Selective mono,bis, and trisiminoformylation of 2,4,6-trialkyl-1,3,5-triazines - unusual enol acylenamine tautomerism of hydroxyalkenyl-1,3,5-triazines

2,4,6-Trialkyl-1,3,5-triazines 1 can selectively be mono, bis or trisiminoformylated by reaction with trismorpholinomethane 2 or chloromethylene iminium salts 3 (Vilsmeier reagents), with each alkyl substituent reacting with only one molecule of the electrophile. The resulting aminoalkenyltriazines 4, 5 and 6 are partially or fully hydrolysed to corresponding formylation products. The latter exist either in enol or in unusual acylenamine tautomeric structures 10, 12 , and 13 , depending on the number of enamine or enol units found in the molecule. Reaction of triazines 1 with chlorobenzylidene iminium salts 16 gives monoiminobenzoylation to enaminotriazines 17 .     

Organotitanium chemistry 12. Synthesis of some new chiral cyclopentadienyl titanium and zirconium complex. The crystal structure of (S-cyclo-C4H7OCH2Cp)2TiCl2

Summary New chiral cyclopentadienyl-titanium and-zirconium complexes Cp₂TiCl₂, CpCpTiCl₂ and Cp₂ZrCl₂ (Cp=⁵ -cyclopentadienyl and Cp=substituted cyclopentadienyl), have been synthesized. The (S,S)-3 complex, which forms red plate crystals, has been studied by x-ray analysis. It belongs to the monoclinic space groupC2, witha 23.963(3),b 6.6470(6),c 12.6618(9) Å, 103.089(7)°, V=1964.4(3) ų and Z=4. The structure was relined to an R factor of 0.048 for 868 observed reflections.     

N-甲基-苯并哒嗪TCNQ复合物的晶体堆积分析

本文对1-N-甲基-苯并哒嗪TCNQ复合物(1-N-M_(ci) TCNQ_2)和2-N-甲基-苯并哒嗪TCNQ复合物(2-N-M_(ci) TCNQ_2)的晶体中排列进行堆积分析, 采用OPEC程序计算它们的堆积能。1-N-M_(ci) TCNQ_2的堆积能为-70.194 kcal mol~(-1), 2-N-M_(ci) TCNQ_2的堆积能为-66.945 kcal mol~(-1)。结果表明, 在这两种TCNQ复合物中, 给体分子的各向尺寸的差异小, 则对TCNQ排列的影响小, 有利于TCNQ分子排列成一维的柱子。     

投影图在分子结构及晶体结构学习中的应用

介绍投影图在展示分子及晶体中的对称元素、点阵抽取及了解密堆积中空隙分布情况等方面的应用。     

固体表面结构和常用表面分析技术

对在结构化学基础课中增加表面结构知识的内容进行了探讨 ,提出将“表面原子排布和表面电子态”、“表面化学组成”和“表面分析技术”等作为固体表面结构和性质教学的基本内容 ,同时将“单层分散原理”这一科技新发现作为从理论研究到实际应用的例子吸纳到教材中。介绍了单层分散的实验现象、原理及有关应用。     

Selective Protein Immobilization via DNA Conjugation under Microfluidic Laminar Flow

The feasibility of controlled protein immobilization via DNA conjugation by utilizing laminar flow in a microfluidic device was demonstrated. The glass surface in a microchannel was treated by oligonucleotides. The laminar flow brought different protein-DNA conjugates parallel into the microchannel. DNA recognition allows proteins to be delivered to the desired location. The total internal reflection fluorescence was also applied to monitor the process. Both the specificity and sensitivity were high, and the immobilization and removal of the proteins were repeatable. It was shown that with parallel detection of specific and non-specific recognitions, the accuracy of bio-assay would be effectively enhanced. This strategy could improve the performing quality of biosensors in microfluidic devices.     

Systematic separation and determination of some neutron-activated nuclides and actinides in fallout samples

A method for systematic separation and determination of some neutron-activated nuclides and actinides is described. The method is designed to utilize stable isotopes and radioactive tracers as chemical yield monitors and to separate nuclides of interest from a single limited sample. Gravimetric, spectrophotometric, radiometric and X-ray fluorescence analysis were used for determination of chemical yields of the nuclides. Overall chemical yields generally ranged from 60–90%. Separated and purified nuclides were detected by -spectrometry or isotope dilution -spectrometry. The detection limit for neutron-activated nuclides is 10⁷ nuclides and the precision is better than 3% RSD.     

第四级铵氢氧化物Hofmann消除反应的构象分析及反应机理

本文用DPCILO, CNDO程序分别计算了一些第四级铵离子不同构象的能量及电荷密度, 探讨Hofmann消除反应的机理, 结果表明构象规则能较好地说明Hofmann消除反应的机理, 只是“直链型”烷基的消除反应应按顺式E_2机理进行。     

Osteogenesis of Osteoblast Seeded Polyurethane-Hydroxyapatite Scaffolds in Nude Mice

Summary: Biodegradable porous polyurethane (PU) scaffolds were used in a tissue engineering approach to create new bone. Two groups of elastomeric bioresorbable PU disks were seeded with osteoblasts and implanted into nude mice. One group had disks of pure PU while the other group had disks of PU- hydroxyapatite composite (PU-HA). After 5 weeks both groups showed radiographic and histologic evidence of significant bone formation. As the new bone formed it replaced the PU scaffolds. Although not statistically significant, there was a trend toward more bone formation in the PU-HA group. Bioresorbable PU shows promise for use in bone tissue engineering.