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991.
Synthesis and Structural Characterization of [Mn(sapn)(H2O)2]Br 总被引:1,自引:0,他引:1
1 INTRODUCTION Many of the recent advances in the coordination chemistry of manganese have been driven by the involvement of the manganese in several biological redox-active systems[1,2], of which the most important is the oxygen-evolving complex (EOC) of photosystem II (PS II) in green plants [3]. Since the preparations and structural characterizations of the complexes containing N,O-donor ligands have been studied extensively as simple active-site models for the photosystem II[4,5]… 相似文献
992.
Lophenol, cholest-4α-methyl-7-en-3β-ol (1), obtained from Dracaena cochinchinensis (Lour.) S. C. Chen, was structurally modified. It was acetylated to protect 3β-hydroxyl group, and then oxidised by selenium dioxide in acetic acid to give cholest-4a-methyl-8-en-3β, Ta-diol diacetate (3). This compound 3 is unstable in chloroform solution or when heated and easily converted to a diene compound, cholest-4a-methyl-7,14-dien-3β-ol acetate (4). The structures of 3 and 4 were elucidated by means of IR, ^1H NMR, ^13C NMR and MS, and the absolute configuration of 3 was established by X-ray crystallography. The property of 3 was also discussed in this paper. Both 3 and 4 are new compounds and were reported for the first time. 相似文献
993.
Two novel supramolecular complexes [Cu(bpapa)(dhbd)]·CHaOH (1) and [Cu(bpapa)(ma)]·ma (2) (bpapa= bis[6-(2-pyridylamino)pyrid-2-yl]amine, dhbd=2,3-dihydroxybutanedioate dianion, ma=a-methacrylate) were rationally designed, synthesized and characterized by single crystal X-ray diffraction, IR, electronic spectroscopy and thermogravimetric analyses. Complex 1 was the first oligo-a-pyfidylamino complex based on hydroxypolycarboxylate and self-assembled into a 3D honeycomb configuration network with open channels and tubes containing 1D ladder-shaped double chains formed by hydrogen bonds and aromatic π-π stacking interactions. Complex 2 constructed a 2D supramolecular network extended by 1D chains from dimeric supramolecular synthon through noncovalent supramolecular interactions. In the two complexes, the chelating monohelical ligand adopted all-anti configuration. Density functional theory calculations were applied to 1 and 2. 相似文献
994.
2,2’-二氨基苯氧基二硫化物的电极过程动力学研究 总被引:1,自引:0,他引:1
利用循环伏安法、线性伏安法及旋转圆盘电极技术,研究了2,2’-二氨基苯氧基二硫化物(DAPOD)在含有0.1 mol•L-1 LiClO4电解质的乙腈/四氢呋喃有机溶液中,铂、金、玻碳及石墨电极上的电化学行为.伏安结果表明DAPOD中的二硫键与硫巯基之间的氧化还原反应属动力学不可逆过程,这种在室温下表现出的电化学反应不可逆性是有机二硫化物普遍存在的不足,必须通过分子内或分子间的电催化来改善其可逆性能.旋转圆盘电极测试结果显示, DAPOD的阴极还原反应级数为0.5,阳极氧化反应级数为1.由此推知DAPOD电还原属两电子转移反应,分两步完成:第一步为平衡的化学反应步骤;第二步为电子转移步骤,属决速步.同时还测定了DAPOD的阴极与阳极传递系数、交换电流、平衡电势及标准速率常数等相关的动力学常数.通过比较铂、金、玻碳及石墨四种不同材料电极对DAPOD的电极过程的影响,发现石墨对DAPOD的还原过程具有电催化作用. 相似文献
995.
A highly-efficient preparative procedure for ( R, S )- and ( S, S)-pyrroHdine-2-carboxyHc acid 3,5-dioxa-4-boracyclohepta[2, 1-α ; 3,4-α′] dlnaphthalen-4-yl esters [ namely ( R, S )-BNBAP and (S, S )-BNBAP] is described and the crystal structure of (R, S )-BNBAP was obtained. The data indicate that ( R, S )-BNBAP is a spirocyclic inner borate salt with almost normal te-trahedral configuration. This structural form may be the basic reason for their high chemical, optical and thermodynamic sta-bility. 相似文献
996.
(E)-α-Aryltellurenylvinylstannanes have been synthesized stereoselectively via the hydrozirconation of alkynylstannanes, followed by the reactions with aryltellurenyl iodides. (E)-α-Aryltellurenylvinylstannanes can undergo sequential cross coupling reactions with both electrophiles and nucleophiles in the presence of transition metal complexes to form two carbon-carbon bonds in the same olefinic carbon leading to trisubstituted alkenes stereoselectively. 相似文献
997.
合成甲醇的催化剂Rh-ZnO/MWNTs的研究 总被引:2,自引:0,他引:2
研究新型的由多壁碳纳米管(MWNTs)负载的, ZnO助催的铑基甲醇合成催化剂. 当铑含量达到4%(w)时,催化剂具有较高的比表面积(99.6 m2•g-1), 催化剂的反应活化能为68.8 kJ•mol-1.在563 K, 1 MPa下,催化剂的最高催化活性和甲醇选择性分别为411.4 mg/gcat.•h和96.7%. TEM、TPR和TPD等表征结果显示,碳纳米管能增加Rh在催化剂表面的分散度,提高催化剂的还原温度并能增加氢物种的吸附量,这些结果将有助于更好地了解催化剂中各组分间的协同作用和催化活性中心本质. 相似文献
998.
3D-QSAR Study on Diindolylmethane and Its Analogues with Comparative Molecular Field Analysis(CoMFA)
Comparative molecular field analysis (CoMFA),a three dimensional quantitative structure-activity relationship (3D-QSAR) method was applied to a series of diindolylmethane(DIM) analogs to study the relationship between their structure and their induction of CYP 1A1-associated ethoxyresorufin-O-deethylase(EROD) activity.A DISCO model of pharmacophore was derved to guide the superposition of the compounds.The coefficient of cross-validation (q^2) and non cross-validation(r^2) for the model established by the study are 0.827 and 0.988 respectively,the value of variance ratio (F) is 103.53 and standard error estimate (SEE)is 0.044.These values indicate that the CoMFA model derived is significant and might have a good prediction for the catalytic activity of DIM compounds.As a consequence,the predicted activity values of new designed compounds were all higher than that of the reported value. 相似文献
999.
1000.
麝香草的新单萜配糖物的分离与合成 总被引:1,自引:0,他引:1
从麝香草(Thymus vulgaris L)的甲醇萃取物中分离出三个单萜配糖物. 用核磁共振光谱确定了它们的结构为对伞花-9-基-β-D-葡糖苷(1), 5-β-D-葡糖苷百里氢醌(2)和2-β-D-葡糖苷百里氢醌(3). 其中1是新化合物, 用以对伞花-9-醇为原料的对映体选择性合成方法确定了化合物1的8位的立体化学为R型. 相似文献