Synthesis and Structural Characterization of Alkali Metal Guanidinates

Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides, MN（SiMe3）2 （M=Li or Na） in hexane or THF produced the alkali metal guanidinates { （i-PrN）2C [N（SiMe3）2]Li }2 （1） and { （i-PrN）2C[N（SiMe3）2]Na（THF） } 2 （2） in nearly quantitative yields. Both complexes 1 and 2 were well characterized by elemental analysis, IR spectra, ^1H and ^13C NMR spectra, and X-ray diffraction. It was found that the guanidinates adopt different coordination modes in these complexes.     

Synthesis and Crystal Structure of 2-Dehydroabsetyl-5-ethylsulfanyl-1,2,3,4 tetrazole

Six novel tetrazoles were designed, synthesized and characterized by NMR and elemental analysis. 2-Dehydroabietyl-5-ethylsulfanyl-1,2,3,4-tetrazole (4b), C23H34N4S, was struc-turally determined by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group P212121 with a = 7.391(3), b = 12.580(3), c = 24.036(8) A, V= 2234.8(13) A3,Z = 4, Mr=398.60, Dc=1.185 g/cm3,u= 0.160 mm-1, F(000) = 864, the final R = 0.0499 and wR = 0.0638 for 1228 observed reflections with I > 2σ(I). There are four rings in the crystal structure, and C(14) adopts the R absolute configuration. In addition, disordered C(19), C(20), C(21), C(22) and C(23) exist in the crystal structure.     

火焰原子吸收光谱法测定佛手瓜中的微量元素

采用干法硝化法对佛手瓜硝化,用乙炔-空气火焰原子吸收法测定佛手瓜中Mg、Mn、Zn、Fe、Cu 5种微量元素及Pb、、Ni两种重金属元素含量.结果显示,佛手瓜微量元素含量丰富,该方法测定的加标回收率在95.0％-105.0％之间,该法操作简单、准确度高,可用于佛手瓜类蔬菜的检测.     

光子晶体垂直腔面发射激光器的电流分布研究

对氧化限制型外腔式光子晶体垂直腔面发射激光器注入到有源区的电流密度分布进行了分析研究.提出三维电流分布计算模型,研究了光子晶体结构对电流密度分布和器件串联电阻的影响.研究发现,光子晶体孔刻蚀深度越深,电流分布圆对称性越差,引起的串联电阻越大.不同光子晶体图案对电流分布的均匀性和圆对称性也有很大的影响.该模型对于研究、设计氧化限制型外腔式光子晶体垂直腔面发射激光器提供了一个有用的分析方法.     

locale范畴中的逆极限

给出locale范畴中逆极限结构的明确描述 .借助于引入的一种新的极限形式———集体拉回 ,详细讨论了逆极限的性质 ,特别地 ,不用选择公理证明了locale形式的Steenrod定理 ,并且证明了紧空间式locale的逆极限一般不是空间式的 .作为在拓扑空间范畴中的应用 ,改进了经典拓扑学中的Steenrod定理     

Induced Near-Infrared Emission and Controlled Photooxidation based on Sulfonated Crown Ether in Water

Regulation of physio-chemical properties and reaction activities via noncovalent methodology has become one of increasingly significant topics in supramolecular chemistry and showed inventive applications in miscellaneous fields. Herein, we demonstrate that sulfonated crown ether can form very stable host-guest complexes with a series of push-pull-type photosensitizers, eventually leading to the dramatic fluorescence enhancement in visible and near-infrared regions. Meanwhile, severe suppression in singlet oxygen (¹O₂) production is found, mainly due to the higher energy barriers between the excited single and triple states upon host-guest complexation. Moreover, such complexation-induced tuneable ¹O₂ generation systems has been utilized in adjusting the photochemical oxidation reactions of polycyclic aromatic hydrocarbons (anthracene) and sulfides ((methylthio)benzene) in water. This supramolecularly controlled photooxidation based on the selective molecular binding of crown ether with photosensitizers may provide a feasible and applicable strategy for monitoring and modulating many photocatalysis processes in aqueous phase.     

Simultaneous reduction of nitro- to amino-group in the palladium-catalyzed Suzuki cross-coupling reaction

An efficient method for palladium-catalyzed Suzuki cross-coupling reaction with simultaneous reduction of nitro- to amino-group has been developed. This method allows nitro-substituted aryl halides to readily react with arylboronic acids, to afford aryl substituted aniline in low to excellent yields. The reaction was catalyzed by Pd(OAc)₂ (3 mol %) at 150 °C under atmospheric pressure in the presence of K₂CO₃ (3 equiv) in DMF/H₂O (5/1).     

Enhancing the stability of kinesin motors for microscale transport applications

Biomolecular motors, such as kinesins, have great potential for micro-actuation and micro- or nanoscale active transport when integrated into microscale devices. However, the stability and limited shelf life of these motor proteins and their associated protein filaments is a barrier to their implementation. Here we demonstrate that freeze-drying or critical point-drying kinesins adsorbed to glass surfaces extends their lifetime from days to more than four months. Further, photoresist deposition and removal can be carried out on these motor-adsorbed surfaces without loss of motor function. The methods developed here are an important step towards realizing the integration of biological motors into practical devices, and these approaches can be extended to patterning and preserving other proteins immobilized on surfaces.     

Syntheses and Crystal Structures of Lanthanide Complexes of New 15-Membered Macrocyclic Ligands with Three Pendant Acetato Groups

Two new 15-memhored fimctionalized macrocycles, dioxo-polyazacydoalkanes with three pendant acetato groups, have been synthesized by the condensation reaction of DTPA dianhy-dride (DTPA = diethylenetrlamlnepentaacetic acid ) with 1,2-di-amlnopropane, ( 15-DTPA-1, 2-pn), or 1, 2-diaminocydohex-ane, (15-DTPA-1,2-cy). Their lanthanide complexes [ Ln ( 15-DTPA-1,2-pn)(H2O)]2[Ln= Eu (1), Gd (2)] and [Ln(15-DTPA-1,2-cy)(H2O)]2[Ln= Eu (3), Gd (4)] were also pre-pared. Single crystal X-ray diffraction analyses of complexes 2 and 4 show that they have dimeric structures in solid state;each metal ion is nine-coordinated in a distorted tricapped-trig-onal prism. In complex 4, the coexistence of two diastereoiso-meric molecules in the crystal lattice was observed.