Preparation, Characterization and Catalytic Properties of S2O8^2-／ZrO2 Supported by Tungsten Carbide

A WC-supported S2O8^2-/ZrO2(PSZ) catalyst was prepared and characterized by means of XRD, BET, FTIR and XPS. The isomerization of n-pentane over the catalyst was investigated as well. The results show that the skeletal isomerization and the crack of n-pentane proceed simultaneously on WC-supported S2O8^2-/ZrO2 catalyst. The addition of tungsten carbide showed a significant enhancement in the activity and stability of the catalyst for n-pentane isomerization. The catalyst showed evidently a better activity than S2O8^2-/ZrO2 supported by Pt and WO3. The results can be interpreted by the existence of the tungsten oxycarbide compound(WCxOy) with carbidic, oxide and acidic sites.     

Catalytic Preparation of Optically Active 1,1′—Binaphthalene—2,2′—Diol by Chiral Benzoimidazole—Cu（Ⅱ）Complex

Inthepastseveraldecades ,muchattentionhasbeenpaidtoopticallyactive ,C2 asymmetric1,1′ bi naphthalene 2 ,2′ diolanditsderivativesbecauseoftheirapplicationininducingchiralityinasymmetricsynthesis[1,2 ] .Enantiomericallypure1,1′ binaphtha lene 2 ,2′ diolhasbeen preparedbymanymethodsrangingfromtheclassicalresolutionviacrystalliza tionofthediastereoisomericsalts[3] toasymmetricox idativecoupling[4～ 6 ] .However ,theuseofexpensivechiralreagentsandthetediousnessoftheprocessessetalimitontheuseof…     

8-羟基喹啉单体及二聚体质子转移反应的理论研究

Density functional theory （DFT） of quantum chemistry method was employed to investigate proton transfer reactions of 8-hydroxyquinoline （8-HQ） monomers and dimers. By studying the potential energy curves of the isomerization, the most possible reaction pathway was found. The total energy of 8-hydroxyquinoline was lower than that of quinolin-8（1H）-one, whereas the order was reversed in dimers. The findings explained the contrary experimental phenomena. The minimum reaction barrier of intramolecular proton transfer was 47.3 kJ/mol while that in dimer was only 25.7 kJ/mol. Hence it is obvious that proton transfer reactions of 8-HQ monomer have a considerable rate but it is easier to proceed for 8-HQ dimer than monomers. It implied that the hydrogen bond played an important role in depressing the activation energy of reaction. The mechanism of the tautomerization was discussed on the basis of theoretical results.     

配体形状对多吡啶铜(Ⅱ)配合物与DNA作用的影响

合成了一系列含有平面配体的Cu(Ⅱ)多吡啶配合物[Cu(IP)₂]²⁺、[Cu(PIP)₂]²⁺、[Cu(DPPZ)₂]²⁺和[Cu(HPIP)₂]²⁺，用吸收光谱、CD光谱和粘度等方法研究了这些配合物与小牛胸腺DNA的作用。结果表明配体上的取代基及配体的平面性对这些四面体配合物与DNA的结合强弱产生一定的影响。[Cu(DPPZ)₂]²⁺与DNA的结合较强，而[Cu(HPIP)₂]²⁺与DNA的结合较弱。CD光谱显示配合物[Cu(DPPZ)₂]²⁺、[Cu(PIP)₂]²⁺和[Cu(HPIP)₂]²⁺的加入会导致DNA的CD光谱减弱。而[Cu(IP)₂]²⁺的加入则会使DNA的CD光谱增强。同时，[Cu(IP)₂]²⁺与DNA结合后，还会引起一定程度的DNA构型转换，即DNA从B型转换成Z型。     

固载Ru基催化剂上二氧化碳加氢合成甲酸Ⅱ反应条件对催化剂性能的影响

The synthesis of formic acid from carbon dioxide and hydrogen using a silica immobilized ruthenium catalyst as precursor has been studied in different reaction conditions. The results revealed that the TOF （turn over frequency） of HCOOH achieved 1481.5 h^-1 on immobilized ruthenium catalyst near the critical pressure point of CO2 with H2 pressure of 4.0 MPa, reaction temperature of 80℃ and PPh3/Ru molar ratio of 6：1. The reaction activity of immobilized catalyst was higher than that of homogeneous catalyst, and the immobilized catalyst also offered the practical advantages such as easy separation and reuse.     

类水滑石主体层板与客体CO2-3、H2O间的超分子作用

通过构建类水滑石双层计算模型,采用混合密度泛函B3LYP/6-31G(d)//B3LYP/3-21G方法计算类水滑石(LDHs-CO3-yH2O)的结构与能量,探讨LDHs限域空间中客体阴离子及水分子的分布形态以及主客体超分子作用.计算结果表明,客体阴离子与水分子以平行层板的方式存在于水滑石层间.主客体发生作用时,CO2-3的HOMO轨道向层板的LUMO轨道转移电子.所形成的LDHs-CO3主客体作用要强于LDHs-F以及LDHs-Cl.与其离子交换性能相一致.水滑石去水结构(LDHs-CO3)水合过程,氢键作用较静电作用更占优势,并且layer-water型氢键要强于anion-water型氢键.此外,水合能计算表明LDHs水合具有一定的饱和量.     

微量元素锡与健康

随着经济的发展，锡及其化合物越来越多地用于现代生活。综述了锡对人体健康的影响，包括：锡的性质、存在，环境污染、抗癌作用以及毒性等方面。     

Synthesis and Characterization of Novel Polyimides Based on Pyridine-containing Diamine

A new aromatic diamine monomer containing pyridine unit, 2,6-bis （4-aminophenoxy- 4＇-benzoyl）pyridine（BABP）, was synthesized in three steps, starting from 2,6-pyridinedicarboxyl chloride. A series of novel pyridine-containing polyimides were prepared v/a the polycondensation of BABP with various aromatic dianhydrides through poly（amic acid） precursors, and thermal or chemical imidization of the precursors. The polyimides exhibit desirable properties, e.g., good solubility in N-methyl-2-pyrrolidone and m-cresol, excellent thermal stability and film-forming capability, as well as high inherent viscosity, indicating high molecular weight.     

Studies on Aggregation Interaction between Reduced Denatured Egg White Lysozymes during Refolding Procedure in Urea Solution

The aggregation interaction between reduced-denatured egg white lysozymes during refolding procedure in urea solution was studied by means of reducing and non-reducing protein electrophoreses. Results of non-reducing sodium dodecyl sulphate polyacrylamide gel electrophoresis （SDS-PAGE） of the supernatant and aggregate precipitate formed in refolding process show that except being refolded to native egg white lysozymes, the reduced-denatured lysozymes can also form the aggregates with molecular weights （MW） being separately about 30.0 and 35.0 kD, while the reducing SDS-PAGE and the refolding results in the presence of sodium dodecyl sulphate show that these aggregates are formed chiefly through the misconnection of disulfide bonds between the reduced-denatured lysozymes, and the aggregate precipitates are formed through the non-covalent interactions between the aggregates with molecular weight being about 30.0 kD. From the results of electrophoresis and size-exclusion chromatographic analyses, it can be inferred that the aggregates with molecular weights being about 30.0 and 35.0 kD are bi-molecular and tri-molecular egg white lysozyme aggregates, respectively. And finally, a suggested refolding mechanism of reduced-denatured egg white lysozymes in urea solution was presented.     

6-O-Sulfated Modification of Natural Glycoalkaloids Chaconine and Solanine

Introduction Glycoalkaloids(GAS)arepotentiallytoxicsecond aryplantmetabolitesfoundinpotatoes,tomatoesand eggplants[1].Someinvestigationshaveindicatedthat glycoalkaloidsmusthavebeenevolvedinnaturetopro tectplantsagainstbacteria,fungi,insects,andani mals.Th…