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991.
Gonçalo A. S. Dias Juha H. Videman 《Mathematical Methods in the Applied Sciences》2015,38(17):4038-4051
We consider the coupled problem describing the motion of a linear array of three‐dimensional obstacles floating freely in a homogeneous fluid layer of finite depth. The interaction of time‐harmonic waves with the floating objects is analyzed under the usual assumptions of linear water‐wave theory. Quasi‐periodic boundary conditions and a simplified reduction scheme turn the system into a linear spectral problem for a self‐adjoint operator in Hilbert space. Based upon the operator formulation, we derive a sufficient condition for the nonemptiness of its discrete spectrum. Various examples of obstacles that generate trapped modes are given. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
992.
993.
Jia Sun Peicheng Zhang Qi Wei Hang Xun Feng Tang Yongde Yue Li Li Xuefeng Guo Rong Zhang 《Tetrahedron letters》2014
Amarusine A (1), a new polyketide derivative possessing an unusual dioxaspiro[4.4]nonane derivative with a butyrolactone ring, was isolated from the leaves of Pleioblastus amarus. The structure and absolute stereochemistry of compound 1 were rigorously determined using UV, IR, HRESIMS, and 1D and 2D NMR techniques and by comparing experimental and calculated electronic circular dichroism (ECD) spectra. Amarusine A (1) exhibits a good antioxidant activity for scavenging the DPPH radical. A possible biosynthetic pathway was postulated. 相似文献
994.
Benren Liao Libo Ruan Min Shi Nian LiLiang Chang Leping LiuFan Yang Jie Tang 《Tetrahedron letters》2014
An efficient method for preparation of 3-formyl-2-arylbenzo[b]furan derivatives 4 from 3-chloro-2-(2-methoxyaryl)-1-arylprop-2-en-1-one 2 was developed, and the desired product was obtained in good to excellent yields. By converting 2-(2-methoxyphenyl)-3-oxo-3-phenylpropanal 1 to 2, the regioselectivity problem occurring in the reaction when using 1 as the starting material was successfully avoided. Furthermore, a one-pot procedure for the successive demethylation, cyclization, and hydrolysis was evolved, although the intermediate 3-(dibromomethyl)-2-phenylbenzo[b]furan 3a could be isolated. A plausible mechanism was proposed based on some in situ investigations. 相似文献
995.
Long Tang Liang Bai Yaping Duan Wei Xia Wenwen Dong Dongsheng Li 《无机化学与普通化学杂志》2014,640(11):2268-2273
Three ZnII and CdII complexes with Y‐shaped dicarboxylate ligands, namely [Zn(L1)(2,2′‐bpy)2(H2O)] · 2H2O ( 1 ), [Zn(L1)(bpp)(H2O)] ( 2 ), and [Cd(L1)(H2O)] · H2O ( 3 ) [H2L1 = N‐phenyliminodiacetic acid, 2,2′‐bpy = 2,2′‐bipyridine, bpp = 1,3‐bis(4‐pyridyl)propane] were synthesized and characterized by elemental analysis, IR spectroscopy single‐crystal X‐ray diffraction, and thermogravimetric analyses. Compound 1 shows an hydrogen‐bonded 2D network, whereas compound 2 is an infinite 1D wavy chain structure, though O–H ··· O hydrogen‐bonded to form a 2D network. Compound 3 displays a 2D uninodal 3‐connected Shubnikov plane net with the point symbol of (4.82). Moreover, the solid‐state such as thermal stabilities and fluorescence properties of 1 – 3 were also investigated. 相似文献
996.
M. Salih Ağırtaş Emrah Dede Selçuk Gümüş Abdurrahman Dündar Veysi Okumuş 《无机化学与普通化学杂志》2014,640(10):1953-1959
A novel phthalonitrile derivative bearing 2‐isopropyl‐6‐methylpyrimidin‐4‐yloxy substituents at peripheral positions was synthesized by a nucleophilic substitution reaction. Metallophthalocyanines were obtained from the reaction of the novel phthalonitrile with metal Zn, Cu, Co, and Ni salts. The characterization of the compounds was performed using elemental analysis as well as UV/Vis, FT‐IR, and 1H‐NMR spectroscopy. The aggregation behaviors of phthalocyanine complexes were also investigated. These metallophthalocyanines do not show any aggregation behavior between 10–4–10–6 M concentration range in THF. The antioxidant activities of the synthesized compounds were evaluated using three different tests: 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, metal chelating activity, and reducing power assays. All the compounds exhibited various antioxidant activities. In addition, antimicrobial activity of the compounds was tested over four gram positive and two gram negative bacteria. Moreover, the ground‐state geometries of the complexes were optimized using density functional theory (DFT) methods at B3LYP/6‐31G(d, p) level in order to obtain information about the 3D arrangements and electronic structure. 相似文献
997.
998.
Yan‐Xue Chen Kang‐Kang Tang Xin Wang Bing‐Yi Chen Guo‐Qiang Qin Jin‐Hui Yang 《无机化学与普通化学杂志》2014,640(11):2292-2295
The zinc(II) coordination polymer [Zn3(BPT)2(μ2‐H2O)2(H2O)2]n · n(DMA) ( 1 ) (H3BPT = biphenyl‐3,4′,5‐tricarboxylic acid, DMA = N,N′‐dimethylactamide) was obtained by the solvothermal reaction of H3BPT with Zn(NO3)2 in DMA/H2O mixed solvent. Single crystal X‐ray analysis reveals that compound 1 has a complicated 3D framework containing linear trinuclear [Zn3(COO)4(μ2‐H2O)2] clusters as building subunits, which can be simplified into a (3,6)‐connected rtl topological network with the Schläfli symbol {4.62}2{42.610.83}. The calculated results of total and partial density of states (DOS) indicate that the luminescence of 1 mainly originates from intraligand charge transfer. 相似文献
999.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of N?H Imines and Alkynes by C?H/N?H Activation
Ruoyu He Zhi‐Tang Huang Qi‐Yu Zheng Congyang Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(19):5050-5053
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献
1000.
Conghui Tang Ning Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(25):6646-6650
A novel copper‐catalyzed aerobic oxidative C(CO) C(alkyl) bond cleavage reaction of aryl alkyl ketones for C N bond formation is described. A series of acetophenone derivatives as well as more challenging aryl ketones with long‐chain alkyl substituents could be selectively cleaved and converted into the corresponding amides, which are frequently found in biologically active compounds and pharmaceuticals. 相似文献