Na＋-丙氨酸二肽络合离子结构的密度泛函理论研究

运用密度泛函理论B3LYP方法在6-311＋＋G**基组水平下研究了Na^＋与丙氨酸二肽(AD)分子结合形成的6种Na^＋-AD 络合离子, 其中包括2种双齿结构和4种单齿结构. 考察了6种Na^＋-AD络合离子的相对稳定性, 分析了丙氨酸二肽分子与Na^＋作用过程中分子骨架Ramachandran角f和Ψ以及分子内氢键的变化.     

Si5H3,Si5H6,Si5Li3及Si5Na3原子簇结构的理论研究

利用Gaussian-94计算程序中的B3LYP方法，在6—311 G(2d)6d基组下，对Si5，Si5H3，Si5H6，Si5Li3和Si5Na33原子簇的几何结构进行优化和频率计算．结果表明，Si5原子簇中最稳定的具有D3h对称性的结构中，位于同一平面上的3个Si原子确实具有剩余的成键能力，可以与3个H，Li，Na原子和6个H原子形成稳定的化合物．研究还发现，虽然H，Li和Na都属同一主族，但它们与Si5原子簇中Si原子的键连方式却不同，而且它们的加入，对Si5原子簇的“三角双锥”结构也有不同的影响．     

The search for a new model structure of β-Factor XIIa

We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular.     

Heterogeneous catalytic aerobic oxidation behavior of Co–Na heterodinuclear polymeric complex of Salen-crown ether

A new kind of Co–Na heterodinuclear polymer complex based on Salen Schiff base and crown ether has been successfully prepared by condensation polymerization. Its catalytic behavior for aerobic oxidation of cyclohexene, alkylbenzenes and linear aliphatic olefins was studied in the absence of any solvents or reducing agents under mild conditions. The oxidation of cyclohexene catalyzed by the above catalyst proved to be a simple and efficient method for obtaining 2-cyclohexen-1-one (CO) and 2-cyclohexen-ol (OH) in a high selectivity. Kinetics of the oxidation was also investigated. The results showed that the aerobic oxidation of cyclohexene catalyzed by Salen-crown ether heterodinuclear polymer complex follows a radical chain aerobic oxidation mechanism. This oxidation system is also efficient in the oxidation of alkylbenzenes and linear aliphatic olefins, which afforded corresponding benzylic oxidation products and epoxides, respectively.     

Structure-Activity Relationship of Insecticidal Steroids. III. Δ4,7-6-Ketosteroids

The toxicity of steroids 1-11 for colorado beetle (Leptinotarsa decemlineata Say.) larvae was studied by contact-intestinal treatment. Active insect-growth regulators were found among the studied compounds.     

A new biodegradable polydepsipeptide microsphere for application in drug delivery systems

A sequential polydepsipeptide containing a tripeptide sequence L-alanyl-Lalanyl-ethyl L-glutamyl and an-hydroxy acid L-lactic acid, poly(Ala-Ala-Glu(OEt)-Lac), was synthesized to prepare the microspherical particles by the solvent evaporation process. In this case, the solvents play the most important role for the preparation of polydepsipeptide microspheres and, as an example, when 200 mg of the polydepsipeptide dissolved in 10 ml of 98/2% chloroform/dichloroacetic acid mixture was stirred at 400 rpm and 30 C, the microspherical particles with mean diameter of 58m were formed after pouring into 200 ml of 1% (w/v) poly(vinyl alcohol) solution. 17-Estradiol was incorporated into the particles, and the resulting particles were found to contain 5 mg of drug per 25 mg of the particle. The in vivo release of drug from the microspherical formulation was evaluated by measuring the pharmacological influence on rat prostate. It was found that the sufficient amount of drug, keeping the effective pharmacological influence, is supplied during the first 12-week period, followed by an incomplete supplying of drug intil the implant is perfectly degraded in vivo in the 25th week from the start of implantation.     

Boron chelates with 5,5,5-trifluoro- and 5,5,5-trichloro-4-aminopent-3-en-2-ones

Boron chelates were obtained by the reaction of butoxy(butylthio)diphenylborane with 5,5,5-trifluoro(trichloro)-4-aminopent-3-en-2-one, and their reactions with primary amines were investigated. -Diiminate complexes of boron with trifluoro- and trichloromethyl groups were synthesized.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2657–2661, November, 1992.     

Liquid chromatography of the s-triazines

Summary A series of thirty s-triazine compounds have been separated using reversed-phase high-pressure liquid chromatography. A relationship between substituent activity and retention time was developed to predict molecular structure.Work partially completed at the CIBA-GEIGY Corp., McIntosh, Ala., USA.     

Mechanistic aspects of the Wolff-Kishner reaction. V. The cation effect on the reaction of benzophenone hydrazone in butyl carbitol and decyl alcohol

The rate of the Wolff-Kishner reaction of benzophenone hydrazone in butyl carbitol increases as the cation of the alkoxide base is varied in the order K>Na>Li>Mg. The replacement of butyl carbitol by 1-decanol also accelerates the reaction, and an additional increase is caused by the presence of crown ether. On the basis of changes in the activation parameters, it is concluded that the reactivity of the hydrazone anion increases as the contact ion pair becomes more fully solvated and dissociated.