葡萄糖B-Z体系中酸度变化诱导的复杂振荡反应

本文首次报导了葡萄糖-KBrO₃-丙酮-MnSO₄-H₂SO₄体系的化学振荡反应,在这一体系中改变酸度可产生一系列复杂的振荡现象,当[H₂SO₄]₀>0.36mol·l^-1或[H₂SO₄]₀<0.074mol·l^-1时,体系分别出现二种不同类型的振荡波形OA和OB,OA振荡存在一诱导期,OB振荡无锈导期;OA的振幅较小,但振荡频率比OB快得多;OB的振荡周期逐渐缩短,但OA.却相反变化.当0.074mol·l^-1<[H₂SO₄]₀<0.36mol·l^-1时,体系同时出现上述二种类型的振荡波形,中间存在一过渡区域,即产生连续振荡波形.文章讨论了诱导期及过渡时间与[H₂SO₄]₀的关系,对酸度的影响机理作了说明.     

Cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic and benzylic Grignard reagents and their application to tandem radical cyclization/cross-coupling reactions

Details of cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic Grignard reagents are disclosed. A combination of cobalt(II) chloride and 1,2-bis(diphenylphosphino)ethane (DPPE) or 1,3-bis(diphenylphosphino)propane (DPPP) is suitable as a precatalyst and allows secondary and tertiary alkyl halides--as well as primary ones--to be employed as coupling partners for allyl Grignard reagents. The reaction offers a facile synthesis of quaternary carbon centers, which has practically never been possible with palladium, nickel, and copper catalysts. Benzyl, methallyl, and crotyl Grignard reagents can all couple with alkyl halides. The benzylation definitely requires DPPE or DPPP as a ligand. The reaction mechanism should include the generation of an alkyl radical from the parent alkyl halide. The mechanism can be interpreted in terms of a tandem radical cyclization/cross-coupling reaction. In addition, serendipitous tandem radical cyclization/cyclopropanation/carbonyl allylation of 5-alkoxy-6-halo-4-oxa-1-hexene derivatives is also described. The intermediacy of a carbon-centered radical results in the loss of the original stereochemistry of the parent alkyl halides, creating the potential for asymmetric cross-coupling of racemic alkyl halides.     

Measurement of the sign and the magnitude of heteronuclear coupling constants from spin-state-edited J-cross-polarization NMR experiments

New spin-state-selective (S3) NMR pulse sequences exclusively applying cross-polarization schemes to achieve optimum homonuclear and heteronuclear 1H-X coherence transfer are reported for the simple and accurate measurement of the magnitude and sign of heteronuclear coupling constants for samples at natural abundance. The proposed spin-edited HCP-TOCSY experiments are based on clean heteronuclear S3 excitation, generated by simultaneous co-addition of two independent in-phase and anti-phase components created during the mixing heteronuclear J-cross-polarization (HCP) step, which is finally transferred to other protons by a conventional homonuclear TOCSY mechanism. Selective 1D and non-selective 2D approaches for the easy determination of long-range proton-carbon and proton-nitrogen coupling constants on any protonated and non-protonated heteronuclei are presented and discussed for several organic molecules.     

Stille Cross‐Coupling of a Racemic Planar‐Chiral Ferrocene and Crystallographic Trace Analysis of Catalysis Intermediates and By‐products

A pressure‐controlled procedure for the S_N1 reaction of rac‐1‐[(dimethylamino)methyl]‐2‐(tributylstannyl)ferrocene ( 1 ) to rac‐1‐(phthalimidomethyl)‐2‐(tributylstannyl)ferrocene ( 2 ) was developed. Pd⁰‐Catalyzed Stille coupling of 2 with iodobenzene afforded rac‐1‐phenyl‐2‐(N‐phthalimidomethyl)ferrocene ( 5 ) in 74% yield; after trace enrichment by crystallization of the combined mother liquors, one single crystal of each, 5 , catalysis intermediate trans‐iodo(σ‐phenyl)bis(triphenylarsino)palladium(II) ( 7 ), trans‐diiodobis(triphenylarsino)palladium(II) ( 8 ), and rac‐2,2′‐bis(phthalimidomethyl)‐1,1′‐biferrocene ( 9 ) could be isolated by crystal sorting under a microscope and characterized by X‐ray crystal structure analysis. Furthermore, 5 was deprotected to amine ( 11 ), which does even survive the Birch reduction to rac‐1‐(aminomethyl)‐2‐(cyclohexa‐2,5‐dienyl)ferrocene ( 12 ).     

Si4+Si3反应动力学：振动激发态对反应的影响

用准经典轨线方法研究了处于振动激发态的硅原子团簇与硅原子团簇碰撞的反应动力学，计算表明，对于Ｓｉ４＋Ｓｉ３反应，当反应物团簇处于振动激发态时，有利于生成更小团簇的碎片，而对生成Ｓｉ６＋Ｓｉ及Ｓｉ５＋Ｓｉ２的影响不大。     

How can the Cross-Link Adducts Formed by Novel Trans Platinum Drug be Influenced by Hydrogen Bond

A systematic quantum chemical characterization of intrinsic structure, energies and spectral properties of all the studied cross-link adducts formed by the novel trans platinum with thiazole ligand has been carried out at B3LYP/6-31G^＊ level of theory with the Lanl2dz pseudo potential basis set for the Pt atom. Special attention has been paid to the relative stability of these complexes and the factors that probably alter the order of the relative stability. The important influence of hydrogen bond on the structures, the energies and the spectral property was revealed. Other factors that contribute to relative stability including solvation effect, entropy and electronic delocalization energy were taken into account. The stability energy of the whole complex, and the interaction energy between two purine bases and the [Pt-（NH3）thiazole]^2＋ group were adopted to study the interplay among subsystems and their contribution to relative stability of all the studied cross-link model. Finally, basic spectral properties of these complexes including H（8） chemical shifts of all the studied complexes and the VCD （vibrational circular dichroism） spectra of two pairs of GG chelate enantiomers, were provided in order to define the structure of the most possible duplex bearing novel trans platinum drug lesions.     

CROSS-LINKING OF AROMATIC POLY（THIOETHER）S

A novel cross-linking process using two high molecular weight aromatic poly(thioether)s,which were synthesized by the reactions of 4,4′-thiobisbenzenethiol with 4,4′-difluorobenzophenone and 4,4′-difluorodiphenylsulfone,respectively, and commercially available lower molecular weight poly(p-phenylene sulfide)was investigated.These reactions were carried out in bulk by the addition of silver tetrafluroborate andα,α′-dibromo-p-xylene at 190℃over a period of 45 min. Furthermore,the same procedure could be modified to cross-link compression-molded films of these three polymers.The thermal and solubility behaviors of these polymers before and after cross-linking reactions,are presented.     

纳米ZnO的阳极消耗法制备和表征

采用阳极消耗法制备了纳米ZnO粉体,并利用XRD,TEM,XPS,UV-V is和PL测试技术对样品进行了表征.结果表明,所制样品为纤锌矿结构的纳米ZnO,颗粒呈类球形,平均粒径15 nm,具有很强的紫外吸收能力.位于531.44 eV的O1 s峰和PL谱上的绿带共同证明了氧空位存在,纳米ZnO的绿光发射带来自氧空位电子与价带空穴的辐射复合.     

液晶光定向层材料

本文综述了近10年来液晶显示用光定向层材料领域的研究现状和进展情况，主要概述了光降解型、光致异构型、光交联型以及自组装等材料，并对目前报道的液晶光定向机理进行了总结和归纳。     

活性酯固化邻甲酚环氧树脂反应机理的研究

采用交叉反应研究在促进剂2-甲基咪唑存在下活性酯固化邻甲酚环氧树脂的反 应机理，用傅立叶转换红外（FTIR）原位测量技术，NMR，气-质联用（GC-MS）等 手段研究了模型化合物的反应动力学，并提出了其反应机理。结果表明，在促进剂 2-甲基咪唑存在下活性酯固化邻甲酚环氧树脂的反应是通过分子内机理进行的。