Density functional theory (DFT) and ab initio investigations of the electronic and molecular structures of the monomer and the dimer of trimethylaluminium

The electronic and molecular structures of the monomer and dimer of trimethylalu-minium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C3h symmetry, whereas that of the dimer [A1(CH3)3]2 contains a carbon-bridged four-membered ring structure with C2h symmetry. The hydrogen-bridged six-membered ring structure is found to be unstable. The calculated dimerization energy for the four-membered ring structure is 78 kJ/mol, in close proximity to the experimental value of 85.27 kJ/mol.     

OXIDATION DECARBONYLATION OF NH_4[Mo(CO)_5I]: SYNTHE-SES AND CRYSTAL STRUCTURES OF CMo(S_2CNC_4H_8)_4]I_3 · C_7H_8 and Mo_2S_2O_2(S_2CNC4H_8)_2

<正> Both of the title complexes were produced by oxidative decarbony-lation of NH4 CMO (CO)5I]. The complexes CMo(S2CNC4H8)4]I3 ?C7H8(1) and Mo2S2O2 (S2CNC4H8)2(2) both crystallize in triclinic, space group P1 with cell dimensions for (1) : a=13. 554(4), b=13. 620(4), c= 13. 058 (4) A , α=95. 58 (3), β=105. 38(2), γ=115. 49(2)°,V = 2035(1) A3, Z=2, Dc=1. 89 g. cm-3, final R=0. 054 and Rw = 0. 062 for 2926 observed reflections; and for (2): a = 8.730(2), b=16.592(6), c = 6. 688(2)A, α=97. 67(3), β=98. 10(2), γ=80. 26(2)% V = 939. 2(5) A3, Z = 2, Dc = 2. 05 g. cm-3, final R = 0. 038 and Rw = 0. 046 for 2248 observed reflections. The Mo(V) atom is bonded to eight S atoms in distorted dodecahedron for (1). The Mo atoms in compound (2) are bridged by two S atoms and each Mo atom is coordinated by two S atoms from S2CNC4H8 and one O atom to form distorted tetragonal pyramid.     

λ-卡拉胶有限水解物在蛋白质置换层析分离中的应用研究

λ－卡拉胶经过有限酸水解得到不同平均分子量的组分，选用平均分子量为21kDa的组分，作为蛋白质置换层析的置换制，用于纤维素酶的分离纯化。经过置换层析，使黑色葡萄状穗霉S607发酵液中难以通过常规的分子筛和离子交换层析分离的一个内切酶组分（EGⅢ）和一个β－葡萄糖苷酶组分得到较好的分离。     

Synthesis of Gingerenone C and 5-Hydroxy-1-(4′-hydroxy-3-methoxyphenyl)-7-(4′′-hydroxyphenyl)-3-heptanone

Diarylheptanoidsconstituteadistinctgroupofmetabolitesofnaturalplantcharacterizedbytwoaromaticringslinkedbyalinearsevenaliphaticchain.Therehavebeenfewreportsonthebiologicalactivitiesofdiarylheptanoids,mostofwhichappearingintheareasofanti-inflammatory,anti-oxidative,superoxidescavengingandanti-hepatotoxiceffects1,2.SomeofthemareusedastraditionalmedicineinAsia3.Compound1and2werefirstlyisolatedfromtherhizomesofZingiberofficalrespectively4,5.Sofarthesynthesisofthesetwocompoundshavenotbeenreportedy…     

A Green and Facile Solid-state Synthesis Method for the Preparation of Diazenecarboxamide Azo Compounds with Potassium Ferricyanide and Sodium Hydroxide System

Eleven new-typed azo compounds were synthesized in good yields by dehydrogenating the corresponding aryl substituted semicarbazides using potassium ferricyanide and sodium hydroxide system under solid-state conditions.     

苯醚甲环唑在芹菜及其土壤中的残留测定和消解动态研究

采用气相色谱-电子捕获检测, 对芹菜及其土壤中的苯醚甲环唑消解动态和最终残留量进行了研究, 评价了苯醚甲环唑在芹菜上使用后的残留行为和环境安全性. 苯醚甲环唑在芹菜及土壤中的残留消解动态均符合一级动力学方程, 苯醚甲环唑在芹菜上消解快; 苯醚甲环唑最终残留量与施药的剂量、施药次数及采样的间隔时间有关; 水解研究表明, 苯醚甲环唑是稳定的农药, 在不同温度和不同pH的研究条件下水解半衰期均大于166 d, 碱性条件更有利于苯醚甲环唑的降解.     

New Diterpenoid Alkaloids from Spiraea japonica var. Ovalifolia

In the investigation of the chemical constituents of Spireae japonica L. f. var. ovalifolia (Rosaceae), a shrub originated in Songming, Yunnan, five new diterpenoid alkaloids, 19-O-deethylspiramine N (1), deacetylspiramine S (2), spiramidine A (3), spiramidine B (4) and deacetylspiramine F (5), were isolated from aerial parts of the plant and structurally elucidated. Compound 1, a white amorphous powder with [(]+17.99 (c, 0.26, MeOH ), was determined to have the molecular formula of C20H…     

Exploring modular domino reactions: competing processes based on the nature of the angular substituent

The octaline diol system 6 was found to undergo an interesting set of reactions upon treatment with PhI(OAc)2, leading, in a single synthetic operation, to complex oxygen heterocycles. Experimental evidence supports an intramolecular hetero[4 + 2 + 2] adduct that has heretofore never been observed, which completely dominates the hetero[4 + 2] path in several cases. The domino protocol can be biased one way or another depending on both the nature of the pi-system and the length of the methylene spacer at the angular position.     

制备方法对聚合物共混物相分离与黏弹弛豫的影响

采用小角激光光散射(SALLS)和动态流变方法研究了通过不同制备方法得到的等规聚丙烯/乙丙橡胶共混物(iPP/EPR)的相分离行为与黏弹行为.依据Cahn-Hilliard-Cook理论分析了熔融共混和溶液共混法制备的质量比为60/40和40/60的iPP/EPR共混物在恒温相分离早期的动力学,发现熔融共混iPP/EPR具有更大的表观扩散系数(Dapp).相分离中后期的实验结果表明,当相区尺寸增长程度相同时,熔融共混试样所用时间更短.表明熔融共混iPP/EPR试样具有更快的相分离速率.动态流变测试结果表明,与溶液共混相比,熔融共混试样具有更快的松弛速率.考虑到相分离过程实质是由高分子链的运动与扩散所控制,两种方法制备的iPP/EPR共混物相分离速率的差异应归于其分子链运动能力的不同.     

Synthesis,Structure and Photoluminescence of Two Zinc Carboxylate Polymers with Different Coordination Architectures

Introduction　　Thesynthesisofmetal organicpolymershasundoubt edlybeenatopicofspecialinterestduetotheirhost guestinteractionswhichhavebeentailoredtoavarietyofindus trialprocessessuchascatalysis ,adsorptionandgassepa ration .1 5Sofar ,manyeffortshavebeendedicatedtotheexplorationofmetal organicframeworkmaterialsbuiltupfrommetallicclustersandrigidorganicbuildingblocks .Thisstrategy ,asreportedbythegroupsofRobson ,6Yaghi7 11andothers ,utilizesrigidorganiclinkersfordi rectlylinkingthemetalclusters…