bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the synthesis of some new biflavanoids VII. Synthesis and structures of 2,2″‐biflavanones
Authors: Li Yu‐Lin , Zhang Fang‐Jie , Wang Qi‐Guang 
Published: September 2010

AbstractA new approach to the synthesis of 2,2″‐biflavanones by the reductive dimerization of flavones is reported. The products, the racemate and meso biflavanones, have been separated and their structures have been determined on the basis of their spectral data. The configuration of 3b has been determined by X‐ray crystallography as well.
Investigation on the potential barrier to internal rotation in molecules—Ab initio calculation and energy partition of the internal rotation barrier in complex molecule H3N–BH3
Authors: Zhang Qi‐Yuan , Yan Ji‐Min 
Published: September 2010

AbstractBased on the ab initio/6–31G* calculation, the potential barrier to internal rotation in molecule H3N‐BH3 has been studied by means of PD/LSF atomic charge model and Buckingham(exp‐6–1) energy partition method. The results indicate that the order of the contributions of the components to the total energy barrier ΔE is |ΔVed|(electrostatic)>|ΔV| (charge transfer)> |ΔVex| (exchange repulsion) > |ΔVdi| (dispersion). For ΔVes there are maxima at θ = 30° and 90°, and a saddle at θ = 60°. There are good linear relationships for the total barrier ΔE, ΔVex and ΔV| with cos3θ respectively, and the same for the dipole moment from PD/LSF model (μPD) and that from ab initio calculation (μQM) vs. cos3θ respectively.
Characterization and phase transition study for vesicles of fluorocarbon amphiphiles with 1,3‐disubstituted glycerol structure
Authors: Liang Kang‐Ning , Hui Yong‐Zheng 
Published: September 2010

AbstractThis paper presents the preparations and characterization of vesicles of four new fluorocarbon amphiphiles with 1,3‐disubstituted glycerol structure in common and different headgroups (OH, 1; CO2H, 2; quaternary ammonium salt, 3; and pyridinium salt, 4). These vesicles have higher transition temperature due to the stronger hydrophobic interaction between fluorocarbon chains. Addition of fluorocarbon additives with carboxylic acid or quaternary ammonium salt head group respectively shows different influences on phase behavior of vesicles of 2. These results are discussed based on the interaction within headgroup, hydrophobicity and specific mutahydrophobic interaction between fluoro‐ and hydrocarbon chains.
Synthesis and reactions of some 6‐aryl and 2,6‐diaryl‐4‐(4′‐antipyrinyl)‐2,3,4,5‐tetrahydropyridazin‐3‐ones and screening for their antibacterial activities
Authors: Sayed G. H. , Shiba S. A. , Radwan A. , Mohamed S. M. , Khalil M. 
Published: September 2010

AbstractSome new pyridazinone derivatives(3) were synthesized through addition of antipyrin to β‐aroylacrylic acids (1) followed by cyclization of the adducts. Reactions of 3 with ethyl bromoacetate, benzenesulfonyl chloride, benzoyl chloride and POCl3 give N‐substituted products and monochlorosubstituted pyridazines (4), respectively. The reactions of the latter with thiourea give unexpected dithio‐derivatives (5), which react with phenylhydrazine to give pyrazolopyridazino pyridazine derivatives (6). Reactions of 2 with NH2OH in ethanol and pyridine afford oxime and oxazinone derivatives 7 and 8, respectively. The antibacterial activities of several compounds were screened.
Studies on electrical properties of system La2‐x(Sr1‐yCay)xNiO4
Authors: Meng Jian , Ren Yu‐Fang , Pa Ya‐Nan 
Published: September 2010

AbstractA new series of solid solutions of composition La2 1.4) were prepared. All the members of the system are of the tetragonal K2NiF4 type structure. The tetragonality ratio c/a shows a progressive decrease with increasing y except for the group of x = 1.4. The room temperature resistivity exhibits a gradual increase with y, which is interpreted by assuming that the single eg electron of Ni3+ is present in localized dZ2 orbital but the te electron gradually becomes itinerant because it is delocalized into dx2y2 orbital leads to a strong Ni3−O2− covalent interaction with increasing the Sr content. Variation of resistance with temperature shows semiconducting properties except for the composition of x=1.4, y<0.3 which shows a semiconductor‐to‐metal transition.
Multinuclear NMR study of lanthanide(III) complexes of 1,2‐PDTA in aqueous solution
Authors: Song Rui‐Fang , Zhang Cun‐Zhi , Li Fei , Hua Shi‐Ying 
Published: September 2010

AbstractThe complexation of lanthanide(III) cations with 1,2‐propanediaminetetraacetate (1,2‐PDTA) in aqueous solution has been investigated by 10Na, 35Cl, 2H and 11O NMR shift measurements. It has been shown that the contact shifts are dominant for 17O, 16Cl and 2H (only for the heavier lanthanide series) and the pseudocontact shifts are dominant for 25Na. It is suggested that the 1,2‐PDTA ligand is bound pentadentately via the two nitrogens and the three carboxylates for the lighter lanthanide complexes, hexdentately via the two nitrogens and the four carboxylates for the heavier ones. The numbers of the water coordinated were determined. The small amount of chloride anion in inner coordination sphere was observed.
Determination of thorium with DBF‐arsenaz by flow‐injection analysis
Authors: Yang Yi , Cai Ru‐Xiu , Zeng Yun‐E 
Published: September 2010

AbstractA sensitive, selective, rapid, simple, and convenient method for the determination of thorium was developed. The method was based on the color reaction of thorium with DBF‐arsenazo in a strong acidic medium (4 mol/L HCl). The flow‐injection technique was used with an automated flow‐injection analyzer. Beer's law was obeyed in the range of 0–1.4 μg/mL. The relative standard deviations were less than 1%.
Phosphonium and arsonium ylides. XVII. A facile synthesis of methyl 2,6‐bisperfluoroalkylbenzoates via acyclic precursors
Authors: Ding Wei‐Yu , Cao Wei‐Guo , Xu Zhen‐Rong , Shi Zhi‐Jian , Yao Yuan 
Published: September 2010

AbstractThe title compounds 6a—6f were prepared with high yield via intramolecular Wittig reaction of methyl 3‐perfluoroalkyl‐6‐peifluoroacyl‐2‐triphenylphosphoranylidenchex‐3,5‐dienoates (5a—5i) which were obtained from the reaction of 3‐perfluoroacylprop‐2‐enylidenetriphenylphosphoranes (3a—3c) with methyl perfluoroalkynoates (4a—4c).
Quenching of zinc phthalocyanine excited states by viologen surfactant assemblies—The influence of microenvironment
Authors: Liu Ji‐Xiang , Zhou Qing‐Fu , Xu Hui‐Jun 
Published: September 2010

AbstractA series of functional surfactants of N‐alkyl‐N′‐butyl viologens has been synthesized. The quenching of excited singlet and triplet states of zinc phthalocyanine was studied in DMSO and in mixed micelles containing the functional surfactant as one and cationic cetyl trimethylammonium bromide (CTAB), anionic sodium dodecylsulfate (SDS) and neutral TX‐100 surfactant as the other component. Fluorescence quenching and laser photolysis studies indicate that the functional surfactants are solubilized at different sites in micelles, the process depends on chain length and exerts great influence on the quenching of zinc phthalocyanine excited states.
Structural comparison to the molybdenum site of nitrogenase. Synthesis and crystal structure of binuclear oxomolybdenum(V) complex with both o‐mercaptophenolate and alkoxide ligands
Authors: Hu Yong‐Han , Kang Bei‐Sheng , Chen Xue‐Tai , Huang Liang‐Ren , Weng Ling‐Hong , Xu Yong‐Jin 
Published: September 2010

AbstractComplex (n‐Bu4N)[Mo2O2(OMe)(mp)3] [1, mp = (o‐OC6H4S)2−] was synthesized by the reaction of MoOCl3(THF)2 and Na2mp in EtOH and crystallized in monoclinic space group P21/n with crystal data: a = 13.910(3), b = 23.554(3), c=12.558(2) Å, β = 105.20(2)˙. Z = 4, Do = 1.455g/ cm3, final R = 0.077 for 5325 reflections [I>3s̀(I)]. The two [Mo(O)mp]+ moieties are bridged by one 1,2‐bidentate ligand mp2− with exceedingly small bite angle (69.0˙) and bite distance · (2.70Å) and by a methoxy group. The structure can be interpreted as two distorted octahedra around the Mo atoms sharing a face. Attempts have been made to provide structural informations for the syntheses of modelling compounds of FeMoco by comparing the Mo—O and Mo—S bond distances of o‐mercaptophenolate ligated compounds to those of the molybdenum site of nitrogenase.
Studies on polyhaloalkanes. II. A facile method for mono‐fluorination of α, ω‐dihaloperfluoroalkanes
Authors: Huang Bing‐Nan , Prescher Dietrich 
Published: September 2010

AbstractA facile monofluorination of α, ω‐dihaloperfluoroalkanes was achieved by the reaction of them with antimony trifluoride and chlorine in anhydrous antimony pentachloride when monofluorinated products were removed immediately after their formation from the reaction mixture by fractionation. The reaction conditions were also investigated.
Molecular structure of imidazolate bridged binuclear zinc complex and its single crystal ESR spectra doped with bridged Cu—Zn complex
Authors: Mao Zong‐Wan , Chen Dong , Han Shi‐Ying , Sui Yun‐Xia , Tang Wen‐Xia , Yu Kai‐Bei 
Published: September 2010

AbstractThe X‐ray crystal structure of [(dtma)ZnImZn(dtma)]C1O4·2.5H2O (Hdtma=4‐Diethyl‐enetriamineacetic acid) was determined. The crystal is of orthorhombic, space group Pbcn with a=14.104(5), b=14.897(5), c=25.384(9)Å, and Z=8. The least‐square refinement of the structure leads to conventional R factor of 0.066. The magnetic properties of [(dtma)CuImZn(dtma)]CIO4·2.5H2O were investigated. From the single crystal ESR spectra of Zn—Im—Zn dimer doped with Cu—Im—Zn complex, the anisotropic g and A tensors and electronic spin‐density of the Cu—Zn complex are obtained and the bonding nature of Cu is discussed.
Synthesis, structure and electrochemistry of dithiocarbamato phenthiolate oxo‐molybdenum(IV) complexes [MoO(SΦ)2(S2CNEt2)]‐
Authors: Zhuang Bo‐Tao , Pan Bing‐Hua , Huang Liang‐Ren , Lan An‐Jian 
Published: September 2010

AbstractThe reaction of Mo(0) complex [Mo(CO)4(S2CNEt2)]‐ with phenthiolate [Et4N]SΦ in acetonitrile in the presence of small amount of air affords a new oxo‐molybdenum complex [MoO(SΦ)2(S2CNEt2)], which crystallizes in two forms of crystals. [Et4N][MoO(SΦ)2Φ(S2CNEt2)] (1a) and [Et4N][MoO(SΦ)2(S2CNEt2)]Φ(CH3)2CHOH (1b). The structures of 1a and 1b were determined from three‐dimensional X‐ray data. 1a crystallizes in the monoclinic, space group Ce with a=12.321(4), b=15.245(4), c=16.087(9)Å; β= 98.44(4)Φ, V=2989Å3, Z=4, Dc = 1.35g/cm3 and R=0.031 for 2434 reflections [I>36(I)]. 1b crystallizes in the monoclinic space group F21/n with a=9.861(1), b=20.357(3), c=17.122(5)Å; β= 92.27 (2)*, V=3434.3Å3, Z=4; De = 1.29g/cm3 and R= 0.051 for 2852 independent reflections [I>3σ(I)]. The structures of 1a and 1b reveal that the anion [MoO(SΦ)2(S2CNEt2)]‐ contains a single oxo ligand coordinating to a molybdenum(IV) and the geometry around Mo(IV) atom is a distorted square pyramid. Interestingly, the solvate molecule isopropanol of 1b is linked to oxo group by a hydrogen‐bond of 1.928Å, leading to the increase of MoO bond distance (1.718Å). Mo—S distances are 2.44 and 2.39Å. The electrochemical behavior of 1 was discussed also.
Zinc transfer kinetics between Cd5Zn2‐metallothionein and apo‐carbonic anhydrase
Authors: Huang Zhong‐Xian , Hu Hong‐Yu , Gu Wei‐Qiang , Sun Jian‐Qun 
Published: September 2010

AbstractThe kinetics of zinc transfer reaction between rat liver CdsZn2‐MT and apo‐carbonic anhydrase has been studied. Low molecular weight ligands (LMWL) present different effect on the zinc transfer reaction. A possible association mechanism has been proposed where the formation of protein‐protein complex may be the rate‐determining stop.
Synthesis of 15‐hydroxy‐15(14→8)abeo‐5α, (8S)‐cholestane‐3,14‐dione
Authors: Li Tong‐Shuang , Li Yu‐Lin , Liang Xiao‐Tian 
Published: September 2010

AbstractThe synthesis of 15α‐hydroxy‐15(14→8)abeo‐5α,(8S)‐cholestanc‐3.14‐dione (1) from cholesterol in ten steps was described. The key step is the intramolecular aldol condensation of 3.14‐dioxo‐14.15‐seco‐5α‐cholestan‐15‐al (3).
Studies on hypersensitive transitions of Nd(III) in Nd(III)‐0‐diketone‐neutral ligand ternary compounds
Authors: Gao Jin‐Zhang , Yang Wei‐Dong , Yang Wu , Kang Jing‐Wan , Bai Guang‐Bi , Yu Geng‐Sun 
Published: September 2010

AbstractIn this paper, hypersensitive transitions of Nd( I) in Nd( I )‐β‐diketone‐neutra] ligand ternary coordination compounds (where p‐diketone = acetylacetone (AA), benzoylacetone (BA), dibenzoylmethane (DBM), 2‐thenoyl trifluoroacetone (TTA); neutral ligand = pyridine (Py). cr.a′‐dipyridyl (Dipy), phenanthroline (Phen) are studied and their intensities are given through dynamic coupling model. The results are in agreement with those observed and calculated using Judd‐Ofelt equation. It may be seen that the dynamic coupling mechanism provides major contribution to the intensity of hypersensitive transition. On the other hand, in order to get the intensity of 4I9/1→4G5/2 transition, the absorption spectra in 560–610 nm have been decomposed into three peaks by nonlinear fitting with Lorentzian and Gaussian function and the “pure” intensities of hypersensitive transitions have been obtained, which are agreeable to those computed by Judd‐Ofelt method and dynamic coupling model.
Study of association of alcohols in aprotic solvents by multinuclear NMR
Authors: Yan Xian‐Zh'Ong , Xue Yi , Du You‐Ru 
Published: September 2010

AbstractBinary mixtures of alcohols (ethyl, n‐butyl and n‐amyl) with several aprotic solvents, such as acetone, dioxane, THF, DMSO and DMP have been studied systematically by 1H, 13C, 15N and 17O NMR measurements. The concentration dependence of chemical shift of the solvent was used to evaluate equilibrium constants of the complexation of alcohols with the solvents. A relationship between the proton shift of alcohol uncombined with the solvent and its concentration was found, and the fraction of unassociated hydroxyl groups was thus quantitatively described. The effect of solvent on self association and complexation of the alcohol is discussed on the basis of the electron donicity of the solvents.
Distribution mechanism of protonated l,10‐phenanthroline between unbuffered aqueous and 1,2‐dichloroethane phases
Authors: Lin Sin‐Ru , Wang Fang , Lu Xin‐Gen 
Published: September 2010

AbstractThe faradaic ion transfer of protonated l.iO‐phenanthroline [H(Phen)+] across the interface between unbuffered aqueous and 1,2‐dichloroethane (DCE) solutions was investigated by means of current scan polarography at ascending aqueous electrolyte electrode, as well as chronopotentiometry. It follows from the splitting of the waves observed at the pH of aqueous phase (sodium sulfate solution) between 2.5–3.8 that neutral reagent (Phen) distributes into the aqueous phase, where it is protonated. The positive wave is associated with the mass transfer controlled by the H+influx, whereas the negative one is by the Phen influx. The reverse chronopotentiometry indicated that all the protonated transfer processes were reversible. A good agreement between experimental results and theoretical treatment was achieved. The aqueous acid dissociation constant of protonated Phen, K2 can be evaluated from the dependence of the wave heights on the pH in the base of the equilibrium.
Effect of secondary MO interaction on the regiospecificity in the reactions of tf‐ionones with singlet oxygen
Authors: Wu Guo‐Sheng , Tao Tao , Hu Jun , Zha Zhen‐Chuan , Wu Bi‐Qi 
Published: September 2010

AbstractThe ene reactions of a‐ionones with singlet oxygen were examined to ascertain the effect of secondary MO interaction between the reactants on the reaction regiospecificity. Exclusive formation of 3‐hydroxy‐V‐ionones found in the reactions reveals favorable interaction of singlet oxygen with the acyclic fl‐hydrogen atom. On the other hand, no formation of 3‐hydroxy‐0‐ionones implies that the steric requirement was not met for the bond formation between zwitterionic perepoxide with Ci‐hydrogen in the process. The MMP21 and MNDO calculations indicate minus value of the secondary interaction energy for the acyclic a‐hydrogen abstraction and a repulsion between the oxygen with C1‐hydrogen atom. Twisting tilting of the double bond may account for favorable attack of singlet oxygen on C3. An explanation of the excellent regiospecificity was addressed and placed in proper mechanic prospective.
Studies on the syntheses and properties of Schiff base type crown ethers
Authors: Wu Yang‐Jie , Zhao Bin , Zhao Li‐Wang , Shen Lian‐Fang , WU Dong‐Hui 
Published: September 2010

AbstractSight bis‐, two tris‐ and two mono‐crown ethers of Schiff base type have been prepared by the reaction of 4′‐formylbenzo‐15‐crown‐5 with diamines. Conductivity measurements show that the bis‐crown ethers form 1:1 complexes (crown ether unit : metal ion) with sodium ion and 2:1 complexes with potassium, rubidium and ammonium ion, respectively.
Studies on steroidal plant growth regulator 27. Stereoselective construction of the side chain of brassinosteroid by employing a separated dialkylation and a tandem dialkylation of the pyranone moiety
Authors: Zhou Wei‐Shan , Sun Li‐Qiang , Pan Xin‐Fu 
Published: September 2010

AbstractA stereocontrolled construction of the Bide chain of brassinosteroid was developed via the separated dialkylation and the tandem dialkylation of the pyranone moiety as the key step.
Time development of surface enhanced Raman intensities of the adsorbed pyrazine molecules on the silver electrode as the applied voltage varies
Authors: Wu Guo‐Zhen , Huang Yi 
Published: September 2010

AbstractIn this work, the time development of surface enhanced Raman intensities of the vibrational modes involving the ring skeleton and the C—H motions of the pyrazine molecule as the applied voltage on the silver electrode is shifted between −0.2 V and −0.5 V (vs. saturated calomel electrode) is reported. The observation shows that there are two processes of enhancement involved during this shift of applied voltage. One is vibrational mode dependent while the other is not. The detailed behavior of these two processes of enhancement is discussed along with the retarded response of the Helmholtz double layer structure to the change of the applied voltage on the electrode.
Electronic structure and photoelectron spectrum assignment of allene
Authors: Wang Zhi‐Zhong , Yang Ming , Yang Zhong‐Zhi 
Published: September 2010

AbstractIn this paper a series of ab initio SCF and configuration calculations were reported for the ground state and excited states X2E, A2E, 2B2 and 2A1 of allene. For ground state X2E Jahn‐Teller distorsion was discussed and a twisted angle of 50° and a torsional barriers of 0.21–0.51 eV were derived. Based on calculated results, the experimental photoelectron spectrum of allene has been assigned.
XPS study of Ba0.6K0.4BiO3
Authors: Zhao Liang‐Zhong , Norton Michael L. 
Published: September 2010

AbstractSingle crystal Ba0.6K0.4BiO3 was studied by using XPS. The results show that there is no evidence for the presence of Bi5+ in single crystal of Ba0.6K0.4BiO3; instead, there is evidence for the presence of mixed valent Bi3+ and Bi(3+)‐δ. Moreover, the Ols XPS results suggest the presence of mixed valent O2− and O1−, and the valence band spectrum suggests the high degree of covalency for Bi—O bonds.
Studies on cyclopent‐2‐enone. II. The diastereoselectivity in Lewis acid mediated reactions of enol silyl ether of cyclopent‐2‐enone with aldehydes
Authors: Zhang Xiao‐An , Campbell M. M. , Brown D. W. 
Published: September 2010

AbstractThe aldol reaction of the silyl enol ether of cyclopent‐2‐enone with aldehydes is mediated by various Lewis acids. Threo isomers are the major diastereoisomers formed in most cases. A reverse diastereoselectivity was observed when the reaction was mediated by TBAF. The results have been discussed in detail by structure and transition state analysis.
Further study on the synthesis of F‐containing porphyrins and their catalytic activity on oxidation of cyclohexene
Authors: Huang Wei‐Yuan , Ying Wei‐Wen , Ma Wu‐Ping 
Published: September 2010

AbstractReaction of tetrakis(p‐allyloxyphenyl)porphyrin and perfluoroalkanesulfonyl bromides gives tetrakis(p‐polyfluoroalkoxylphenyl) substituted porphyrins. The yields are over 90%. The synthesis of the metal ion complexes of these F‐containing porphyrins is also reported. Preliminary results on the study of the catalytic activity of the manganese(III) complexes of various fluorinated porphyrins on oxidation of cyclohexene indicate that the introduction of RF group into porphyrin contributes to the stability of the catalysts.
Valence bond description for structures of O3, SO2 and NO
Authors: Wu Wei , Mo Yi‐Rong , Zhang Qian‐Er 
Published: September 2010

AbstractA modern valence bond approach, namely bonded tableau unitary group approach, is applied to ozone, sulphur dioxide and nitrite systems, respectively. It is shown that the biradical structure is in the primary position in describing the molecular structure of ozone. Thus three instead of two resonance structures are needed to describe the ground state of ozone. The case of sulphur dioxide is similar to that of ozone. It is found that, however, for the nitrite anion four resonance structures are needed.
An analysis of the rate of isomerization in molecules with an asymmetric double well potential
Authors: Zhao Meishan 
Published: September 2010

AbstractThe classical theory of the rate of unimolecular isomerization developed by Gray and Rice as extended by Zhao and Rice is applied to the calculation of the rate of isomerization in model systems which have linear asymmetric double well potentials. We are interested in this system for two reasons. First, we are interested in the detailed dynamical processes for the mentioned system because it is widely related to practical chemical reactions. Second, the present model system has an asymmetric double well potential, which provides a different test of the accuracy of the approximations used in the Gray‐Zhao‐Rice theory than posed by previous applications. We have calculated relaxation rates and relaxation times for the model systems on different time scales. We find that for the systems under studies the Gray‐Zhao‐Rice version of the classical theory of isomerization rate yields values in good agreement with those generated from trajectory calculations and from the Reactive Island theory of De Leon et al.
The synthesis of pillared nickel‐substituted saponite and its hydroisomerization activity
Authors: Jiang Da‐Zhen , Sun Tie , Liu Zi‐Yang , Min En‐Ze , He Ming‐Yuan 
Published: September 2010

AbstractNickel‐substituted saponite clays (NiS) were synthesized. The pillared clays noted PNiS were prepared from the NiS intercalated with large inorganic cations such as [Al13O4(OH)24·(H2O)12]7+. It is found that the pillar density is correlative with aluminium content in the tetrahedral sheet of NiS. The results from TPR indicate that the palladium loaded on samples promotes the reduction of the nickel ion in the octahedral sheet. The pillared clays impregnated with Pd2+ noted PdPNiS show excellent hydroisomerization property which is much better than that of nickel substituted mica‐montmorillonite pillared with silicon oxide oligomer noted PdPSMM. The hexane conversion increases with the content of aluminium ion in the tetrahedral sheet, whereas the change of the selectivity of isomerization is not obvious.