枝状聚硅烷光学及其稳定性

聚硅烷;光学性能;光热稳定性;热降解动力学     

邻氯苯甲腈的新合成法

以邻氯溴苯为起始原料,选用K4[Fe(CN)6]为氰基化试剂,Pd/C催化反应制得邻氯苯甲腈。 考察了温度、碱、催化剂的用量和原料比等对反应的影响,确定了较佳反应条件。 邻氯溴苯转化率达98.5%,产物邻氯苯甲腈得率95.1%。     

磷酸特地唑胺的合成新方法

以(5R)-3-(4-溴-3-氟苯基)-5-羟甲基噁唑烷-2-酮为起始原料,在[PdCl₂(dppf)]·CH₂Cl₂催化下与联硼酸频那醇酯反应得到硼化物,继而与5-溴-2-(2-甲基-2H-四唑-5-基)吡啶进行Suzuki反应得到特地唑胺,收率82.9%。 分别考察了催化体系对硼化反应和Suzuki反应的影响,确定了较佳的反应条件。 特地唑胺与二苄基N,N-二异丙基亚磷酰胺反应得到二苄基保护的磷酸特地唑胺,随后经Pd/C脱苄得到磷酸特地唑胺,总收率66.2%。     

Telluride-Based Materials: A Promising Route for High Performance Supercapacitors

As supercapacitor (SC) technology continues to evolve, there is a growing need for electrode materials with high energy/power densities and cycling stability. However, research and development of electrode materials with such characteristics is essential for commercialization the SC. To meet this demand, the development of superior electrode materials has become an increasingly critical step. The electrochemical performance of SCs is greatly influenced by various factors such as the reaction mechanism, crystal structure, and kinetics of electron/ion transfer in the electrodes, which have been challenging to address using previously investigated electrode materials like carbon and metal oxides/sulfides. Recently, tellurium and telluride-based materials have garnered increasing interest in energy storage technology owing to their high electronic conductivity, favorable crystal structure, and excellent volumetric capacity. This review provides a comprehensive understanding of the fundamental properties and energy storage performance of tellurium- and Te-based materials by introducing their physicochemical properties. First, we elaborate on the significance of tellurides. Next, the charge storage mechanism of functional telluride materials and important synthesis strategies are summarized. Then, research advancements in metal and carbon-based telluride materials, as well as the effectiveness of tellurides for SCs, were analyzed by emphasizing their essential properties and extensive advantages. Finally, the remaining challenges and prospects for improving the telluride-based supercapacitive performance are outlined.     

高性能聚苯并(噁)嗪树脂

聚苯并噁嗪树脂作为一种新型酚醛树脂,不仅具有优异的耐热性和阻燃性,而且克服了传统酚醛树脂在成形固化过程中释放小分子的缺点,在制备高性能材料方面已引起研究者的广泛关注。本文综述了近年来国内外为制备高性能化聚苯并噁嗪树脂所作的一些研究工作,包括从主链或侧链中引入苯环等刚性官能团、在主链或侧链中引入可聚合官能团、与另一种高分子形成共混或共聚物以及与其他材料复合形成复合材料等,并对该树脂材料的工业开发前景、国内外研究现状以及发展趋势进行了分析。     

Benzocyclobutenes: A New Class of High Performance Polymers

Benzocyclobutenes are a family of thermally polymerizable monomers which can be classified into two groups: 1) monomers which contain only benzocyclobutene moieties and 2) monomers which contain sites of unsaturation in addition to benzocyclobutene moieties. The monomers can be partially polymerized (B-staged) by heating to form oligomers having processing advantages for various composite fabrication techniques. The polymerization proceeds through the thermally initiated cyclobutene ring opening to yield an o-quinodimethane intermediate (calculated to be a ground state singlet). Preliminary characterization of the network structures indicates that monomers which contained multiple benzocyclobutene moieties, optionally with sites of unsaturation, were transformed into multifunctional network junctions when the thermosets were fully cured. The 3-maleimidobenzocyclobutenes thermally polymerize to yield substantially linear, high glass transition temperature (T_g) polymers. Thus benzocyclobutene polymers encompass materials which have properties ranging from high T_g, thermosets to those of substantially linear thermoplastics. Some polymers exhibit an excellent retention of their room temperature mechanical properties to at least 200-250°C, making them useful as high performance polymers for applications in the aerospace industry. Other polymers have outstanding electrical properties including very low dielectric constant and water pickup, making them useful in electronic applications.     

A New Bonded-Phase for High Performance Liquid Chromatographic Analysis

Abstract

A silica bonded-phase with carboxylic acid functionality and a side chain of three carbon atoms has been synthesized for HPLC analysis. Mixtures of nucleic acid bases, PTH-amino acids, phospholipids and ethanolic extract of dry ginger powder were analyzed to demonstrate its performance. Nucleic acid bases and PTH-amino acids were separated by cation-exchange mechanism whereas phospholipids experienced combination of cation-exchange and normal-phase resolution. The resolution of gingerols in the dry ginger powder was achieved by reversed-phase mechanism.     

A Synthetic Route Toward Tetrazoles: The Thermolysis of Geminal Diazides

A new synthetic route toward the tetrazole core is described, which is based on a general fragmentation pattern that was found in a range of compounds featuring geminal diazido units. Through a simple two-step procedure, the synthesis of structurally diverse target compounds containing a tetrazole, such as tetrazoloquinoxalinones, benzoylaryltetrazoles, tetrazolotriazinones, and tetrazoloazepinones, was easily accomplished, starting from broadly accessible substrates (i.e., oxindoles, diarylethanones, pyrazolones, and phenanthrols). The initial oxidative diazidation reaction with iodine and sodium azide under mild conditions is followed by the thermal fragmentation under microwave irradiation, leading to the tetrazole products. Noteworthy, an experimental solution is presented in which the potentially hazardous diazide intermediates are not isolated and the concentration of crude reaction mixtures containing diazides is not required to achieve the tetrazoles in good yields.     

A New Route to 3-Phosphonylpyrazoles

The regioselective synthesis of 3-diethoxyphosphonopyrazoles has been accomplished through the addition of aryl or alkyl hydrazines to (3-ethoxyacryloyl)phosphonic acid diethyl ester. An example of hydrolysis of the pyrazolephosphonic ester to the corresponding acid is described.     

A New Route to Metal Azides

Beside several other applications, metal azides can be used for the synthesis of nitridophosphates and binary nitrides. Herein we present a novel synthetic access to azides: Several metals, such as main‐group, transition metals, and rare‐earth metals, react with silver azide in liquid ammonia as a solvent giving the corresponding metal azides. In this work Mn(N₃)₂, Sn(N₃)₂, and Eu(N₃)₂, as well as their ammonia complexes were synthesized for the first time through low‐temperature methods. Also a simpler access to Zn(N₃)₂ was possible. At room temperature and the respective vapor pressure of NH₃, it became possible to grow single crystals of the dinuclear holmium azide [Ho₂(μ‐NH₂)₃(NH₃)₁₀](N₃)₃?1.25 NH₃. We are confident that this new route could lead to novel metal azides as well as nitrides of the main‐group, the transition, and the rare‐earth metals upon careful decomposition.     

A New Route to Heterosilsesquioxane Frameworks

The substitution of an O atom in the Cy₈Si₈O₁₂ framework by a heteroatom or a heteroatom-containing group (Z) provides a simple route to discrete heterosilsesquioxane frameworks 1 . In this reaction the Cy₈Si₈O₁₂ framework is initially opened with triflic acid and then treated with different nucleophiles (Cy=cyclohexyl; Z=NPh, SO₄, nBuBO₂, CrO₄).     

New Soluble Near‐Infrared Dyes Based on Terrylene Diimides with Four Aromatic Heterocycles

Terrylene diimides with four aromatic heterocycles (AHTDIs) were synthesized under Stille Cross‐coupling conditions and fully characterized by NMR and mass spectrometry. The aggregation of the terrylene diimide (TDI) was suppressed by four heterocycles substituents on the bay region, and these AHTDIs exhibited good solubility in common organic solvents. The effects of the substituted groups on the optical and electrochemical properties were also investigated. The introduction of four aromatic heterocycles on the bay of TDI resulted in significant red‐shifts of the absorption peak (100 nm), corresponding to a decrease in the band gap from 1.82 to 1.50 eV. Furthermore, with four rich electron aromatic heterocycles, the AHTDIs showed 280 mV negative‐shifts of first oxidation potentials and a new oxidation wave, corresponding to an increase in the HOMO levels from??5.60 to??5.28 eV.     

新型孪尾Gemini两性离子表面活性剂应用性能

分别采用改进的Ross-Miles法及分水时间法,对3种新型孪尾Gemini两性离子表面活性剂(C8C8L3Sz、C8C8L4Sz和C10C8L3Sz)的泡沫性能及乳化性能进行了研究,并考察了表面活性剂浓度、分子结构和温度等对其的影响。 结果表明,该系列表面活性剂具有较好的泡沫性能,且随其浓度的增加,泡沫最大高度和半衰期均存在一个稳定值,疏水链越长,其起泡性能越差,泡沫稳定性越好;温度升高,起泡性能变好,泡沫稳定性变差;当表面活性剂浓度一定时,体系中加入低浓度的短链醇及无机盐均能提高泡沫的稳定性;C8C8L3Sz、C8C8L4Sz和C10C8L3Sz作乳化剂的最适宜的用量分别为6×10-4、6×10-4和4×10-4 mol/L,疏水基越长,乳化性能越好,而连接基对其影响较小;温度升高,乳化性能变差;当油相烷烃碳数相同时,环烷烃要比直连烷烃更易达到最佳乳化效果,但二者的乳状液稳定时间相当;对于油相烷烃碳数不同时,烷烃的碳链越长,乳状液的稳定性越差,乳化效果越不好。     

A New Route for Synthesis of Entecavir

2-Amino-1,9-dihydro-9-[(1S,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopen tyl]-6H-purin-6-one (entecavir, Scheme 1) is a novel carbocyclic 2-deoxyguanosine analog drug which has potent and selective anti hepatitis B virus (HBV) activity1-3. Entecavir is also effective against lamivudine-resistant YMDD mutants4. The US Food and Drug Administration (FDA) approved entecavir as a new preferred drug for the treatment of HBV after lamivudine in March, 2005. Scheme 1 The structure o…     

A New Spherical Hydroxyapatite for High Performance Liquid Chromatography of Proteins

Abstract

Basic properties of a newly developed hydroxyapatite column and results of its application to the separation of proteins are described. The hydroxyapatite was completely spherical and porous beads in appearance by scanning electron microscopy, and showed superior properties to other types of hydroxyapatite column. The column was mechanically strong enough to show the pressure limit of 140–150 kg/cm². The hydroxyapatite column showed excellent mechanical and chemical stability, and was applicable to high speed and high resolution separation of proteins. Proteins are recovered in high yield after the chromatography.     

Zirconium Promoted Ring Opening. A New Route to Phosphinites and Polyphosphinites

Abstract

Ring opening reactions involving various heterocycles, the Schwartz reagent [Cp₂ZrHC1]_n and a number of chlorophosphines or phosphenium salts will be presented. Scope and limitations of this useful methodology will be discussed.