排序方式: 共有38条查询结果,搜索用时 46 毫秒
31.
通过间苯二甲醛与5-氟苯基二吡咯甲烷反应合成了一种新的间位苯基桥联的双咔咯1,并利用锰盐与自由咔咯反应制备了其锰的金属配合物2。采用紫外、质谱、核磁、XPS等手段对化合物进行了表征。以苯乙烯为底物考察了锰双咔咯2的催化氧化性质,探讨了时间、溶剂、氧源、轴向配体对催化反应的影响。结果表明以亚碘酰苯和间氯过氧苯甲酸为氧源时催化的主要产物为环氧苯乙烷,而以双氧水和叔丁基过氧化氢为氧源时则主要产物为苯甲醛;在极性溶剂中的催化氧化产率较高。轴向配体对催化氧化有促进作用,不同轴向配体对催化反应产率提高的顺序是:1-甲基咪唑 >吡啶 >咪唑。 相似文献
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Hans-Richard Sliwka 《Helvetica chimica acta》1999,82(2):161-169
The CD spectra of several 3-substituted azido-, amino-, thio-, phenylseleno- and (phosphonoseleno)-β,β-carotene derivatives with one or two stereogenic centers are discussed with respect to conformational changes of the cyclohexene end group. N- and S-Substituents (N3, NH2, SH) have no influence on the conformer equilibrium compared to O-substituents, whereas Se-substituents (SePh, SePO(OC3H7)2) slightly destabilize the preferred conformer of the β-end group. 相似文献
34.
DNA binding and nuclease activity of cationic iron(IV) and manganese(III) corrole complexes
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Yang Zhang Jin‐yan Wen Xiang‐li Wang Mian HR Mahmood Ze‐Yu Liu Hui Wang Liang‐nian Ji Hai‐yang Liu 《应用有机金属化学》2014,28(7):559-566
Cationic meso(4‐N‐methylpyridyl)‐based metallocorroles, μ‐oxo iron corrole dimer ( 1b ) and manganese corrole monomer ( 2b ), were synthesized and characterized. The interactions of these two metal corrole complexes with CT‐DNA were studied by UV–visible, fluorescence and circular dichroism spectroscopic methods, as well as by viscosity measurements. The results revealed that 1b interacts with CT‐DNA in a difunctional binding mode, i.e. non‐classical intercalation and outside groove binding with H‐aggregation, while 2b can interact with CT‐DNA via an outside groove binding mode only. The binding constants Kb of 1b and 2b were 4.71 × 105 m ?1 and 2.17 × 105 m ?1, respectively, indicating that 1b can bind more tightly to CT‐DNA than 2b . Furthermore, both complexes may cleave the supercoiled plasmid DNA efficiently in the presence of hydrogen peroxide or tert‐butyl hydroperoxide (TBHP), albeit 1b exhibited a little higher efficiency. The inhibitor tests suggested that singlet oxygen and high‐valent (oxo)iron(VI) corrole or (oxo)manganese(V) corrole might be the active intermediates responsible for the oxidative DNA scission. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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So far overlooked DMSO and DMF form long-lived radicals in the presence of small amounts of bases, DMF radicals being less stable than DMSO radicals. In solvent mixtures, the presence of DMSO prolonged the lifetime of DMF radicals. The occurrence of radicals may explain previously reported unexpected outcomes of reactions performed in these solvents. The commonly accepted inertness of these solvents towards minor quantities of alkali seems not to be warranted. 相似文献
36.
A listing of carotenoids with heteroatoms (X = F, Cl, Br, I, Si, N, S, Se, Fe) directly attached to the carotenoid carbon skeleton has been compiled. The 178 listed carotenoids with C, H, X atoms demonstrate that the classical division of carotenoids into hydrocarbon carotenoids (C, H) and xanthophylls (C, H, O) has become obsolete. 相似文献
37.
StineNalum Naess Arnljot Elgsaeter BenteJeanette Foss Baojun Li Hans‐Richard Sliwka Vassilia Partali ThorBernt Mel K.Razi Naqvi 《Helvetica chimica acta》2006,89(1):45-53
The surface and aggregation properties of the naturally occurring carotenoid crocin ( 1 ), examined through measurements of surface tension and UV/VIS absorption, have been used to determine the following parameters: critical aggregate concentration, surface‐saturation concentration, molecular area, free energy of adsorption and micellation, adsorption‐micellar energy relationship, equilibrium constants, and aggregate size. On structural grounds and based on the determined molecular area at the interface, the digentiobiosyl ester of the conjugated, highly unsaturated carotenoid diacid crocetin C20 : 7 should be classified as a bolaamphiphile. Crocin forms true monomolecular solutions in H2O; only at rather high concentrations aggregation occurs. 相似文献
38.
Sh. H. Abdel-Hafez H. W. Anthonsen H.-R. Sliwka V. Partali 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2217-2224
A simple and mild synthesis for pyrrolyl and pyrrolo[2, 3]pyrimidinyl diphenyl selenides is described based on the reaction of active methylene compounds with 4′-nitro-4-acetylaminodiphenyl selenide. The sensitivity of 77Se NMR spectra allowed differentiating the rather similar pyrrole compounds. The synthesized compounds were screened for their antifungal and antibacterial activities. 相似文献