bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and magnetic properties of μ‐phenolato copper (II) binuclear complexes with different exogenous bridges
Authors: Cheng Peng Yan , Liao Shi‐Ping , Bai Dai‐Zheng , Jiang Ling‐Jim , Wang Zong‐Hui , Geng‐Lin
Published: September 2010

The syntheses and magnetic properties are reported for a series of copper(II) complexes prepared from a pentadentate binucleating ligand 2,6‐diformyl‐4‐methylphenol di(benzoylhydrazone) (H3L). These complexes incorporate different exogenous ions (X−) into a bridging position to form copper(II) binuclear complexes of the formula [Cu2(H2L)X]2+, where X− = Br−(1), Cl−(2), HO−(3), C2H5O−(4) and C3H3N−2(5). The complexes have been characterized with variable temperature magnetic susceptibility (4.2–300 K) and the observed data were fit to those from a modified Bleaney‐Bowen equation by least‐squares method, giving the exchange integral 2J = ‐6.2 cm−1 for 1, ‐76.4 cm−1 for 2, ‐241.9 cm−1 for 3, ‐231.1 cm−1 for 4 and ‐343.8 cm−1 for 5. This suggested that there is an antiferromagnetic interaction between the Cu(II) ions and the sequence of the effect of some exogenous bridging Uganda on magnetic coupling is corresponding to that in spectrochemical series.
The synthesis and crystal structure of metal complexes S‐alkyl‐N‐(ferrocenyl‐1‐methylmethylidene)‐dithiocarbazate and the study on their quenching the luminescence of ruthenium(bipyridine)23+
Authors: Duan Chun‐Ying , Xia Xu‐Bing , Zhu Long‐Gen , You Xiao‐Zeng , Yang Yao , Wang Hua‐Qin
Published: September 2010

The cobalt, nickel, copper, zinc and cadmium complexes of S‐methyl‐N‐(ferrocenyl‐1‐methyl‐methylidene)‐dithiocarbazate (H‐LSM) and S‐benzyl‐N‐(ferrocenyl‐1‐methyl‐methylidene)‐dithiocarbazate (H‐LSB) were synthesized and the crystal structure of Cd[Fe‐C(CH3) = NNCSS‐(CH3)]2 was solved by X‐ray diffraction. The crystal is in the orthorhombic system with space group Pbca, cell parameters a=19.741(3), b=19.924(5), c=15.452(4) Å, and the final factors of R=0.032. The study on quenching the luminescence of Ru(bpy)2+3 by those complexes showed that bimolecular quenching constants obtained from the Stern‐Volmer constant and the excited‐state lifetime were related to the redox potential of the quencher. Linear relationship is shown in the plot of logkq vs. E1/2(Q+/Q). The main factor which influences the quenching rate constant and the redox potential is the coordinating ability of the metal in the complex.
Properties of lysine‐containing zinc amino acid mixed complexes and evaluation of their zinc supplying ability
Authors: Huang Zhong‐Xian , Cheng Chang , Dai Xiao‐Yin , Wang Yun‐Hua , Liu Yu‐Liang
Published: September 2010

Zinc deficiency is one of the serious problems of trace element nutrition in the world, which causes a series of pathologic effects. Based on the principles of bioinorganic chemistry, the ternary complexes of Zn‐lysine‐histidine were studied as a substitution of zinc sulfate for zinc supplementation. It has also been proved by animal trail.
Intramolecular O→Sn coordination in (Z)‐1‐(triphenylstannyl)‐3‐phenyl‐1‐buten‐3‐ol: Evidence by X‐ray diffracation analysis and bromination
Authors: Fu Fang‐Xin , Fu Yu‐Jie , Zhu Dong‐Sheng , Fang Qun‐Xin , Pan Hua‐De , Lin Yong‐Hua , Jin Song‐Chun
Published: September 2010

The synthesis and properties of (Z)‐1‐(triphenylstannyl)‐3‐phenyl‐1‐buten‐3‐ol (1) are described. Compound 1 crystallizes from alcohol in the monoclinic space group P21/c with unit‐cell dimensions a=9.296(2), b=14.081(3), c=18.390(5) Å, β=97.70(2), V=2385.5(1) Å3, Z=4, F(000)=1008, Dc=1.38 g.cm−3, μ=10.88 cm−1, final R=0.0359 for 3079 observed reflection [I > 3σ(I)]. The X‐ray diffraction analysis of this compound shows the presence of an intramolecular coordination to the tin atom giving rise to a five‐membered ring in which the metal exhibits a distroted trignoal bipyramidal geometry; as a consequence, a phenyl group, probably the apical one, is cleaved more easily by bromine than the vinyl substituent.
Localized molecular orbital studies on B4Cl4, 1,5‐C2B3H5 and BH2‐(n = 6–10, 12)
Authors: Chen Zhi‐Da , Liu Chun‐Wan , Lu Jia‐Xi
Published: September 2010

The wave functions, level energies and Mülliken population analysis of localized molecular orbitals (LMO's) for B4Cl4, 1,5‐C2B3H5 and the closo‐BnH2‐n (n = 6–10, 12) are calculated by using the Edmiston‐Reudenberg energy localisation scheme under the CNDO/2 approximation in order to reveal the nature of quasi‐aromaticity of the closo‐BnH2‐n (n > 5). It has been found that all the B‐H or B‐Cl LMO's are highly localised between the B and H (or Cl) atoms, corresponding to B—H or B—Cl σ‐bond, while the Bn framework bonding is formed mainly by the three‐centered two‐electron B‐B‐B bonds on the polyhedral faces. In the cases of B4Cl4 and 1,5‐C2B3H5, these three‐centered B‐B‐B bonds just fill their polyhedral faces; however, for the framework bonding of the closo‐BnKn2‐ (n > 5), the valence electron deficiency leads to the delocalisation of their three‐centered B‐B‐B bonds, and as delocalisability of this three‐centered B‐B‐B bond increases, some three‐centered B‐B‐B bonds are farther delocalized to become a four‐centered B‐B‐B‐B bond. It is important that for the closo‐BnHn2‐ (n > 5), the sequence of this delocalisability of the three‐centered B—B—B bond is consistent with the degree of quasiaromaticity of the closo‐boranes.
Influence of vanadium doping on the behavior of YBa2Cu3O7‐y
Authors: Meng Jian , Ren Yu‐Fang , Li Xiao‐Guang , Popov V. V. , Repin S. M. , Smirnov I. A.
Published: September 2010

YBa3Cu3‐xVxO7‐y(x=0, 0.1, 0.2, 0.3, 0.4, 0.S and 0.6) superconductors have been prepared. X‐ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected at an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)—O planes. The introduction of the high valence element, vanadium, produces the extra free‐electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of =YBa2 Cu3‐xVO7‐y and also results in a depression of TC.
Synthesis and characterization of a new Mo‐Fe‐S cluster compound containing MoO3S3unit and mixed‐valent Mo atoms [Et4N]2[Mo2Fe(CO)4(S,O‐C6H4‐1,2)3Cl2]
Authors: Zhuang Bo‐Tao , Lan An‐Jian , He Ling‐Jie , Huang Liang‐Ren
Published: September 2010

Reaction of [Mo3(CO)7(S,O‐C6H4‐1,2)3]2‐ with FeCl2in MeCN at 60°C affords a new Mo‐Fe‐S cluster complex containing MoO3S3unit and mixed‐valent Mo atoms, [Et4N]2[Mo2Fe(CO)4(O,S‐C6H4‐1,2)3Cl2] (1). 1 is characterized by elemental analysis, IR, Mössbauer spectra, X‐ray photoelectron spectra and mass spectra. And the structure of 1 is suggested as the structure which contains a [Mo(S,O‐C6H4‐1,2)3] unit of which the two of three sulfur atoms link to a Mo(CO)4‐moiety and the three oxygen atoms are coordinated to a FeCl2ligand.
Synthesis and X‐ray crystal structure of oxamido‐bridged heterobinuclear Ni(II)‐Cu(II) complexes
Authors: Wei Ping‐Rong , Jia Lu , Liu Chang‐Rang , Fan Yao‐Ting , Gao Song
Published: September 2010

The two complexes [Ni(oxen)Cu(L)2](ClO4)2·H2O (L=2,2'‐bipyridyl(bpy), 1,10‐phenanthroline(phen)) have been synthesized, where oxen is N,N'‐bis(2‐aminoethyl)oxamido dianion. The crystal structure of [Ni(oxen)Cu(bpy)2](ClO4)2°CH3OH has been determined by X‐ray diffraction method. The crystal is triclinic system, space group P with a=12.179(l), b=12.298(2), c=11.476(2) Å, a=97.57(l), β=97.52(1), γ=80.29(2)°, V=1669.04(67) Å3, Z=2, D=1.667 g/cm3. The structure has been refined to final R of 0.076 and Rw of 0.080, respectively. The complexes have an extended oxamido‐bridged structure and consist of Ni(II) ion in a square planar environment and Cu(II) ion in a distorted octahedral environment.
Determination of the apparent standard potential of the Dy/Dy(III) system in the LiCl‐KCl eutectic
Authors: Chang Kai‐Guo , Lu Xiang‐Ping , Du Fu‐Ying , Zhao Min‐Shou
Published: September 2010

The apparent standard potential of Dy/Dy(III) system in the LiCl‐KCl eutectic has been determined by the logarithmic analysis of the semi‐integrals of voltammograms, logarithmic analysis of chronopotentiograms and the open circuit potentiometry. The dysprosium equilibrium potentials for various concentration of dysprosium chloride in the LiCl‐KCl eutectic melt between 400–500°C were first determined experimentally, and the apparent standard potential of this system and its temperature dependance have been calculated.
The reaction of perhalofluoroalkanes with sodium hydrogen sulfite or sodium dithionite in the presence of triethylamine
Authors: Huang Wei‐Yuan , Liu Jin‐Tao , Xie Yin‐Bao , He Xian‐Qi
Published: September 2010

Hydrodehalogenation or hydrosulfonate‐dehalogenation products, hydrohalofluorocarbons or 2‐hydropolyhalofluoroalkanesulfonates, were formed respectively from the title reaction under mild condition in good yield.
Thermocontrolling ion permeation through binary component membrane composed of crown ether liquid crystal/PVC
Authors: Qin Jun , Xie Ming‐Gui , Jiang Qing , Zhao Hua‐Ming , Liu Sheng‐Chong , Tao Chang‐Yuan
Published: September 2010

In view of the nature of orderness in structure and the mesomorphism in property of liquid crystal, the function of which is further exploited by integrating it with the feature of crown ether. The monoarmed crown ether liquid crystals are successfully applied to the imitation of biomembrane transport. Binary component membrane composed of crown ether liquid crystal and PVC was first developed. Such a novel model of biomimetic membrane is capable of imitating ingeniously the thermocontrolling transport of biomembrane, thus the essential function of liquid crystal in membane transport is more fully exploited. It was suggested, consequently, that the molecules of the crown ether liquid crystal could assemble themselves to form ionic channels, as they exist in mesophase.

Of still more significance is that the thermocontrolling transport of ions through the membrane is found to be operative selectively and the permeation of ion is under the direct influence of the thermal turmoil of the crown ether liquid crystal molecules as substantiated by the values of Arrhenius thermodynamic parameters, activation energy, Ea, and logarithmic Arrhenius constant, log A, in ion transport. Based on the aforementioned it is suggested that diffusion of ions is a rate determing step and change of rate of ion transport is varied in different phase. Influence of magnetic field on transport rate is investigated. On basis of above experimental findings, a dynamical equation of ion transportation is established which is applicable for the membrane system in general on one hands and expound the ion transport mechanism through the membrane on the other.
Structures of silylenoids and effects of metallic and haloid atoms on their stability
Authors: Feng, Sheng‐Yu , Feng Da‐Cheng , Deng Cong‐Hao
Published: September 2010

The structural characteristics of silylenoids, H2SiMX, where M = Li or Na and X = F or Cl, have been studied by ab initio calculations. H2SiMX can be represented as adducts of silylene H2Si with alkali metal halogenides, MX. The associative energies at different calculational levels of various structures of H2SiMX are given. Effects of metallic and haloid atoms on the stability of various structures of H2SiMX are also discussed in this paper.
II conjugation in the butadiene
Authors: Mo Yi‐Rong , Wu Wei , Zhang Qian‐Er
Published: September 2010

The π electronic delocalization in trans‐C4H6 and cis‐C4H6 has been investigated in the frame of ab initio valence bond theory with 6–31G basis set. The result shows that the Csp2‐Csp2 single bond length (1.506 Å) is only about 0.024 Å shorter than the Csp3‐Csp3 bond, thus the central bond length shortening would be mainly due to π conjugation. The theoretical resonance energies of the trans‐C4H6 and cis‐C4H6 are 8.48 and 7.44 kcal/mol, respectively.
Reactions of [Et3NH][(μ‐CO)(μ‐RS)Fe2(CO)6] with acetylenes. Synthesis of (μ‐σ,π‐p‐MeC6H4CCHPh)(μ‐RS)Fe2(CO)6 and (μ‐σ,π‐PhCCHC6H4Me‐p)(μ‐RS)Fe2(CO)6. The crystal structure of (μ‐σ,π‐p‐MeC6H4CCHPh)(μ‐tBuS)Fe2(CO)6
Authors: Song Li‐Cheng , Hu Qing‐Mei , He Jun‐Ling , Wang Ru‐Ji , Wang Hong‐Gen
Published: September 2010

The reactions of [Et3NH][μ‐CO)(μ‐RS)Fe2(CO)6] (1a‐d) (RnPr, nBu, tBu, Ph) with p‐MeC6H4C°CPh or m‐NO2C6H4C°CPh were studied and products of the vinyl type (μ‐σ,π‐p‐MeC5H4CCHPh)(μ‐RS)Fe2(CO)6 (2) and (μ‐σ, π‐phCCHC6H4Me‐p) (μ‐RS)Fe2(CO)6 (3) (RnPr, nBu, tBu, Ph) were obtained. While the structures of all the compounds 2a‐d and 3a‐d were characterized by elemental analysis, IR, 1H NMR and MS spectroscopies, the single‐crystal structure of 2c(RtBu) was determined by X‐ray diffraction method. The X‐ray diffraction result of 2c showed that the substituted vinyl ligand p‐MeG6H4CCHPh bridges the two iron centers, being σ‐bonded to one metal through the olefinic carbon attached to p‐MeC6H44 group, while π‐bonded to the other via olefinic linkage; the Fe2(CO)6 and proton units are in a cis fashion and the tBu group is bonded to sulfur atom through an e‐type of bond.
Synthesis and mesomorphic behaviour of 4′‐methoxyphenyl 4″‐[(4‐n‐alkoxy‐2,3,5,6‐tetrafluorophenyl)ethynyl]benzyl ethers
Authors: Wen Jian‐Xun , Yin Hui‐Yong , Tian Min‐Quan , Cheng Qi
Published: September 2010

A novel homologous series of 4′‐methyoxyphenyl 4″‐[(4‐n‐alkoxy‐2,3,5,6‐tetrafluoro‐phenyl]benzyl ethers have been prepared via Pd‐catalysed Heck reactions. Polarizing microscopic textural observation shows that these compounds exhibit enantiotropic nematic phases.
New conducting polythiophenes containing substituted polyfluorinated alkoxy chain
Authors: Zhang Xu‐Qing , Shen Xue‐Ming , Yang Shi‐Yong , Zhang Jing‐Yun
Published: September 2010

A series of poly(fluoroalkoxy thiophenes) have been prepared by electrochemical and chemical polymerization respectively. The substitution of thiophene by poryfluorinated alkoxy chains affords more favorable structures in electronic effect and higher stabilities of their polymers than conventional alkoxy chain substituted polymers.
Synthesis and bioassay of all four stereoisomers of (2E,4E)‐4,6,10,12‐tetramethyl‐2,4‐tridecadien‐7‐one, the assignment of the absolute configuration of the sex pheromone of Matsucoccus matsumurae Japanese pine bast scale
Authors: Lin Guo‐Qiang , Xu Wei‐Chu , Qi Yun‐Tai , Chen Guo‐Min
Published: September 2010

A facile enantioselective synthesis of all four stereoisomers of (2E,4E)‐4,6,10,12‐tetramethyl‐2,4‐tridecadien‐7‐one (1) is described. The stereochemistry at 6‐C and 10‐C of 1 was constructed by using optically active citronellal as starting material and by the asymmetric crotylic metal reaction. In the bioassay and field tests, only la, i.e. (6ii,10ii)‐l was active. The other three isomers 1b (6S,10R), 1c (6R,10 S) and 1d (6S,10S) were inactive. Therefore, the naturally occurring pheromone was assigned as (6R,10R)‐1.
Scanning electrochemical microscopy –‐ development of instrumentation utilizing piezo‐bimorph X‐Y scanners
Authors: Mao Bing‐Wei , Mu Ji‐Qian , Zhug Xiang‐Dong , Feng Zu‐De , Yan En‐Rou , Pan Guo‐Bin , Xie Zhao‐Xiong , Ren Bin
Published: September 2010

The development of the instrumentation of a scanning electrochemical microscopy (SECM) is presented. The core of the SECM sensing system is constructed based on piezo‐bimorph scanners, a mechanical micropositioner of multi‐dimensional adjustment and ultramicroelectrodes. The control of the electrochemical cell and the SECM system is realized by a battery powered bipoteniostat and analog control circuits respectively with the control of a microcomputer work station. The demonstrations of SECM experiments are given on both a standard IDA sample and a silver electrode. Discussions on the resolution and quality of SECM image are made.
Effects of liquid crystal states on photovoltaic effects of chlorophyll‐a
Authors: Han Yun‐Yu , Zhou Rui‐Ling , Yang Yu‐Guo , Zhou Wu , Ruan Xiao‐Lan
Published: September 2010

The photovoltaic effects of chlorophyll‐a(chla) and the effects of stearic acid, egg phosphatide and cholesterol on those were investigated by means of measuring the photoinduced potentials of SnC2/chla electrodes. Because of the formation of liquid crystal states, appropriate concentrations of stearic acid and egg phosphatide added in a certain system could increase the photovoltaic effects of chla. Cholesterol always decreased the photovoltaic effects of chla because there was no liquid crystal state formed with it.
The effects of alkali metal(Na+,K+) on the exchange degree of Hβ zeolite and the catalytic properties of the alkalized zeolites
Authors: Shen Jian‐Ping , Ma Jun , Sun Tie , Jiang Da‐Zhen , Min En‐Ze
Published: September 2010

The effects of alkali metals (Na+,K+) on the exchange degree of Hβ zeolite under different conditions and the conversion of α(or β)‐methylnaphthalene over the alkalized zeolites were studied. The results showed that the H+ of Hβ zeolite is totally replaced by the Na+ of NaCl solution, while partially exchanged by the K+ of KCl solution, there is an exchange equilibrium between the H+ and K+ for Hβ zeolite (Si/Al=17.23) and the value of equilibrium is 88.39. The exchange degree also increases with increasing the Si/Al of the samples. It was suggested that these results are attributed to the electrostatic field in the pore of Hβ zeolite and the nature of zeolite and the properties of alkali metal. The isomerization of α(or β)‐methylnaphthalene is the main reaction over the samples and it is more favour on the proper acid‐base sites of KHβ zeolite.
Effect of intramolecular energy transfer on the rate of unimolecular isomerization: HCN⟷HNC
Authors: Zhao Mei‐Shan
Published: September 2010

This paper reports calculations of the rate of isomerization of HCN→HCN based on the theory of Gary and Rice as extended by Zhao and Rice. The major task is to determine the effect of intramolecular energy transfer on the prediction of the rate of isomerization. Both the full three‐dimensional (3D) system and the reduced two‐dimensional (2D) system obtained from freezing CN bond at 1.159 A are analyzed to check the validity of the freezing bond approximation. Meanwhile, RRKM rates are calculated to test RRKM choice of the transition state by comparing to Gary‐Rice three‐state model. The comparison shows that the rates from 2D model and 3D model are differing up to 20% with 2D rates consistently larger. The intramolecular energy transfer modifies the isomerization rate for HCN system up to 30% that is modestly small by the expectation. The isomerization rate predicted from RRKM theory is greater than those of Gary‐Rice three‐state model theory up to 65%, and it overstimates the rates under all considerations, including the contribution from intramolecular energy transfer, for the studied system by about a factor of 2.
Peptide synthesis using pentafluorophenyl diphenylphosphate (FDP) as coupling reagent
Authors: Chen Shao‐Qing , Xu Jie‐Cheng
Published: September 2010

Comparison of the reaction speed and yield with its analogues and some conventional peptide coupling reagents, pentafluorophenyl diphenylphosphate (FDP) was shown to be a more preferable “active ester” type reagent for the peptide synthesis. The synthesis of oligopeptides using FOP was achieved with high yields. The influences of several reaction parameters such as solvent, base, additive and temperature on the coupling reaction were studied using HPLC method. The degree of racemization with FDP determined by HPLC or Young test was shown to be lower than that of DCCI. Octapeptide Gly‐Cys(Bzl)‐Ser‐Gly‐Lys‐Leu‐Ile‐Cys(Bzl)‐OH, corresponding to the amino acid sequence of gp41 of HIV‐1, was successfully synthesized by 5+3 approach using FDP with high yield.
Nonadiabatic collision model calculations of ion‐pair formation cross sections of Cs+O2→Cs++O
Authors: Cai Zheng‐Ting , Mu Yu‐Guang , Cong‐Hao Den G.
Published: September 2010

This paper has improved Hickman's nonadiabatic collision model by substituting Hickman's constant velocity classical straight line trajectory approximation with the solution of motion equation mR=−dV(R)/dR, and has calculated the cross sections of ion‐pair formation Cs+O2→Cs++O−2 with the improved nonadiabatic collision model (INCM). A comparison of our results with other theoretical and experimental results has been made.
Studies on monodispersed colloidal particles of doped yttrium compounds
Authors: Deng Hong‐Mei , Xu Yan , Gu Yi‐Dong
Published: September 2010

Monodispersed particles of doped yttrium basic carbonates were prepared at aging at elevated temperature corresponding salts solutions in the presence of urea. Coprecipitation in mixed solutions of yttrium, lanthanum and neodymium salts under similar experimental conditions yielded composite particles of basic carbonates. The content of the three metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so‐prepared powders were characterized by various techniques.
Surface acoustic wave sensor system applied to the kinetic study of urease in plant seeds
Authors: Liu De‐Zhong , Chen Kang , Ge Kai , Me Li‐Hua , Yao Shou‐Zhuo
Published: September 2010

A new type of the surface acoustic wave (SAW) sensor system was delivered. Urease from several kinds of plant seeds was extracted with different extracting solvents. The urease activity, Michaelis constant and other kinetic parameters were estimated for the first time by means of the new device–‐SAW sensor system. Some factors such as pH, temperature, activators and inhibitors are also discussed. The method can be applied to the determination of urea content in human urine and the experimental results consist with those reported.
Red yeast catalyzed amination of olefinic bonds and synthesis of optically pure S‐amino acids
Authors: Zhao Jian‐Shen , Yang Shun‐Kai
Published: September 2010

By using red yeast (Rhodotorula rubra AS 2.166) resting cells which possess the phenylalanine ammonia‐lyase (PAL, EC 4.3.1.5) activity as biocatalyst, enantiomerically pure S‐3‐(2‐chloro‐phenyl) alanine (2a) and S‐3‐(3‐hydroxyphenyl) alanine (2d) have been synthesized from the corresponding 3‐aryl substituted acrylic acid (1a and 1d) and ammonia.
Large scale synthesis of oligoribonucleotides on PEG by the phosphite triester approach
Authors: Xu Zu‐Sheng , Yang Zai‐Wan , Wang Yu
Published: September 2010

Large scale synthesis of oligoribonucleotides has been successfully performed on PEG support by the phosphoramidite approach using t‐butyldimethylsilyl to protect the 2'‐hydroxyl group of ribonucleoside. By means of this procedure, the dodecamer r(AGUGGUCUUUGU) was synthesized in 98.1% average coupling yield, and 55 mg pure product was obtained from one gram of functionalized PEG.
Atemoyacin A: A new bis‐tetrahydrofuranyl annonaceous acetogenin from Annona atemoya H.
Authors: Chen Wen‐Sen , Yao Zhu‐Jun , Zhang Yi‐Bin , Xu Yong‐Zhen , Wu Yu‐Lin
Published: September 2010

Atemoyacin A, a new annonaceous acetogenin was isolated from the alcoholic extract of the seeds of Annona atemoya Hort (Annonaceae). Its structure and relative configuration were elucidated on the basis of the spectral analysis.
Exact quantum and TST‐CEQ study of the collinear reaction O+HCl
Authors: Ju Guan‐Zhi , Chen De‐Zhan
Published: September 2010

Exact quantum calculations of reaction probabilities have been carried out using hyperspherical coordinates for the collinear reaction O+HCI(v ⩽1) → OH(v′⩽1)+Cl. A generalized LEPS potential energy surface with a barrier height of 8.12 kcal/mol has been used in the calculations. According to the calculated results we found that (1) the reaction probability oscillates with energy, (2) the reaction probability shows vibrational adiabaticity, although it is poorer than that for symmetric reaction Cl + HCl. The analysis of resonance has also been done. The reaction rate constants and average cross sections have been calculated by TST‐CEQ method. The rate constants are in agreement with that by QCT and smaller than the experimental one. Finally, the threshold has been estimated and is in good agreement with that of the literature.
Synthesis and characterization of trisubstituted heteropolytungstogermanates containing group 3A elements
Authors: Meng Lu , Liu Jing‐Fu , Wu Yi‐Jie , Xiao Yan‐Wen , Zhao Da‐Qing
Published: September 2010

Six new compounds, α,β‐KaHb,[GeW9M3(H2O)3O37] xH2O(M = Al, Ga, In; a + 6 =7) and α‐K9H5[Ge2W18Ga6(H2O)3O74]·20H2O, were synthesized from the lacunary precursors a and β‐GeW9O10−34 and characterized by elemental analysis, spectroscopy and electrochemistry. Tungsten‐183 NMR spectra of the title complexes consist of two lines with intensity ratio 2:1 as expected for trisubstituted heteropoly anions. The intensity ratio of α‐Ga compound is 1:2, which is different from others(2:1). With the help of FAB mass spectrum, we concluded that it is a dimer with D3h structure in aqueous, and the others exist by monomers with C30 structures.
A new strategy for the stereoselective synthesis of 2,3‐dideoxy‐3‐fluoro‐D‐ribofuranose derivatives
Authors: Guo Zhong‐Wu , Huang Bao‐Guo , Xiao Wen‐Juan , Hui Yong‐Zheng , Stanley A.
Published: September 2010

The important intermediate for syntheses of various anti‐HIV nucleoside analogues, methyl 2,3‐dideoxy‐3‐fluoro‐6‐O‐(p‐methylbenzoyl)‐α‐D‐ribofuranoside, was synthesized starting from 2‐deoxy‐D‐ribose in 5 steps with an overall yield of 24%. This strategy can be also used for synthesizing other analogues with various substitutions at 3‐C position.
Direct synthesis of per(poly)fluoroalkylmethyl‐substituted electrophilic cyclopropane derivatives
Authors: Chen Jian , Hu Chang‐Ming
Published: September 2010

A convenient and direct per(poly)fluoroalkylmethyl‐introducing cyclopropanation reaction was described. In the presence of CrCl3/Fe, per(poly)fluoroalkyl iodides reacted with diethyl allylmalonate and its analogs to give per(poly)fluoroalkymethyl‐substituted electrophilic cyclopropane derivatives in high yields. This reaction was considered to proceed by two steps: radical addition followed by cyclopropanation.
Lipases catalyzed acetylation of meso‐2,4‐dimethyl‐1,5‐pentanediol and the synthesis of Prelog‐Djerassi lactone
Authors: Lin Guo‐Qiang , Xu Wei‐Chu
Published: September 2010

Lipase catalyzed acetylation of 2 afforded 3 with the e.e. up to 98%. Utility of 3 was illustrated by the preparation of Prelog‐Djerassi lactones 7a and 7b.
Dynamical studies of the reaction H++He+He→HHe++He
Authors: Yu Hua‐Gen
Published: September 2010

The classical trajectory method is employed to calculate the rate coefficient kr for the reaction H ++He+He→HHe+ + He at the temperatures ranging 200–350 K, based on an ab initio potential energy surface. The results show that kr is strongly dependent on the temperature, which can be well fitted by the function kr=ATDr‐3 with A=4.192×10−31 cm6/s and the reaction dimension Dr=2.706. The product molecules HHe+ are found in high vibrational states.
Enantiomeric separation of α‐phenylethylamine and its derivatives by series coupled open tubular columns
Authors: Zhou Liang‐Mo , Liu Xue‐Liang , Li Zhong‐Sheng , Wang Qing‐Hai , Zhu Dao‐Qian , Hu Dong‐Hong
Published: September 2010

A series coupled fused‐silica open tubular columns of a chiral and an achiral stationary phase were used to achieve the enantiomeric separation of a‐phenylethylamine, o,m,p‐methyl‐ and o,m,p‐methoxy‐α‐phenylethylamine. A simplified equation describing the retention values of series coupled columns was derived, which relates the capacity factors of series coupled columns to the capacity factor of individual columns, their lengths, inlet and outlet pressure. Very good agreement was obtained both between calculated values by this equation and those by Krupcik's equation and between values measured experimentally and calculated theoretically. By means of this simplified equation a computer program was developed in locating the operating range of optimum αmin, enantiomeric separation of all α‐phenylethylamine and its derivatives were achieved in a single run.
Synthesis of dimethyl 3‐perfluoroalkyl‐4‐(3‐oxo‐2‐triphenyl‐phosphoranylidenbutanylidene)‐pent‐2‐enedioate and its cyclization
Authors: Ding Wei‐Yu , Cao Wei‐Guo , Yao Yuan , Zhu Zhong‐Mei
Published: September 2010

The title compounds 5a–‐5c were prepared via the reaction of methyl 2‐perfluoroalkynoates (4) with methyl 5‐oxo‐4‐(triphenylphosphoranylidene)hex‐2‐enoate (3), which was obtained from the reaction of methyl propynate (2) with acetylmethylenetriphenylphosphorane (1) at–‐5–0°C. Intramolecular elimination of Ph3PO took place when compound 5 was heated in aqueous methanol at 115–120°C in sealed tube, yielding dimethyl 2‐trifluoromethyl‐4‐methylisophthalate (6a) from 5a and methyl 5‐acetyl‐4‐hydroxy‐2‐heptafluoropropanylbenzoate (6b) from 5b, respectively. The structures of compounds5, 6a and 6b were confirmed by IR, MS, 1H NMR, 19F NMR and 13C NMR spectroscopy and elemental analyses. Reaction mechanisms for the formation of compounds5, 6a and 6b were proposed.
Isomeric structures, isomerization and decomposition of silylenoids H2SiMX (MXKF, KCl, LiBr, NaBr and KBr)
Authors: Feng Da‐Cheng , Feng Sheng‐Yu , Deng Cong‐Hao
Published: September 2010

The isomeric structures, isomerization and decomposition of silylenoids H2SiMX (MXKF, KC1, LiBr, NaBr and KBr) have been investigated by ab initio molecular orbital theory. These silylenoids have four kinds of very similar equilibrium structures. The three‐membered ring and p‐complex structures should be stable and experimentally detectable. The lifetime of σ‐complex and tetrahedral structures would be very short and experimentally undetectable.
Theoretical studies on the mechanism of the thermal decarboxylation and decarbonylation of a number of α‐keto‐acids
Authors: Chen Li‐Tao , Chen Guang‐Ju , Fu Xiao‐Yuan
Published: September 2010

Both processes of decarboxylation and decarbonylation of a number of acids including RCOCO2H, RH, CH3, CH2F, CF3, CHCH2, Ph, OH have been studied by semi‐empirical MO theory AM1 method to verify the reaction mechanism of each process and the effect of different substituents on them. The calculated results are consistent with the experimental reports and can be summed up as follows: (1) The decarboxylation of these acids to form aldehydes and carbon dioxide is concerted and takes place through a 4‐membered ring transition state in which a partial negative charge develops on the carbon of the α‐carbonyl group, so that the inductive effect of some substituents is favourable for this process. (2) Their decarbonylation into carboxylic acids and carbon monoxide however is the attack of the OH on the carbon of the alkyl portion of the acid, forming a 3‐membered ring transition state. (3) The activation energy of decarbonylation is lower than that of decarboxylation, since oxygen is more nucleophilic than hydrogen and also the strong OH bond need not to be broken.
STM image of tungstosilicic acid molecular layer on highly oriented pyrolytic graphite
Authors: Zhang Bai‐Lin , Wang Er‐Kang
Published: September 2010

Molecular layer of tungstosilicic acid (H4SiW12O40) deposited on freshly‐cleaved highly oriented pyrolytic graphite (HOPG) was observed by scanning tunneling microscopy (STM) in air at room temperature. The molecular dimension (11.5 Å) of H4SiW12O40 measured by STM is consistent with known crystallographic parameter. We also imaged the boundary of H4SiW12O40 molecular layer on HOPG showing that molecular layer of H4SiW12C40 was formed. It has been proved that individual tungstosilicic acid species is imaged. The probable reason for the formation of the molecular layer is also discussed.
Synthesis and structure of tetranuclear copper(II) complex containing μ4‐oxo bridge
Authors: Zhang Wen‐Xing , Ma Chang‐Qin , Wang Xu‐Ning , Yu Zheng‐Gang , Lin Qi‐Jun , Jiang De‐Hua
Published: September 2010

A new dinucleating Schiff base ligand HL(LC13H17N2O−3) has been synthesised and characterized. The single crystal structure of its complex [L2Cu4O(AcO4)]·2H2O has been determined by X‐ray diffraction methods. The result indicates that every Cu atom has its square pyramidal coordination polyhedron and there is a tetrahedral Cu4O core in the complex molecule. Its active sites where catalytic oxidation of dioxygen occurs have been inferred.
Synthesis and characterization of adducts of p‐azidostyrene derivatives to fullerene C60
Authors: Li Ji‐Sheng , Dong Guo‐Xiao , Feng Jun , Ji Gai‐Jiao
Published: September 2010

Fullerene C60 reacted with p‐azidostyrene derivatives in refluxing chlorobenzene, yielding monoadducts 2a and 2d as well as diadduct 2c with aziridine structure at 6/6‐ring junctions. Experimental results showed that the addition of the second azide to the monoadduct was regioselective. The diadduct, of Ca symmetry in C60 moiety, was unstable by opening to be 1,6‐imido[10]annulene structure.
Synthesis, characterization and electrical conductivity of poly[ethyl trifluorobuty‐2‐noate]
Authors: Yang Shi‐Yong , Zhao Wen‐Yan , Huang Yao‐Zeng , Zhang Xu‐Qing , Zhang Jing‐Yun
Published: September 2010

Poly[ethyl trifluorobuty‐2‐noate] (PETFB) was prepared from ethyltrifluorobuty‐2‐noate by anionic polymerization. The polymer was examined by UV‐Vis, IR and NMR spectrometries. It possessed π‐conjugated backbone in the main chain. No significant variation in the electrical conductivity of BF3‐doped PETFB was observed after more than three months' storage, indicating improved conductive stability in air as compared with polyacetylene.
Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis
Authors: Zhao Yu‐Rui , Wang Xian‐Kai , Zhou Jun , Cheng Chang‐Xiang , Huang Xiao‐Lin , Wu Hou‐Ming
Published: September 2010

In the previous papers, we reported the structural elucidation of stellarins A‐E, five new cyclopeptides from the fresh roots of Stellaria yunnanensis Franch. Further chemical study on this plant led to the isolation of two other new cyclopeptides named stellarins F(1) and G(2). By a combination of 2D‐NMR, enzymatic degradation and FABMS, their structures were established to be cyclo(Gly‐Ala‐Gly‐Ser‐Pro‐Trp‐Phe‐Pro) and cyclo(Gly‐Ala‐Tyr‐Leu‐Ala), respectively.
Quantum chemistry study on B32 and B32H2–32
Authors: Feng‐Long Gu , Qian‐Shu Li , Au‐Chin Tang
Published: September 2010

The structures of B32 and B32H2–32 with Ih symmetry have been investigated by means of ab initio calculations at STO‐3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B32 (B32H2–32) and C60 (C60H60) have been inferred.
A new phosphate, KMgY(PO4)2, isostructural with xenotime
Authors: Shao‐Long Tie , Qiang Su , Ya‐Qin Yu , Jian‐Fang Ma
Published: September 2010

A new phosphate, KMgY(PO4)2, isostructural with xenotime, was firstly reported in detail. It crystallizes in tetragonal system with space group I41/amd (No. 141). The cell parameters were obtained from X‐ray powder diffraction data with a=0.6886, c=0.6025 nm, Z=2. The proposed structure of KMgY(PO4)2 was further confirmed by its vibrational spectra, IR and Raman spectra, which were also compared with those of iso‐structural YPO4.
Study on kinetics and mechanism of copper‐catalyzed oxidation of hydrazine by iron (III) in acid solution
Authors: De‐Ping Cheng , Shi‐Jun Xia
Published: September 2010

The copper‐catalyzed oxidation of hydrazine by iron(III) in acid solution follows the rate law ‐d[Fe(III)]/dt = kKh[Cu(II)]2/(Kh + [H+]), where Kh is the hydrolysis constant of Cu2+, k was found to be 8.8±0.8, 13.2±1.4 and 17.5±1.3 min−1 at 35, 40, and 45°C respectively and μ= 0.2 mol/L. The composition of the activated complex is Cu2+, CuOH+, N2H4, H+ or others. Perhaps several hydrazine complexes of Cu(II) participate in the reaction and one of them isolated was Cu(N2H4)2(HSO4)2. Study on the oxidation of this complex is also in conformity with the above rate law.
Synthesis and mesomorphic properties of n‐alkyl 4‐[4‐(4‐n‐octyloxybenzyloxy‐2,3,5,6‐tetrafluorophenyl)ethynyl]benzoates
Authors: Yue‐Lian Xu , Wei‐Li Wang , Qi Chen , Jian‐Xun Wen
Published: September 2010

A new series of n‐alkyl 4‐[4‐(4‐n‐octyloxybenzyloxy‐2,3,5,6‐tetrafluorophenyl)ethynyl)benzoates have been prepared. Polarizing microscopic textural observation shows that they are liquid crystals with nematic phase.
Synthesis of key intermediates to 20(R)‐and 20(S)‐trifluoromethyl‐23,24‐dinor‐25‐hydroxy‐cholesterol and VD3 analogs
Authors: Shou‐Fu Lu , Ben‐Fang Ruan , Zhong‐Qi Wang
Published: September 2010

Synthesis of 20(R)‐and 20(S)‐trifluoromethyl substituted steroids as the key intermediates (1a, 1b) to 23,24‐dinor‐20‐trifluoromethyl‐25‐hydroxy‐cholesterol and VD3 analogs, using trifluoromethyltrimethylsilane (CF3SiMe3) as a trifluoromethylating agent, was described.
Preparation of some new derivatives of (1R,2S)‐1,2‐diphenyl‐2‐aminoethanol and enantioselective borane reduction of propiophenone
Authors: Yao‐Zhong Jiang , Yong Qin , Ai‐Qiao Mi , Lan‐Jun Wu
Published: September 2010

Some new methylated and N‐alkylated derivatives of (1R,2S)‐1,2‐diphenyl‐2‐amino ethanol were synthesized and applied to enantioselective borane reduction of propiophenone. The relationship between catalyst structure and enantioselectivity was discussed in detail.
Direct synthesis of 3‐fluoroalkyl‐2,6‐diethoxycarbonyl phenols
Authors: Hui‐Ping Guan , Qiao‐Sheng Hu , Chang‐Ming Hu
Published: September 2010

Cyclocondensation of α‐fluoroalkyl ketones or α‐fluoroalkyl aldehyde (1) and diethyl 1,3‐acetonedicarboxylate (2) affords 3‐fluoroalkyl‐2,6‐diethoxycarbonyl‐5‐alkyl‐phenols (3) in good yields. This provides a novel method for the preparation of meta‐fluoroalkyl polysubstituted phenols.
Comparative studies on the concerted and two‐step mechanism of ketene‐methylenimine cycloaddition
Authors: De‐Cai Fang , Xiao‐Yuan Fu
Published: September 2010

The concerted reaction mechanism of the ketene‐methylenimine cycloaddition reaction was reconfirmed by IRC calculation at HF/6–31G* level. Other possible reaction schemes were also studied. The cis and gauch intermediate cannot be found on the potential energy surface, and the trans intermediate can only lead to a 6‐membered ring product. Therefore, a two step mechanism to form β‐lactam is excluded for the title reaction.
Fluorescence enhancement effect and the interaction between donor and acceptor
Authors: Pin Yang , Man‐Man Yang , Bin‐Sheng Yang
Published: September 2010

A new theoretical equation for fluorescence enhancement effect between donor and acceptor has been introduced. By using it we determined the binding constants and numbers of binding sites of five medicines, including chlorogenic acid, forsythiaside norfloxacin, Ciprofloxacin and fluorenone, to γ‐globulin.
Effect of antimony on the reduction of anodic PbO2 film on Pb‐Sb alloys in sulfuric acid solution
Authors: Wen‐Bin Cai , Yong‐Qin Wan , Hou‐Tian Liu , Wei‐Fang Zhou
Published: September 2010

The reduction processes of anodic PbO2 films formed on Pb‐Sb alloys in 4.5 mol.dm−3 H2SO4 solution at 1.4 V(vs. Hg/Hg2SO4) for 1 h have been investigated by photocurrent method, chronoamperometry, linear sweep voltammetry as well as X‐ray diffractometry. It was found that the reduction of most of the β‐PbO2 and part of the α‐PbO2 to PbSO4 can be completed within 1 s between 0.9 V and 1.0 V(vs. Hg/Hg2SO4) and proceeds much faster than that of the remaining α‐PbO2 into photoactive α‐PbOx (1 < x < 1.4). The presence of antimony in the alloy retards significantly the reduction of the remaining α‐PbO2 and decreases slightly the band‐gap energy of t‐PbO.
Reaction of amino acid derivatives with C60
Authors: Nai‐Xing Wang , Ji‐Sheng Li , Dao‐Ben Zhu
Published: September 2010

Amino acid derivatives react with C60 at 110‐120°C to form adduct compounds. The products were isolated by column chromatography and were identified by FD‐MS, UV‐Vis, FT‐IR and 13C NMR spectroscopies.
Studies on the magnetic property of μ3‐oxotriiron(III) complex [Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2 (HOBzBenzoic acid)
Authors: Guo‐Xiong Wang , Hua Zhang , Yao Chen , Tian‐Yang Yao , De‐Gang Fu
Published: September 2010

The magnetic property of μ3‐oxotriiron(III) complex [Fe3O(OBz)6(CH3OH)3](NP3)‐(CH3OH)2 (HOBzbenzoic acid) has been studied. We use isosceles triangle model and molecular field correction to fit the experimental magnetic susceptibility data. It shows that an intramolecular antiferromagnetic exchange interaction occurs with J = ‐31.27 cm−1, J'= ‐27.26 cm−1, and a weaker intermolecular antiferromagnetic exchange interaction occurs with zJ' = ‐ 3.76 cm−1. We give the d5‐d5‐d5 energy level diagram of triiron(III) complex as a function of J'/J. From the diagram we can get the total spin ST of the complex as 1/2 in the ground state.
HeI photoelectron spectroscopic (PES) studies of the electronic structure in ω‐heterocycle α‐cyano polyenic ethyl ester Compounds
Authors: Ying Li , Sheng Li , Ben‐Ming Chen , Dian‐Xun Wang
Published: September 2010

Hel photoelectron spectra of ω‐heterocycle α‐cyano polyenic ethyl ester compounds (1–6) have been given in this paper. Assignment of the spectra is also done with the aid of HeI photoelectron spectroscopic (PES) results of smaller molecules which have similar atomic group to the molecules studied, and the aid of MNDO molecules orbital calculations. The lowest PES experimental ionization potentials (IPs in eV) of different molecules reduce gradually with the increasing number of ethylenic group. The ‐CO2C2H5 group can be only considered as a substituent.
Electrochemically modified piezoelectric crystal biosensor for detection of Staphylococcus aureus
Authors: Shi‐Hui Si , Jin‐Hua Chen , Feng‐Jiao He , Li‐Hua Nie , Shou‐Zhuo Yao
Published: September 2010

Electropolymerized o‐phenylenediamine film is used as a functional coating for the immobilization of anti‐S. aureus antibody on the surface of a gold‐plated piezoelectric crystal, and this piezoelectric immunosensor is applied to detect S. aureus. The frequency shift (ΔF = F20z ‐ F380z, Hz) between the frequency at the 20th second (after the addition of sample, F20Z) and that at 380 seconds later (F380z) was introduced to construct a calibration graph, and shortening of assay time was achieved. The S. aureus concentrations in the range of 105–109 cells/mL can be detected by this system.
Spectrophotometric determination of cationic surfactants by formation of ternary complexes with Fe(III) and chrome azurol
Authors: Ming Song , Shu‐Quan Liang
Published: September 2010

An extraction‐free spectrophotometric method for the determination of cationic surfactants, such as cetylpyridinium chloride, cetyltrimethylammonium bromide and zephiramine is proposed, which is based on the formation of ternary complexes with Fe(III) and chrome azurol S. The molar ratio of the complex is 2:1:1 (Fe(III):chrome azurol S: cationic surfactant). The method is simple, rapid and sensitive, giving an apparent molar absorptivity of 4.5×104 L·mol−1‐cm−1 and a linear range of 0.1–6.0 μmol/L cationic surfactants. The total cationic surfactant content can be determined directly in aqueous solutions by measuring the absorbance at 680 nm (pH 5.8). The method has been successfully applied to water samples.
Influence of oscillator phase on oscillation frequency and sensitivity of an electrode‐separated piezoelectric Sensor
Authors: Da‐Zhong Shen , Qi Kang , Jing‐Tian Hu
Published: September 2010

Theoretical consideration was proposed for the influences of the oscillator phase on the response nature of an electrode‐separated piezoelectric sensor (ESPS) to liquid properties and verified experimentally. For the oscillators with different phases, the oscillation frequency of the ESPS may increase, maintain nearly constant or decrease with increasing conductivity in low conductivity solutions. The sensitivity of response to density and viscosity increases slightly with increasing oscillator phase. The response to permittivity depends hardly on the oscillator phase. In addition, the dependence of the oscillation frequency of the ESPS on the supply voltage of the oscillator was explained. The ESPS was used to determine atropine sulfate with a detection limit of 1.6·10–7 mol/L.
Nucleophilic reactions of l‐methyl‐2‐methoxy‐2‐phenyl‐3‐oxo‐2,3‐dihydroindole
Authors: Ke‐Qing Ling
Published: September 2010

The title compound (1) was prepared via methylene blue (MB)‐sensitized photooxy‐genation of l‐methyl‐2‐phenylindole (2d) in methanol. Acid‐catalyzed nucleophilic substitution of 1 with nucleophiles gave 1,2,2‐trisubstituted 3‐oxo‐2,3‐dihydroindoles (3–6). Reduction of 1 with lithium aluminum hydride, followed by acidic workup yielded 4d and 2d, whereas the same reduction reaction of 1, followed by neutral workup gave l‐methyl‐2‐phenyl‐3‐hydroxy‐2,3‐dihydroindole (15), together with 3. The reaction pathways of nucleophilic substitution and reduction of 1 were discussed.
Regioselective etherification of l,2‐O‐isopropylidene‐4,6‐di‐O‐benzyl myo‐inositol
Authors: Cheng‐Ye Yuan , Hai‐Xiao Zhai , Shu‐Sen Li
Published: September 2010

During the etherification of 1,2‐O‐isopropylidene‐4,6‐di‐O‐benzyl myo‐inositol, the specific regioselectivity on 3‐ or 5‐hydroxyl group was showed to be determined by the nature of the O‐ alkylating agents used. As demonstrated by MM and MNDO calculation, the regioselectivity of the reaction mentioned can be rationalized by steric and/or electronic effect.
Isolation and structural elucidation of a polysaccharide with radiation‐protective activity from Spirulina platensis
Authors: Zhong‐Wu Guo , Yong‐Zheng Hui
Published: September 2010

The structure of a radiation‐protective sulfated polysaccharide, SP‐APS, isolated from Spirulina platensis, was investigated by methylation analysis, partial acetolysis and 1H‐NMR spectroscopy. The repeating‐unit of SP‐APS as branched structures was elucidated.
Study on the reaction of triple helix poly(A:2I) with Cu2+
Authors: Er‐Bing Hua , Pin Yang , Qing‐Shan Li , Bin‐Sheng Yang
Published: September 2010

The effect of Cu2+ on the triple‐stranded helical structure of poly(A:2I) was studied by means of circular dichroism spectral method with the help of ultraviolet spectral and ethidium bromide fluorescence probe methods. It was found that Cu2+ destabilizes the structure of the triple helix poly(A:2I) and induces its structural transformations, meanwhile, the transformations can be partially reversed by a higher NaCl concentration. The structural transformations may be expressed by the following scheme: poly(A:2I)·poly(A:I) + poly (I) · poly(A) + 2poly(I)
Epoxidation of styrene catalyzed by manganese (III) porphyrins supported on chloromethylated polystyrene resin bearing crown ether groups,
Authors: Jing‐Song You , You‐Fa Xiao , Xiao‐Qi Yu , Ai‐Xia Cheng , Zhong‐Wei Lan
Published: September 2010

Metalloporphyrins and crown ether groups were simultaneously supported on chloromethylated polystyrene resin to produce a series of polymer‐supported catalysts. The synthesis of these catalysts has been studied. The influence of pH, concentrations of NaOCl and phase transfer catalysts on the epoxidation of styrene catalyzed by these catalysts has also been investigated. The experimental results show that manganese(III) porphyrin bound to chloromethylated polystyrene which bears crown ether groups is effective catalysts for the epoxidation of styrene by sodium hypochlorite. The introduction of crown ether groups increases the catalytic efficiency of supported metalloporphyrins. The kinetics of epoxidation catalyzed by supported manganese(III) porphyrins obeys Michaelis‐Menten equation—the characteristic of enzyme‐driven reaction.
Theoretical studies on the structures and reactivity of stannylenoids I. The structures and isomerization of stannylenoid H2SnLiF
Authors: Hua‐Yu Qiu , Cong‐Hao Deng
Published: September 2010

The structures of singlet stannylenoid H2SnLiF have been examined by ah initio MO theory. Four equilibrium states and three transition states of isomerization reaction are located. The calculation shows that the p‐complex 1 is the most stable and experimentally detectable. The other three species, three‐membered ring 2, s̀‐complex 3 and tetrahedron 4, are also local minima on the potential energy surface, but are higher in energy.