High temperature (GC)2 and (GC)2/CI-MS of nucleosides: Analysis of purinyl nucleoside isomer composition

The analysis of low-volatile polar nucleosides by (GC)²/FID and (GC)²/CI-MS, employing HMDS-deactivated glass capillary columns and on-column injection, is described. The four linkage isomers of a specific nucleoside, formed in the synthetic procedure, are in each case sufficiently well separated in the chromatogram; GC/CI-MS allows for a differentiation of N-7 and N-9 linkage isomers.     

Strontium-mediated selective protonation of unsaturated linkage of aromatic hydrocarbons and these derivatives

The selective protonation of aromatic hydrocarbons with at least two or more aromatic rings and aromatic compounds bearing unsaturated linkages can be achieved by metallic strontium metal with ammonium chloride and iodine, or ammonium iodide in tetrahydrofuran. The reaction system is ammonia-free in room temperature and the reaction proceeds high selectivity in moderate to good yields.     

固相有机合成

综述了近年来固相有机合成中采用的连接分子和连接策略及固相合成在有机合成中的应用。     

Oxygen bridged nitroanilines for quadratic nonlinear optics

Several nitro aromatic compounds bridged by an oxygen atom have been synthesized and their linear and nonlinear optical properties have been investigated. In one of the compounds (1), a powder SHG efficiency of 6.2 times of urea was observed while its absorption lies in the UV region. The highest molecular hyperpolarizability β, measured was 230×10⁻³⁰ for a compound (8f) with increased conjugation. Thermal stability of these compounds has been checked using differential scanning calorimetry and the decomposition temperature (T_d) was found to be high and lying between 266-298 °C. These molecules have potential importance as thermally stable, visible-transparent second order NLO materials.     

用固体核磁共振研究Al/P>1的磷酸铝分子筛AlPO4-5

用固体高分辩核磁共振（ＮＭＲ）方法对一系列Ａｌ／Ｐ＞１的新型磷酸铝分子筛ＡｌＰＯ４－５中磷和铝的结构状态及联结方式进行了研究，＾２７Ａｌ和＾３１Ｐ ＮＭＲ都给出了在分子筛骨架中存在有Ａｌ－Ｏ－Ａｌ联结方式的实验证据，寓示着在该体系中Ｐ和Ａｌ的排布不再遵循Ｌｏｅｗｅｎｓｔｅｉｎ规则。     

一种新型光致发光自愈合水凝胶的合成

采用自由基聚合法制备了具有光致发光特性的自愈合水凝胶, 解决了光致发光配合物在水相荧光猝灭的问题. 通过分子设计, 利用共价键将油溶性的含Eu稀土配合物引进水凝胶体系中, 发现该配合物在水凝胶体系中稳定存在, 不扩散. 含Eu稀土配合物具有紫外光致发光的特性, 赋予该水凝胶良好的可识别性. 同时该水凝胶含有动态硼酸酯键, 其快速愈合的特性使该水凝胶在受损后能短时间内修复损伤, 为制备可发光水凝胶和可识别生物医用材料提供了新的思路.     

Glycosyl linkage characteristics and classifications of exo-polysaccharides of some regionally different strains of Lentinula edodes by amplified fragment length polymorphism assay and cluster analysis

We report here the first combined amplified fragment length polymorphism (AFLP) analysis of genomic DNA fingerprinting data and cluster analysis of the exo-polysaccharide glycosyl linkage data of 10 regionally different strains of Lentinula edodes to compare their genetic and structural similarities and differences. In addition, the monosaccharide compositions, molecular weights, glycosyl structural linkages were investigated for the exo-polysaccharides extracted from these different phylogenetic groups of regionally different L. edodes. All exo-polysaccharides had similar molecular weight distribution between 1 × 10⁴ and 3 × 10⁶ Da and the monosaccharide composition analysis revealed the presence of heterogeneous materials containing glucose, mannose, xylose, galactose, fucose, rhamnose and arabinose in different ratios. Among these monosaccharides, the glucose contents are the highest for all but one strain, indicating that glucose probably is the building block of the backbones of these exo-polysaccharides. The AFLP assay data helped to classify the 10 L. edodes strains into three distinct genetic groups. Gas chromatographic and mass spectrometric (GC-MS) data revealed five different glycosyl linkage types for these exo-polysaccharides. Most of the exo-polysaccharide backbone structures contain (1 → 4)-linked-d-glucopyranosyl and (1 → 6)-linked-d-glucopyranosyl moieties. Arabinose 1 → 4 linkages and mannose 1 → 2 linkages also exist in all strains. The only differences among these linkages are their monosaccharide compositions leading to different degree of backbone and branch formations. Cluster analyses of the GC-MS data of the exo-polysaccharides of the 10 strains resulted in 10 dendrograms. However, four of the 10 dendrograms were identical and were obtained using the average, Ward and weighted linkage type method of Manhattan distance and using the Ward method of Euclidean distance. The results of cluster analyses were not very much different from that of the AFLP assay and allowed the comparison of genetic and structural similarities and differences.     

Exploring possible reaction pathways for the o‐atom transfer reactions to unsaturated substrates catalyzed by a [Ni‐NO2] ↔ [Ni‐NO] redox couple using DFT methods

The (nitro)(N‐methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO₂)(S₂CNHMe)(PMe₃)] complex catalyses efficiently the O‐atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO₂)(S₂CNHMe)(PMe₃)] ↔ Ni(NO₂)(S₂CNHMe)(PMe₃) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five‐member metallacycle intermediate, via a [3 + 2] cyclo‐addition reaction of HC≡CH to the Ni‐N = O moiety of the Ni(NO₂)(S₂CNHMe)(PMe₃)] complex, followed by a β H‐atom migration toward the C_α carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( ‐NO₂)(S₂CNHMe)(PMe₃)] [Ni( ‐ONO)(S₂CNHMe)(PMe₃)] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc.     

Complete balancing of the shaking moment in spatial linkages by adding planar noncircular gears

Summary A balancing device is introduced, which can be applied for balancing spatial linkages which contain input links with revolving kinematic pairs. The method consists in adding noncircular gears, proposed earlier to balance planar linkages, for the balancing of the shaking moment of spatial linkages. Some new formulae to determine the parameters are furthermore proposed. As an illustrative example, the method is used to balance an RSS'R spatial linkage.     

多柔体系统动力学方程一种数值求解方法

本文提出用含有二阶自校正功能的增广法和半隐式Runge-Kutta法相结合求解多柔体系统动力学中的微分-代数型方程。并给出了计算实例和实验验证。