<Emphasis Type="Italic">Ab initio</Emphasis> study of small coinage metal telluride clusters Au<Subscript>n</Subscript>Te<Subscript>m</Subscript> (<Emphasis Type="Italic">n,m</Emphasis> = 1, 2)

The geometries of the most stable isomers of gold telluride systems AuTe, Au₂Te, and AuTe₂ are determined using the MP2 method. The aspect of gold—telluride interaction, the electron correlation, and relativistic effects on geometry and stability are investigated at the MP2 and CCSD(T) theoretical levels. The results show that the electron correlation and relativistic effects are responsible not only for gold—gold attraction but also for additional gold—telluride interaction. The gold—telluride interaction is strong enough to modify the known pattern of bare gold clusters. Both effects are essential for determining the geometry and relative stability of this type of systems.     

Influence of post-annealing temperature on properties of ZnO:Li thin films

Li-doped ZnO thin films were prepared on glass substrates by DC reactive magnetron sputtering. The influence of post-annealing temperature on the electrical, structural, and optical properties of the films was investigated. A conversion from p-type conduction to n-type in a range of temperature was confirmed by Hall measurement. The optimal p-type conduction is achieved at the annealing temperature of 500 °C with a resistivity of 57 Ω cm, carrier concentration of 1.07 × 10¹⁷ cm⁻³ and Hall mobility of 1.03 cm² V⁻¹ s⁻¹. From the temperature-dependent PL analysis, the energy level of Li_Zn acceptor was determined to be 140 meV above the valence band.     

Study on oxidation of polymers treated by high LET radiation

The oxidation of medical silicone rubber and segmented polyether urethane which were bombarded with 11.2 MeV Si⁺ or F⁺ at the dose of 5 × 10¹⁴ ions/cm² was studied. In XPS measurements, it was found that the oxygen concentration on the surface of the implanted polymeric membranes had been increasing in three months at least. ESR measurement showed that some free radicals existed in these membranes and their quantities decreased with time. Chemical analysis proved that peroxides were generated in the γ irradiated membranes. The reason for the increasing of oxygen concentration was that free radicals combined with oxygen in the air and produced peroxides on the membrane surface. Moreover, in order to demonstrate the radiation mechanism, low LET (γ rays) radiation of such polymeric membranes was carried out for comparison     

Determination of lutetium by fluorimetry, using BPMPHD and CTMAB

Lutetium(III) forms an association compound with a new synthetic reagent, 1,6-bi(1-phenyl-3-methyl-5-pyrazolone-4)hexandione (BPMPHD), and cetyltrimethylammonium bromide (CTMAB). The compound enhances the natural fluorescence of BPMPHD remarkably, upon which a new fluorescence method was developed for determining lutetium in rare earth (RE) samples. The determination range was 1.80 × 10^–7–8.8 × 10^–6 g/ml. The determination limit was 29 ng/ml. The composition of the ion associate was [Lu(BPMPHD)₂]–CTMAB⁺.     

Synthesis and Insulin—sensitizing Activity of a Series of 2—Benzyl—1,3—dicarbonyl Derivatives

A series of 2-benzyl-1,3-dicabonyl derivatives was synthesized.Their insulin-sensitizing activity was evaluated in 3T3-L1 preadipocyte cells.Compounds3,26 and 27 were found to possess strong insulin-sensitizing activity in vitro and were selected for further hypoglycemic evaluation in vivo.     

钴膦簇合物的催化环丙烷化反应

本文首次利用碳基钴簇合物ＰｈＰＣｏ_３（ＣＯ）_９催化剂，在常压和－２０℃－０℃，用苯乙烯和重氮乙酸乙酯进行环丙烷化反应，合成了菊酸酯，重氮乙酸乙酯可全部转化，酯的选择性可达８５％。产物经减压分馏后，由ＩＲ和￣１ＨＮＭＲ分析，确证了产物为菊酸酯，表明了羰基钴簇合物对苯乙烯的环丙烷化反应有良好的催化性能，为四面体异核簇合物用于不对称催化反应打下了基础。     

尼龙1010／尼龙6共聚物的表观相图研究

采用显微熔点法和ＤＳＣ测定了尼龙１０１０／尼龙６共聚物的表观相图；分析了投料比与链节结构单元含量的关系。最低熔点时尼龙１０１０／尼龙６的理论重量投料比为６０／４０，摩尔比为３３．３／６６．７，实验结果与此相近。     

Direct Trimethylsilylation of Phenanthrene and its Products—An Abnormal Silylation of Phenanthrene

Direct trimethylsilylation¹⁾ of phenanthrene in different molar ratio of phenanthrene/sodium/trimethylchlorosilane is reported and discussed. Instead of the aromatic silyl compounds, such as 9-trimethylsilylphenanthrene (V), the hydroaromatic silyl compounds, such as 9, 10–bis (trimethylsilyl)-9, 10-dihydrophenanthrene (I) were obtained preferentially. Structure of these compounds are characterized and discussed. These silylated products have a general trend to change their properties during long time storage in the atmosphere under exposure to light. A significant difference of chemical shifts between silylated aromatic compound (V) and silylated hydroaromatic compound (I-IV) was observed.     

Novel metathesis catalysts based on ruthenium 1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidenes: synthesis, structure, immobilization, and catalytic activity

The synthesis of novel ruthenium-based metathesis catalysts containing the saturated 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene ligand, that is, [RuCl2(NHC)[=CH-2-(2-PrO)-5-NO(2)-C6H3]] (1) and [Ru(CF3COO)2(NHC)[=CH-2-(2-PrO)-5-NO2-C6H3]] (2) (NHC=1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) is described. Both catalysts are highly active in ring-closing metathesis (RCM) and ring-opening cross-metathesis (ROCM). Compound 1 shows moderate activity in enyne metathesis. Compound 2 is not applicable to enyne metathesis since it shows high activity in the cyclopolymerization of diethyl dipropargylmalonate (DEDPM). Poly(DEDPM) prepared by the action of 2 consists of 95% five-membered rings, that is, poly(cyclopent-1-enevinylene)s, and 5 % of six-membered rings, that is, poly(cyclohex-1-ene-3-methylidene)s. The polymerization proceeds in a nonliving manner and results in polyenes with broad polydispersities (1.9< or =PDI< or =2.3). Supported analogues of 2 were prepared by immobilization on hydroxymethyl-Merrifield resin and a monolithic support derived from ring-opening-metathesis polymerization (ROMP). Catalyst loadings of 1 and 2.5%, respectively, were obtained. Both supported versions of 2 showed excellent reactivity. With 0.24-2% of the supported catalysts, yields in RCM and ROCM were in the range of 76-100%. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014% (0.14 ppm).