Authors: LIU Wei‐Wei , LI Na , ZHAO Yue‐Qiang , TANG Li‐Juan , HU Hong‐Wen 
Published: December 2007

Abstract2‐Phenyl‐3‐thioformylindolizine and 1,2‐dimethyl‐3‐thioformylindolizine undergo a novel desulfur coupling reaction in the presence of tributylphosphine to give (E)‐1,2‐bis(3‐indolizinyl)ethenes in high yields. The structures of products were confirmed by IR, 1H NMR, MS, elemental analysis and single crystal X‐ray diffraction analysis. The mechanisms involved in various stages of the reaction were discussed.
A Novel Stereoselective Synthesis of (1Z,3E)‐2‐Phenyl(or p‐Tolyl)sulfonyl‐substituted 1,3‐Dienes via Palladium Catalyzed Cross‐coupling Reactions of (E)‐α‐Iodovinyl Sulfones
Authors: HU Rong‐Hua , CHEN Gui‐Qin , CAI Ming‐Zhong 
Published: December 2007

Abstract(E)‐α‐Stannylvinyl phenyl(or p‐tolyl)sulfones underwent an iododestannylation reaction to afford (E)‐α‐iodovinyl phenyl(or p‐tolyl)sulfones 1, which reacted with (E)‐alkenylzirconium(IV) complexes 2 produced in situ by hydrozirconation of terminal alkynes in the presence of a Pd(PPh3)4 catalyst to afford stereoselectively (1Z,3E)‐2‐ phenyl(or p‐tolyl)sulfonyl‐substituted 1,3‐dienes 3 in good yields.
A Multidisciplinary Approach for the Identification of Novel HIV‐1 Non‐Nucleoside Reverse Transcriptase Inhibitors: S‐DABOCs and DAVPs
Authors: Radi Marco , Falciani Chiara , Contemori Lorenzo , Petricci Elena , Maga Giovanni , Samuele Alberta , Zanoli Samantha , Terrazas Montserrat , Castria Marinunzia , Togninelli Andrea , Esté José A. , Clotet‐Codina Imma , Armand‐Ugón Mercedes , Botta Maurizio 
Published: December 2007

AbstractAmong the FDA approved drugs for the treatment of AIDS, non‐nucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of first‐line anti‐HIV‐1 therapy because of the less‐severe adverse effects associated with NNRTIs administration in comparison to therapies based on other anti‐HIV‐1 agents. In this contest, 3,4‐dihydro‐2‐alkoxy‐6‐benzyl‐4‐oxypyrimidines (DABOs) have been the object of many studies aimed at identifying novel analogues endowed with potent inhibitory activity towards HIV‐1 wild type and especially drug‐resistant mutants. Accordingly, based on the encouraging results obtained from the biological screening of our internal collection of S‐DABO derivatives, we started with the systematic functionalization of the pyrimidine scaffold to identify the minimal required structural features for RT inhibition. Herein, we describe how the combination of synthetic, biological, and molecular modeling studies led to the identification of two novel subclasses of S‐DABO analogues: S‐DABO cytosine analogues (S‐DABOCs) and 4‐dimethyamino‐6‐vinylpyrimidines (DAVPs).
Modeling and Selection of Flexible Proteins for Structure‐Based Drug Design: Backbone and Side Chain Movements in p38 MAPK
Authors: Subramanian Jyothi , Sharma Somesh , B‐Rao Chandrika 
Published: December 2007

AbstractReceptor rearrangement upon ligand binding (induced fit) is a major stumbling block in docking and virtual screening. Even though numerous studies have stressed the importance of including protein flexibility in ligand docking, currently available methods provide only a partial solution to the problem. Most of these methods, being computer intensive, are often impractical to use in actual drug discovery settings. We had earlier shown that ligand‐induced receptor side‐chain conformational changes could be modeled statistically using data on known receptor–ligand complexes. In this paper, we show that a similar approach can be used to model more complex changes like backbone flips and loop movements. We have used p38 MAPK as a test case and have shown that a few simple structural features of ligands are sufficient to predict the induced variation in receptor conformations. Rigorous validation, both by internal resampling methods and on an external test set, corroborates this finding and demonstrates the robustness of the models. We have also compared our results with those from an earlier molecular dynamics simulation study on DFG loop conformations of p38 MAPK, and found that the results matched in the two cases. Our statistical approach enables one to predict the final ligand‐induced conformation of the active site of a protein, based on a few ligand properties, prior to docking the ligand. We can do this without having to trace the step‐by‐step process by which this state is arrived at (as in molecular dynamics simulations), thereby drastically reducing computational effort.