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81.
Immobilized copper(Ⅱ) in organic-inorganic hybrid materials catalyzed Ar-N coupling of arylboronic acids with imidazoles has been developed. Arylboronic acids reacted with imidazoles smoothly in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper(Ⅱ) catalyst (10 mol%) in methanol without any additives and bases. The reactions generated the corresponding cross-coupling products in good yields. Furthermore, silica-supported copper can be recovered and recycled by a simple filtration procedure and used for five consecutive trials without decreases in activity. 相似文献
82.
83.
High nuclearity paramagnetic, spin-coupled transition metal clusters and grids are fascinating chemists and physicists partly because of their structural beauty, and the challenge of creating them, but also because of their novel physical properties. Magnetic interactions between the spin centers are a primary focus. This review will examine a selection of Mn(II) polynuclear grids and clusters, with nuclearities in the range Mn4 to Mn9. Theoretical treatments of the magnetic properties are discussed, and approaches to solving the exchange problem for ‘large’ spin systems related to computational difficulties. A freely available software package (MAGMUN4.1) is presented as a means of dealing simply with spin-coupled clusters in general, and symmetry reduction methods are discussed briefly as a means of dealing with ‘large’ spin systems. 相似文献
84.
四(三苯基膦)化钯催化的若干菲啶类化合物的合成 总被引:1,自引:0,他引:1
邻甲酰基芳基硼酸与取代邻溴苯胺经四(三苯基膦)化钯催化偶联缩合, 合成了9个菲啶衍生物。邻溴苯胺的取代基无论是吸电子或供电子基团, 反应均可顺利进行。 相似文献
85.
86.
A novel dual stage chemiluminescence detection system incorporating individually controlled hot stages has been developed and applied to probe for material interaction effects during polymer degradation. Utilization of this system has resulted in experimental confirmation for the first time that in an oxidizing environment a degrading polymer A (in this case polypropylene, PP) is capable of infecting a different polymer B (in this case polybutadiene, HTPB) over a relatively large distance. In the presence of the infectious degrading polymer A, the thermal degradation of polymer B is observed over a significantly shorter time period. Consistent with infectious volatiles from material A initiating the degradation process in material B it was demonstrated that traces (micrograms) of a thermally sensitive peroxide in the vicinity of PP could induce degradation remotely. This observation documents cross-infectious phenomena between different polymers and has major consequences for polymer interactions, understanding fundamental degradation processes and long-term aging effects under combined material exposures. 相似文献
87.
Guldi DM Hirsch A Scheloske M Dietel E Troisi A Zerbetto F Prato M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(20):4968-4979
Control over the interchromophore separation, their angular relationship, and the spatial overlap of their electronic clouds in several ZnP-C(60) dyads (ZnP=zinc porphyrin) is used to modulate the rates of intramolecular electron transfer. For the first time, a detailed analysis of the charge transfer absorption and emission spectra, time-dependent spectroscopic measurements, and molecular dynamics simulations prove quantitatively that the same two moieties can produce widely different electron-transfer regimes. This investigation also shows that the combination of ZnP and C(60) consistently produces charge recombination in the inverted Marcus region, with reorganization energies that are remarkably low, regardless of the solvent polarity. The time constants of electron transfer range from the mus to the ps regime, the electronic couplings from a few tens to several hundreds of cm(-1), and the reorganization energies remain below 0.54 eV and can be as low as 0.16 eV. 相似文献
88.
Wei Wang Rongliang Wang Fan Wu Boshun Wan 《Reaction Kinetics and Catalysis Letters》2005,85(2):277-282
Summary A Ni-promoted ligand free palladium catalyst system for Suzuki coupling of aryl bromides has been developed in high efficiency under mild reaction conditions. It was obtained in situ by introducing NiCl2 to PdCl2/PVP using a parallel high-throughput screening technique. A wide range of aryl bromides bearing a variety of functional groups was evaluated. 相似文献
89.
介绍了对尿汞快速测定法的改进,用消泡剂磷三丁酸消除尿中泡沫,并讨论了尿汞测定的最佳条件,本法的相对标准偏差为4.8-9.0%,回收率94-101%。 相似文献
90.
Zhende Liu 《Tetrahedron》2007,63(9):1931-1936
A flexible method for the synthesis of 5,6-disubstituted furo[2,3-d]pyrimidine derivatives is described. The key step is a palladium-catalyzed arylative cyclization of alkynylpyrimidinols with various aryl iodides, which gave the title compounds in 36-75% yield. 相似文献