bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vanadium(IV) dimer complexes containing [V(o‐C6H4OS)3]2− fragment and caged sodium ions
Authors: Weng Lin‐Hong , Kang Bei‐Sheng , Chen Xue‐Tai , Hong Mao‐Chun , Lei Xin‐Jian , Hu Yong‐Han , Liu Han‐Qin 
Published: September 2010

AbstractTris[o‐mercaptophenolato]vanadium(IV) dimer complexes (A)2[V(mp)3NaLL']2 (A = Ph4P+, H2mp = o‐mercaptophenol, L = MeCN, L'=EtOH, (1); L' = MeOH, (2)) were prepared by the reaction of anhydrous VC13, and Na2mp in the molar ratio 1:3. Complex (3) (A = Et4N+, L=L' = MeOH) was prepared by the reaction of VC13, Na2mp and Li2S in the molar ratio 1:2:1. The complexes were characterized by X‐ray diffraction crystallography, infrared spectra, magnetic susceptibility, and cyclic voltammetric measurements. Complex 2 crystallizes in the triclinic space group P1 with a=12.813(6), b = 14.199(4), c = 12.790(5) Å, α = 112.72(2), β = 104.24(4). γ = 88.68(4)°, V = 2073.6 Å3, and Z=1. The structure was refined to R=0.058. Complex 3 crystallizes in the mono‐clinic space group P21/n with a=12.359(3), b=17.452(6), c=14.829(13) Å, βequals;96.51(5)°, V=3177.8 Å3, and Z=2. The final R factor is 0.067. Both of the anions of 2 and 3 contain two [V(mp)3]2− fragments linked by sodium ions through the μ3‐O bridges with a crystallographic center of symmetry. The V(IV) atom is in a coordination environment intermediate between a trigonal prism and an ideal octahedron.
Computer‐assisted optimization for the selection of mobile phase in semi‐preparative HPLC
Authors: Wang Qin‐Sun , Gao Ru‐Yu , Yan Bing‐Wen 
Published: September 2010

AbstractA computer‐assisted method is presented for optimization for the selection of mobile phase composition in semi‐preparative HPLC. The optimization for the expected separation is based on a polynomial estimation from five preliminary runs. Statistical scanning technique was used for optimization. Double criteria simulation system (DCSS) is established for chromatographic performance measurement in this method. The validity of the optimization strategy is confirmed by applying it to a technical Cypermethrin separation. Excellent agreement is obtained between the predicted and experimental results.
The correlation between molecular structure parameters of O‐ethyl N‐isopropyl phosphoro(thioureido) thioates and their retention data in RP‐HPLC
Authors: Wang Qin‐Sun , Gao Ru‐Yu , Yang Hua‐Zheng , Yan Bing‐Wen 
Published: September 2010

AbstractA retention prediction system (RPS) of seven O‐ethyl N‐isopropyl phosphoro(thioureido)‐thioates in reversed phase HPLC was investigated. The system is based on the solvent selectivity triangle concept. Three molecular structure parameters (hydrophobicity II, substituent length L, and substituent maximum with B5) were used to describe the quantitative structure‐retention relationships. With these quantitative relationships, the retention behaviours of other eight homologs for different mobile phase composition were predicted. The predicted values were consistent with the measured values within relative error of 10%, which means that it is possible to apply the reported method to predict retention values for qualitative purposes for different mobile phase compositions.
Stereospecific synthesis of (E)‐furfurylalkenes from alkenyldisiamylboranes and furfuryl chloride
Authors: Li Nan‐Sheng , Chen Yan , Deng Min‐Zhi 
Published: September 2010

AbstractThe Pd(PPh2)4‐catalyzed coupling reaction of alkenyl‐disiamylboranes with furfuryl chloride in the presence of f‐BuOK afforded (E)‐furfurylalkenes stereospecifically in good yields.
Influence of chemical dealumination on the properties of USY zeolite
Authors: Bao Shu‐Lin , Wu Peng , Xu Qin‐Hua 
Published: September 2010

AbstractThree series of dealuminated Y zeolites have been prepared by chemical extraction of hydrothermally dealuminated Y zeolite (USY) with H2Na2EDTA, HCl and H4EDTA. The unit cell constant, mesopore distribution, acidity and extraframework aluminum (EFAL) of the zeolites were studied with XRD, chemical analyses, adsorption, IR and NH3‐TPD techniques. It was shown that H2Na2EDTA only removed EFAL species deposited in the pores of USY, by contrast, HCl and H4EDTA extract both extraframework and framework aluminum, and make the zeolite framework further dealuminated. Adsorption tests gave evidence that a secondary pore system exists in these dealuminated zeolites. H2Na2EDTA extraction increased both micropore and mesopore volumes, but after HCl and H4EDTA treatments, new mesopores formed and the micropore volume was decreased. The pyridine‐IR and NH3‐TPD measurements demonstrated that EFAL had no evident contribution to the zeolite acidity.
Studies on macrocyclic diterpenoids. V. Synthesis of (±)‐sarcophytol‐A benzyl ether
Authors: Li Wei‐Dong , Li Ying , Mao Jian‐Min , Li Yu‐Lin 
Published: September 2010

AbstractThe title compound, sarcophytol‐A benzyl ether has been synthesized through 13 steps by employing acetone and geraniol as starting materials. The key steps in the synthesis were double bond migration reaction of allylic alcohols 5 and 6, phase transfer catalytic coupling (PTC) reaction of II with 7 and the cyclization reaction of dicarbonyl acyclic precursor induced by TiCl3‐AlCl3(3:1)/Zn‐Cu system.
Studies on polyhaloalkanes. I. Radical addition of polyfluoroalkyl iodides to diethyl allylphosphonate
Authors: Huang Bing‐Nan , Wang Ke‐Yang , Huang Wei‐Yuan , Prescher Dietrich 
Published: September 2010

AbstractRadical addition of polyfluoroalkyl iodides to the CC double bond of diethyl allylphosphonate was carried out in CH2Cl2‐H2O two‐phase medium in the presence of sodium dithionite to give diethyl 3‐polyfluoroalkyl‐2‐iodopropylphosphonates (3) in excellent yields. Compounds 3 were then converted to diethyl polyfluoroalkanephosphonates (4) by zinc‐reduction. Thus a facile method for preparing polyfluoroalkanephosphonates is realized.
Isomerization kineties of spirocompounds incorporated into sodium dialkylmethyl sulfate bilayer membranes
Authors: Wang Guan‐Wu , Lei Xue‐Gong , Li Zi‐Zhong , Liu You‐Cheng , Fan Mei‐Gong 
Published: September 2010

AbstractThe isomerization kinetics of a spiropyran (1) and a spirooxazine (2) embedded in bilayer membranes of sodium 1‐pentadecylhexadecyl sulfate (3) and sodium 1‐undecyl dodecyl sulfate (4), respectively, were investigated. The thermal decay of 2 obeyed first‐order kinetics, whereas that of 1 consisted of two simultaneous first‐order processes. Kinetic parameters; were obtained from Arrhenius plots.
A novel mixed‐coordination cobalt(III)complex:synthesis and structure of Co(III)(mpp)(Hmpp)(n‐Bu3P)2
Authors: Xu Yong‐Jin , Kang Bei‐Sheng , Chen Xue‐Tai , Hu Yong‐Han 
Published: September 2010

AbstractComplex Co(III)(mpp)(Hmpp) (n‐Bu3P)2 (1. H2mpp= 2‐mercapto‐3‐pyridinol) was obtained from the reaction of CoCl2 with H2mpp, n·Bu3P and Na metal in EtOH. The Co atom in a distorted octahedral geometry is coordinated with donor atoms N, O, P and S. The two H2mpp ligands form two different chelate rings with the Co(III) ion: one 5‐membered and the other one 4‐membered, while the two n‐Bu3P ligands are in the axial positions with the angle P(1)‐Co‐P(2) of 176.1:
Structural elucidation of sex pheromone components of the Geometridae Semiothisa cinerearia (Bremer et Grey) in China
Authors: Li Zheng‐Ming , Yao En‐Yun , Liu Tian‐Lin , Liu Zi‐Ping , Wang Su‐Hua , Zhu Hai‐Qing , Zhao Gang , Ren Zi‐Li 
Published: September 2010

AbstractAn extract from the female sex gland of Semiothisa cinerearia attracted conspecific males in field tests. A major active component was isolated from the extract and identified by GC‐MS, GC‐IR and microchemical reactions as cis‐3,4‐epoxy‐(Z,Z)‐6. 9‐heptadecadiene, which showed strong EAG response. Another minor yet important component was identified as (Z,Z,Z)‐3,6,9‐heptadecatriene.
A novel regio‐ and stereo‐specific hydrohalogenation reaction of 2‐alkynoic acids and their derivatives
Authors: Lu Xi‐Yan , Zhu Guo‐Xin , Ma Sheng‐Ming 
Published: September 2010

AbstractThe nucleophilic hydrohalogenation of 2‐alkynoic acids and their derivatives by heating with lithium halides in HOAc afforded the thermodynamically unfavorable 3‐halo‐2 (Z)‐alkenoic acids and their derivatives stereospecifically
The three‐dimensional structure of trichosanthin refined at 2.7 Å resolution
Authors: Xia Zong‐Xiang , Zhang Lei , Zhang Zhi‐Ming , Wu Shen , Dong Yi‐Cheng 
Published: September 2010

AbstractThe three‐dimensional structure of trichosanthin crystallizing in space group C2 has been refined at 2.7 Å resolution from a previously reported starting model at 3 Å resolution based on a solvent flattened map and the revised primary structure consisting of 247 amino‐acids. The final R‐factor is 19.2% with the root mean‐square deviations of 0.018 Å from ideal bond lengths and of 2.2˙ from ideal bond angles. Trichosanthin molecule is composed of two domains, the large domain consisting of 181 amino‐acid residues starting from N‐terminus and the small domain consisting of the rest of the amino‐acid residues. The molecule contains eight α‐helices. five β‐sheets made of sixteen β‐strands, and some reverse turns. It is noteworthy that some of the α‐helices and β‐sheets show irregular hydrogen bonding patterns. Six of the thirteen residues absolutely conserved in eleven ribosome‐inactivating proteins are located in a cleft near the interface of the two domains and they are likely to be active sites. Three additional conservative residues located in the cleft region might make some functional contribution as well.
A theoretical analysis and its application of the second order EC reactions at microelectrodes under steady‐state conditions
Authors: Zhuang Qian‐Kun , Chen Hong‐Yuan 
Published: September 2010

AbstractWith a new approach, the general current expressions of two typical second order catalytic reactions are obtained for disk, hemispherical and spherical microelectrodes under steady‐state conditions. This approach is based on the concept of reaction layer. For the second order EC reactions, we also discussed how it is possible to observe pseudo‐first order or second order behavior. This consideration allows the study of the fast chemical reactions and systems where the bulk concentrations of the reactants are nearly equal. Regeneration of Fe3+(EDTA) with H202 was selected as an example of a rapid catalytic reaction.
The isotopic effects in the IR‐multiphoton excitation of molecules with c2v symmetry
Authors: Ding Shi‐Liang , Liu Wen‐Jian , Deng Cong‐Hao 
Published: September 2010

AbstractQuantum dynamical calculations for the IR‐multiphoton excitation of H2O, D2O and T2O are presented using a generalized Hamiltonian for XY2 molecules. The energy spectra obtained from this Hamiltonian are in good agreement with those of the experiments. The long time average of the transition probabilities and the isotopic effects are discussed in detail,
An unexpected Diels‐Alder type cycloaddition of cyclic enone ethylene ketals
Authors: Chow Yuan L. , Cheng Xian‐En , Zhang Yu‐Huang 
Published: September 2010

AbstractThe ethylene ketal of 2‐cyclopentenone and 2‐cyclohexenone in acetonitrile in the presence of a trace of an acid rapidly undergoes the Diels‐Alder type dimerization. The products are regiospecific but not stereoselective and are hydrolysed sequentially to afford keto‐ketals and diketones whose structures are determined by extensive applications of NMB spectroscopy.
Crystal and molecular structure of 2,3‐benzo‐1,4,7,13‐tetraoxa‐10‐selenacyclopentadeca‐2‐ene
Authors: Xu Han‐Sheng , Li Wei‐Ping , Liu Xiu‐Fang , Huang You‐Qing , Hu Sheng‐Zhi 
Published: September 2010

AbstractThe crystal structure of 2,3‐benzo‐1,4,7,13‐tetraoxa‐10‐selenacyclopentadeca‐2‐ene was determined. C14H20O4Se, Mr=331.27, orthorhombic, Pbca, a=18.445(3) Å, b=16.334(4) Å, c=9.232(2) Å, V=2781.3 Å3, Z=8, Dx=1.582 Mg m−3, λ(Mo Kα)equals;0.71073 Å, μequals;26.77 cm−1, F(000)equals;1360, T=297 K, R=0.0329, Rw =0.0438 for 2192 reflections with I > 3 s̀(I). The crystal structure is closely related to that of benzo‐15‐crown‐5 (at 123 K), whereas the molecular geometry of the two coronands is different according to their torsion angles calculated and the shapes exhibited.
Reactions of magnesium formate on supports
Authors: Han Qiao‐Feng , Yang Xu‐Jie , Deng Li‐Jun , Wang Xin , Lu Lu‐De , Hua Wan‐Sheng 
Published: September 2010

AbstractThermal decomposition of supported magnesium formate has been studied by gas chromatography. The reaction paths of decomposition of supported magnesium formate depend on the nature of the supports. For Mg(HCO2)2/HZSM‐5, the zeolite behaves as a dehydration catalyst to give CO and H2O at lower temperatures; when the zeolite is modified by phosphorus, the methanation reaction will be partly restrained. In the case of Mg(HCO2)2/AC, strong adsorption of CO2 leads to the formation of the shoulder peak of CO2 at higher temperatures, however, CH4 disappears after modified by phosphorus. For Mg(HCO2)2/Al2O3, the dehydrogenation of HCO2− takes place on the surface of Al2O3. The decomposition of Mg(HCO2)2 on SiO2 in hydrogen yields two peaks of CO and only one appears after modified by phosphorus. When Mg(HCO2)2 decomposes on MgO, the first peak of CO2 arises from the reaction of surface Mg2+ with HCO2− from dissociated Mg(HCO2)2.
Studies on solid state reactions of coordination compounds. LXIII. Solid state synthesis of a series of tetranuclear Mo(W)—Ag mixed‐metal clusters. Crystal structures of [(n‐Bu)4N]3[MoOS3Ag3Br4] and [(n‐Bu)4N]3[WS4Ag3Cl4]
Authors: Lang Jian‐Ping , Xin Xin‐Quan , Cai Jin‐Hua , Kang Bei‐Sheng 
Published: September 2010

AbstractA series of tetranuclear Mo(W)‐Ag mixed‐metal clusters have been synthesized by making use of the solid state reactions of [NH4]2[MYS3](M= Mo, W; Y= O, S), AgX(X= Cl, Br, I) and (n‐Bu)4NX' (X' =Cl, Br), two of which [(n‐Bu)4N]3[MoOS3Ag3Br4] (1) and [(n‐Bu)4N]3[WS4Ag3Cl4] (2) have been structurally characterized by X‐ray analysis. The crystal data: 1, cubic, P43m, αequals;12.093(4) Å, Z=1, R =0.076; 2, cubic, P43m, αequals;12.059(2) Å, Z =1, R =0.075. The cluster anion core [Ag3MS3X'] of the two compounds can be viewed as a cube in which the four metal atoms and the four non‐metal atoms are statistically distributed, respectively. Substitution reaction with PPh3 ligand is also discussed for this type of tetranuclear clusters.
Single‐Li+ conductivity in ionomeric network
Authors: Zhang Sheng‐Shui , Liu Qing‐Guo , Yang Lei‐Ling , Farrington Gregory C. 
Published: September 2010

AbstractIonomeric networks (IN) with lithium sulfate and salt‐solvating oligo(oxyethylene) chain were synthesized on the purpose of improving the conductivity of single‐Li+−ionic conductors. Li+−ionic conductivity depends considerably on the salt content of the INs although the apparent degree of cross‐linking is fixed in a constant of 10 mol%. As salt content (Li/O value) equals 0.0467, conductivity of the IN containing neither small‐molecular salt nor low molecular weight plasticizer reaches a maximum of 7×10−6 S/cm at 25°C. Temperature‐conductivity relationship of the INs shows curved Arrhenius plots, suggesting that the ionic conduction is primarily influenced by segmental motion of the polymer host. In addition, WLF (Williams‐Landel‐Ferry) equation is used to analyze the conductivity data, from which the related WLF parameters are determined.
Kinetic and mechanism of oxidation of thiocarbohydrazide and its metal complex by acid bromate in aqueous and partial aqueous media
Authors: Pardhasaradhi V. , Hegde A. Chitharanjan , Gowda B. Thimme 
Published: September 2010

AbstractThe kinetics of oxidation of thiocarbohydrazide in the free and zinc(II)‐bound states by acid bromate have been studied in aqueous and water‐acetic acid (1:1, V/V) media under varying conditions, both in the absence and presence of added bromide ion. The rates of oxidations show first order kinetics in [bromate] in all the cases, but exhibit different kinetic behaviour in [substrate] and [H+]. Oxidation of TCH in aqueous medium shows zero order in [TCH] and nearly second order in [H+], while oxidation in aqueous acetic acid shows two ranges in [H+]. The rate shows first and fractional order kinetics in [TCH] in the first and second acid ranges. Kinetics observed in the presence of Br− are similar to those observed for oxidation of TCH in second acid range. In addition, the reaction shows fractional order in [Br−]. Oxidation of TCH in Zn(II)‐bound state exhibits first order kinetics in [substrate] and second order in [H+]. Increase in ionic strength of the medium decreases the rate in all the cases. Increase in acetic acid composition of the solvent increases the rate. Mechanisms consistent with the observed results have been considered and the rate laws deduced. The rate limiting steps have been identified and the coefficients of these steps have been calculated at different temperatures. The related activation parameters have also been computed. The validity of the deduced rate laws has also been tested by recalculating the rate constants from them as [TCH] and [H+] are varied.
Benzoylation of benzene and substituted benzenes catalyzed by superacid ZrO2:H2SO4
Authors: Jia Cheng‐Guo , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: September 2010

AbstractSuperacid ZrO2:H2SO4 showed high activity in Friedel—Crafts benzoylation of benzene and substituted benzenes such as chlorobenzene, toluene and 1,3,5‐trimethylbenzene. Benzophenones in 90–100% yields were obtained with catalytic amount of superacid ZrO2:H2SO4. The calcination temperature greatly influenced the acid strength and activity of the superacid ZrO2:H2SO4. The superacid has both Lewis and Bronsted acid sites. The reversibility of Friedel—Crafts benzoylation and transacylation were observed over the superacid. The used superacid could be readily regenerated and showed identical benzoylation activity to toluene.
Studies on the biosynthesis of arteannuin. IV. The biosynthesis of arteanniuin and arteannuin B by the leaf homogenate of Artemisia annua L.
Authors: Wang Yu , Xia Zhi‐Qiang , Zhou Feng‐Yi , Wu Yu‐Lin , Huang Jing‐Jian , Wang Zhi‐Zhong 
Published: September 2010

AbstractArteannuic acid and (‐)11R,13‐dihydroarteannuic acid are the key intermediates in the biosynthesis of arteannuin by the leaf homogenate of Artemisia annua L., and arteannuic acid and epoxyarteannuic acid are the intermediates of arteannuin B. and epoxyarteannuic acid can not be transformed into arteannuin by the homogenate.
Localized molecular orbital studies of certain compounds with [A3X3] six‐membered rings
Authors: Li Jun , Liu Chun‐Wan , Lu Jia‐Xi 
Published: September 2010

AbstractThe localized molecular orbitals (LMOs) of certain quasi‐aromatic organic and inorganic molecules with six‐membered rings have been calculated by virtue of the ab initio method using STO‐3G and 4–31G basis sets as well as the CNDO/2 method. It is shown that there exists extensively‐delocalized p‐pπ bonding in these quasi‐aromatic systems. The localized pictures of the π‐type LMOs for the heterocyclic and homocyclic systems from the σ‐π localization scheme are discussed. The Generator Orbital approach is utilized to account for the bonding patterns.
Structure effect of nucleotides in terbium(III)—nucleotide fluorescent reaction New evidence for the binding sites of terbium(III) on nucleotides
Authors: Li Yuan‐Zong , Chang Wen‐Bao , Ci Yun‐Xiang 
Published: September 2010

AbstractUpon addition of Tb3+ to 16 nucleotides and homopolynucleotides, all of them showed a characteristic green emission from Tb3+, but with much different intensity, upon excitation in the aromatic region of bases. The result suggested that nucleotides with at least one carbonyl group in nucleotide bases are better enhancers to the fluorescence of Tb3+. The complexes of ATP, GDP and GTP with Tb3+ are synthesized as two types of models. Guanine type nucleotides with one carbonyl group in the bases are the best enhancers, while adenine type nucleotides with no carbonyl group in the bases are poorest enhancers to the fluorescence of Tb3+. Comparing the IR spectra of ATP, GTP, GDP and their Tb3+ complexes suggested that C‐6 carbonyl group in GTP and GDP may be involved in complex formation, which may be responsible for the effective energy transfer. This is further supported by comparing the UV spectra of ATP, Poly(A), GTP, and Poly(G) with their Tb3+ complexes in water solution.
Complexation of hypocrellins and bivalent metals and one‐electron reduction of the complexes with electron donor
Authors: An Jing‐Yi , Tian Fei , Hu Yi‐Zhen , Jiang Li‐Jin 
Published: September 2010

AbstractThe complexation of HA (or HB) with bivalent metals was examined by UV‐Vis and NMR spectroscopy, and all of the complexes obtained have a metal‐ligand ratio of 1:1. The photoinduced reduction of the complexes of HA‐Zn2+ and HA‐Mg2+ (or HB‐Zn2+, HB‐Mg2+) in the presence of 1‐benzyl‐1,4‐dihydro‐nicotinamide as the electron donor was investigated by UV‐Vis and ESR spectroscopy. The studies demonstrated that illumination of the complexes of HA(HB)‐Zn2+ and HA(HB)‐Mg2+ led to the accumulation of the chelated semiquinone radical anions.
Amino acid identification and sequence analysis of peptides by reaction mass spectrometry
Authors: Yang Hou‐Jun , Hu Xiao‐Yu , Chen Yao‐Zu 
Published: September 2010

AbstractFast atom bombardment mass spectrometry (FAB‐MS) is applied to distinguish N‐terminal series ions from C‐terminal series ions of a peptide by on‐probe acetylation, it provides valuable information about the sequence of an unknown peptide. The FAB mass spectra contain a number of characteristic ions at low‐mass region in addition to the sequence ions at high‐mass region. It was found that the ions below m/z 200 are characteristic of the amino acid composition of the peptide, from which the amino acid composition of the peptide could be estimated. Additionally, mixture analysis is also discussed.
Enrichment of trace cerium subgroup rare earths by means of ion flotation
Authors: Liang Shu‐Quan , Ma Hui‐Min 
Published: September 2010

AbstractThe possibility of ion flotation of cerium subgroup rare earths (Ce‐subgroup), was explored. Various factors affecting the. flotation efficiency were investigated. The results showed that, by using sodium tetradecyl sulfate as the collector of trace Ce‐subgroup and frother, over 95% of Ce‐subgroup at ng/g levels could be separated from pH 2.3 media in 10—15 min. The proposed method has been applied to the determination of Ce‐subgroup in a polluted farmland soil reference material (GBW 08303) with satisfactory results.
A strategy for synthesis of polymer‐protective bimetallic colloids
Authors: Wang Yuan , Gui Lin‐Lin , Tang You‐Qi 
Published: September 2010

AbstractA strategy for the synthesis of polymer‐protective bimetallic sols is proposed which has the advantage of the strong protective effect of the polymer agent on one of the composites to stabilize the bimetallic colloidal particles. This strategy is certified to be useful to the predication of the formation of stable bimetallic colloids protected by polymer and to the control of the particle size to a certain extent. A series of new PVP‐protective bimetallic colloidal dispersions containing noble metal element (Pt, Rh, Pd), light transition metal element (Co, Fe), and boron are obtained from the corresponding salts by the methods of reduction by stage and coreduction, using the NaBH4 as reductant. The TEM, XRD and EPMA measurements indicate the formation of bimetallic colloids. An interesting kind of coil aggregation is observed in the systems of PVP‐Pt‐Co and PVP‐Rh‐Co prepared by the method of reduction by stage.