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991.
Sandrine Chalaye Elodie Bourgeat‐Lami Jean‐Luc Putaux Jacques Lang 《Macromolecular Symposia》2001,169(1):89-96
Encapsulation of silica nanoparticles was performed by dispersion polymerization of styrene, butyl acrylate and butyl methacrylate in aqueous alcoholic media. Following previous works1‐3), the silica beads were first modified by reacting on their surface the 3‐trimethoxysilyl propyl methacrylate coupling agent (MPS). In every case, the silica beads are all surrounded by polymer giving composite latex particles filled with silica. Each composite particle contains from one to a great number of silica beads. Changing the size or the concentration of the silica beads, and the experimental conditions for the synthesis of the polymer particles enables to control this number. One can take benefit of this to synthesize model composite particles with controlled compositions. 相似文献
992.
Ernesto Schulz Lang Clvis Peppe Renato A. Zan Ulrich Abram Ezequiel M. Vzquez‐Lpez Burkhard Krumm Oliver P. Ruscitti 《无机化学与普通化学杂志》2002,628(13):2815-2817
The novel mercury‐tellurium cluster [Hg8(μ‐n‐C3H7Te)12(μ2‐Br)Br3] is formed during the reaction of HgBr2 and (n‐C3H7Te)2Hg in DMSO. Its crystal structure has been elucidated showing [Hg8(μ‐n‐C3H7Te)12(μ2‐Br)]3+ units with a bromine‐centered distorted Hg8 cube. The mercury atoms are bridged by n‐C3H7Te— ligands and the resulting clusters are linked to a three‐dimensional network by bromine atoms. The close packing of the cluster is mainly determined by the flexible n‐propyl residues of the telluride building blocks. 相似文献
993.
The title compound is formed as a side‐product in the reaction of CF3CCl3 with Zn/DMF and dimethyl(thexyl)silyl chloride (=dimethyl(1,1,2‐trimethylpropyl)silyl chloride). The structure and the double‐bond configuration are deduced from its 13C‐NMR data. Its formation is discussed in terms of a Vilsmeier‐type formylation and a reductive elimination. 相似文献
994.
Existence or fixed point theorems, combined with interval analytic methods, provide a means to computationally prove the existence of a zero of a nonlinear system in a given interval vector. One such test is based on Borsuk's existence theorem. We discuss preconditioning techniques that are aimed at improving the effectiveness of this test. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
995.
The reaction of cis‐(2,2′‐bipyridine) Pt(CCPh)2 cis‐(4,4′‐dimethyl‐2,2′‐bipyridine) Pt‐(CCPh)2 and trans‐(Ph3P)2Pt(CCPh)2 towards different group 11 transition‐metal salts [M′X] (M′ = Cu, Ag; X = inorganic ligand) to give heterobimetallic or linear oligomeric and polymeric transition metal complexes is described. Different coordination modes for M′, PhCC, PPh3, and X were found in these species. The structural aspects as well as the preference for one coordination mode over another is discussed. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:521–533, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10097 相似文献
996.
以4-磺酸钾邻苯二腈为原料合成了水溶性四磺酸酞菁(H2PcTS)及其金属配合物(ZnPcTS, FePcTS, CoPcTS), 通过透析法提纯得到了纯度较高的产物. 采用傅里叶变换红外光谱(FTIR)、紫外-可见吸收光谱(UV-Vis)、核磁共振氢谱(1H NMR)及循环伏安(CV)等测试手段表征了四磺酸酞菁及其配合物的结构和性质. 结果表明, 磺酸酞菁在水溶液中存在不同程度的聚集现象, 金属离子的配位会对磺酸酞菁的光谱和电化学性质产生影响. 研究了磺酸酞菁作为光敏剂催化氧化1,5-萘二酚的反应, 发现FePcTS/H2O2催化体系对1,5-萘二酚具有良好的催化氧化性能, 氧化产物主要为5-羟基-1,4-萘醌. 比较了不同溶液pH值对FePcTS和H2PcTS催化能力的影响, 初步探讨了该反应的催化机理. 相似文献
997.
Holger Lang Margarete Gottlieb Michael Schwarz Silke Farkas BerndS. Schulz Frank Himmelsbach Ramamurthy Charubala Wolfgang Pfleiderer 《Helvetica chimica acta》1999,82(12):2172-2185
A series of new base-protected and 5′-O-(4-monomethoxytrityl)- or 5′-O-(4,4′-dimethoxytrityl)-substituted 3′-(2-cyanoethyl diisopropylphosphoramidites) and 3′-[2-(4-nitrophenyl)ethyl diisopropylphosphoramidites] 52 – 66 and 67 – 82 , respectively, are prepared as potential building blocks for oligonucleotide synthesis (see Scheme). Thus, 3′,5′-di-O-acyl- and N 2,3′-O,5′-O-triacyl-2′-deoxyguanosines can easily be converted into the corresponding O6-alkyl derivatives 6 , 8 , 10 , 12 , 14 , and 16 by a Mitsunobu reaction using the appropriate alcohol. Mild hydrolysis removes the acyl groups from the sugar moiety (→ 9 , 11 , 13 , 15 , and 19 (via 18 ), resp.) which can then be tritylated (→ 38 – 42 ) and phosphitylated (→ 57 – 61 ) in the usual manner. N 2-[2-(4-nitrophenyl)ethoxycarbonyl]-substituted and N 2-[2-(4-nitrophenyl)ethoxycarbonyl]-O6-[2-(4-nitrophenyl)ethyl]-substituted 2′-deoxyguanosines 5 and 7 , respectively, are synthesized as new starting materials for tritylation (→ 28 , 35 , and 37 ) and phosphitylation (→ 54 , 56 , 70 , and 78 ). Various O4-alkylthymidines (see 20 – 24 ) are also converted to their 5′-O-dimethoxytrityl derivatives (see 43 – 47) and the corresponding phosphoramidites (see 62 – 66 and 79 – 82 ). 相似文献
998.
Preparation and Crystal Structures of Neutral and Cationic Copper(I) Mixed Ligand Complexes with Triphenylphosphane and Derivatives of Biimidazole Eight triphenylphosphanecopper(I) complexes with bibenzimidazole, tetramethylbiimidazole or tetrahydrobiimidazole were prepared and characterized so far as possible by elemental analysis, IR, 1H-NMR and 31P-NMR spectra. The crystal structures of two complexes with bibenzimidazole were determined. [Cu(bbimH2)(PPh3)2]Cl · CH2Cl2: Reaction of CuCl with bibenzimidazole in fused triphenylphosphane or [CuCl(PPh3)3] with bibenzimidazole in CH2Cl2. Space group P 1, Z = 2, 6440 observed independent reflections, R = 0.064 for refletions with I > 2σ(I). Lattice parameters at 203 K: a = 983.6; b = 1348.9; c = 1805.5 pm; α = 77.24; β = 80.90; γ = 85.81°. The crystal structure is built up by monomeric molecules with distorted tetrahedral coordination of the copper atom (CuN2P2) and bibenzimidazole as bidentate ligand. The chloride ion is linked by H-bonds with the NH groups of the bibenzimidazole. [{Cu(PPh3)2}2(μ-bbim)] · 2 CH2Cl2: Reaction of [CuCl(PPh3)3] with the dipotassium salt of bibenzimidazole in CH3OH/CH2Cl2. Space group P 1, Z = 1, 7192 observed independent reflections, R = 0.057 for reflections with I > 2σ(I). Lattice parameters at 203 K: a = 1334.1; b = 1386.8; c = 1443.7 pm; α = 107.51; β = 103.35; γ = 113.74°. The crystal structure is built up by centrosymmetric molecules with distorted tetrahedral coordination of the copper atoms (CuN2P2) and bibenzimidazolate(2–) as tetradentate bridging ligand. 相似文献
999.
Ernesto Schulz Lang Ramo M. Fernandes Junior Edson T. Silveira Ulrich Abram Ezequiel M. Vzquez-Lpez 《无机化学与普通化学杂志》1999,625(8):1401-1404
The reactions between diphenyl ditelluride, (PhTe)2, or di(β-naphtyl)ditelluride, (β-naphtylTe)2, with equivalent amounts of iodine have been reinvestigated and the crystal and molecular structures of iodophenyltellurium(II), (PhTeI)4, and diiododi-(β-naphtyl)tellurium(IV), (β-naphtyl)2TeI2, have been determined. The structure of iodophenyltellurium(II) (space group Cc, a = 13.850(5) Å, b = 13.852(3) Å, c = 16.494(6) Å and β = 101.69(2)°, Z = 4) is built up by four PhTeI units which are linked by weak Te–Te interactions with Te–Te distances between 3.152(5) Å and 3.182(4) Å. The angles between the tellurium atoms are approximately 90° giving an almost perfect square. Long range secondary bonds (Te–I: about 4.2 Å) link the tetrameric units to give an infinite two-dimensional network. Iodo(β-naphtyl)tellurium(II) is less stable than the phenyl derivative. Solutions of this compound decompose under formation of elemental tellurium and (β-naphtyl)2TeI2. (β-Naphtyl)2TeI2 crystallises in the monoclinic space group C 2/c (a = 21.198(6) Å, b = 5.8921(8) Å, c = 16.651(5) Å, β = 114.77(2)°). The tellurium atom is situated on a two-fold crystallographic axis and Te–I and Te–C bond lengths of 2.899(1) and 2.108(7) Å have been determined. 相似文献
1000.
The compounds (NH4)2[(AuI4)(MI4)] (M = Ga, In) were obtained in sealed glass ampoules by reaction of I2, NH4I, Au and Ga or In as air‐sensitive black crystals. Both compounds crystallize in the orthorhombic space group Pnma (No. 62) and are isotypic: (NH4)2[(AuI4)(GaI4)], a = 12.619(2), b = 20.625(5) and c = 7.693(2) Å; (NH4)2[(AuI4)(InI4)], a = 12.587(2), b = 20.606(5) and c = 7.696(2) Å. The structures can be described as constituted of NH4+ cations and anionic zig zag chains of alternating tetrahedral MI4– (M = In, Ga) and square planar AuI4– units running along [010]. Within the chains, the MI4– ions form weak interactions with two of their I atoms to the AuI4– ions resulting in strongly elongated AuI6 octahedra. 相似文献