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排序方式: 共有373条查询结果,搜索用时 15 毫秒
61.
62.
Shota Ooi Takayuki Tanaka Kyu Hyung Park Dongho Kim Atsuhiro Osuka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(22):6645-6649
The oxidation of 10–10′ singly linked corrole dimers with DDQ at low concentration in CHCl3 afforded meso–meso, β–β, β–β triply linked 2H‐corrole dimers (with two inner NH groups in each corrole unit), which exhibited characteristic 1H NMR and absorption spectra attributable to their nonaromatic electronic networks. These 2H‐corrole dimers were reduced with NaBH4 to aromatic 3H‐corrole dimers, which were unstable and easily oxidized back to the 2H‐corrole dimers upon exposure to air. Bis(zinc(II)) complexes of the 2H‐corrole dimers were synthesized and characterized as rare examples of nonaromatic zinc(II) corrole complexes. 相似文献
63.
64.
The phase-transfer-catalyzed, highly enantioselective cyanation of aldimines using aqueous KCN has been realized based on the molecular design of chiral quaternary ammonium iodide 2c bearing a stereochemically defined tetranaphthyl backbone. For example, vigorous stirring of a mixture of cyclohexanecarboxaldimine (R = c-Hex) and (R,R,R)-2c (1 mol %) in toluene-KCN aqueous solution (1.5 equiv) at 0 degrees C for 2 h gave rise to the corresponding protected amino nitrile (R = c-Hex) in 89% yield with 95% ee. A wide range of aliphatic aldimines, including those having alpha-tert-alkyl substituents, is tolerated by the present system. This study represents a novel approach for the asymmetric Strecker-type reactions, which utilizes chiral phase-transfer catalysts for practical access to various unusual, optically pure alpha-amino acids. 相似文献
65.
Preparation of cerium-loaded Y-zeolites for removal of organic sulfur compounds from hydrodesulfurizated gasoline and diesel oil 总被引:8,自引:0,他引:8
Xue M Chitrakar R Sakane K Hirotsu T Ooi K Yoshimura Y Toba M Feng Q 《Journal of colloid and interface science》2006,298(2):535-542
Ce(IV)-loaded Y-zeolites (CeY) were prepared for selective removal of the trace amount of organic sulfur compounds from hydrodesulfurization (HDS)-treated diesel oil. The CeY samples can be obtained from NH4-Y-zeolite (NH4Y) using liquid-phase ion-exchange and solid-state ion-exchange methods. The ion-exchange reactions, structures, and selective adsorptions of organic sulfur compounds of the CeY samples were investigated using XRD, IR, XPS, TEM, and GC sulfur analyzer. The organic sulfur compound uptakes strongly depend on the amount and the valency of Ce in the zeolite structure. Ce(IV) shows much higher adsorptive ability than Ce(III). A CeY-S sample prepared by solid-state ion-exchange reaction of NH4Y and Ce(NO3)3 with Ce/NH4 mole ratio of 0.63 at 250 degrees C showed a maximum sulfur uptake from a model solution of HDS-treated gasoline containing thiophene [S = 5 ppm (ppm = mg/L)]. A desulfurization from a HDS-treated diesel oil containing organic sulfur compounds (S = 1.87 ppm) and H2S (S = 0.73 ppm) was investigated with a combination of the CeY-S and a CuO adsorbent for removal of H2S by a batch method. The sulfur content was reduced to below 0.01 ppm for the first time. This method provides a promising desulfurization process to prepare a clean fuel for fuel cells. 相似文献
66.
CJ Lombardo MS Glaz ZE Ooi DA Vanden Bout A Dodabalapur 《Physical chemistry chemical physics : PCCP》2012,14(38):13199-13203
Scanning confocal photocurrent microscopy has been used to characterize carrier collection efficiency in lateral bulk heterojunction devices. By analyzing the photocurrent mappings within these devices, the lateral extents of the space charge regions has been measured and reported. Modulation via white light bias or increased voltage bias is also shown to increase the size of the space charge regions. 相似文献
67.
James C. KnightRavi Prabaharan Angelo J. Amoroso Peter G. EdwardsLi-ling Ooi 《Polyhedron》2012,31(1):457-462
The new tripodal ligand tris(picolyl-2-carboxyamido-6-pyridyl) methanol (L1) has been synthesised via a Pd-catalysed amidocarbonylation reaction in good yield (64%). The ligand has been shown to readily form mononuclear complexes with both Fe(II) and Zn(II). Continuous Shape Mapping calculations have also been performed which confirm the ligands ability to enforce near-perfect trigonal prismatic co-ordination environments upon each of these metal ions. 相似文献
68.
Mohammad Ghaffari Mark Shannon H. Hui Ooi Kiang Tan Ahmad Irannejad 《Surface science》2012,606(5-6):670-677
In this report, SrTi(1 ? x)Fe(x)O(3 ? δ) photocatalyst powder was synthesized by a high temperature solid state reaction method. The morphology, crystalline structures of obtained samples, was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), respectively. The electronic properties and local structure of the perovskite STFx (0 ≤ x ≤ 1) systems have been probed by extended X-ray absorption fine structure (EXAFS) spectroscopy. The effects of iron doping level x (x = 0–1) on the crystal structure and chemical state of the STFx have been investigated by X-ray photoelectron spectroscopy and the valence band edges for electronic band gaps were obtained for STFx by ultraviolet photoelectron spectroscopy (UPS). A single cubic perovskite phase of STFx oxide was successfully obtained at 1200 °C for 24 h by the solid state reaction method. The XPS results showed that the iron present in the STFx perovskite structure is composed of a mixture of Fe3+ and Fe4+ (SrTi(1 ? x)[Fe3+, Fe4+](x)O(3 ? δ)). When the content x of iron doping was increased, the amount of Fe3+ and Fe4+ increased significantly and the oxygen lattice decreased on the surface of STFx oxide. The UPS data has confirmed that with more substitution of iron, the position of the valence band decreased. 相似文献
69.
An efficient asymmetric Mannich-type reaction of α-cyano α-sulfonyl carbanions has been achieved by exploiting the structural modularity and anion-recognition ability of chiral 1,2,3-triazolium ions. This protocol has proven to be applicable to a variety of N-Boc imines and cyanosulfones, affording β-amino α-cyanosulfones in excellent yields with high stereoselectivities. 相似文献
70.
Numerical differencing schemes are subject to dispersive and dissipative errors, which in one dimension, are functions of a wavenumber. When these schemes are applied in two or three dimensions, the errors become functions of both wavenumber and the direction of the wave. For the Euler equations, the direction of flow and flow velocity are also important. Spectral analysis was used to predict the error in magnitude and direction of the group velocity of vorticity–entropy and acoustic waves in the solution of the linearised Euler equations in a two‐dimensional Cartesian space. The anisotropy in these errors, for three schemes, were studied as a function of the wavenumber, wave direction, mean flow direction and mean flow Mach number. Numerical experiments were run to provide confirmation of the developed theory. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献