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211.
212.
Uro Groelj Ale Drobni
Simon Re
nik Jurij Svete Branko Stanovnik Amalija Golobi
Nina Lah Ivan Leban Anton Meden Simona Goli
‐Grdadolnik 《Helvetica chimica acta》2001,84(11):3403-3417
Cycloadditions of various 1,3‐dipoles to (5Z)‐1‐acyl‐5‐(cyanomethylidene)‐3‐methylimidazolidine‐2,4‐diones 8 or 9 , prepared in 3 steps from hydantoin ( 1 ) (Schemes 1 and 2), were studied. In all cases, reactions proceeded regio‐ and stereoselectively. The type of product depended on the 1,3‐dipole and/or dipolarophile employed as well as on reaction conditions. Thus, with stable dipoles under neutral conditions, spirohydantoin derivatives 12 – 16 were obtained (Scheme 2), while under basic or acidic conditions, pyrazole‐ or isoxazole‐5‐carboxamides 18 and 23 – 26 and carboxylate 27 were formed via aromatization of the newly formed dihydroazole ring, followed by the simultaneous cleavage of the hydantoin ring (Schemes 3 – 5). 相似文献
213.
214.
215.
Katharina Landfester Nina Bechthold Stephan Frster Markus Antonietti 《Macromolecular rapid communications》1999,20(2):81-84
A combination of small‐angle neutron scattering (SANS), conductivity, and surface tension measurements is used to show that the primary droplets in miniemulsion polymerization have the same size and the same size distribution as the final particles. It is also shown that hexadecane employed as a cosurfactant is homogeneously dispersed in the droplets and does not possess any interface activity. The presented data support that a 1 : 1 copy from monomer droplets to polymer particles is achieved. 相似文献
216.
Vladimir A. Bershtein Pavel N. Yakushev Nina N. Peschanskaya 《Macromolecular Symposia》1999,147(1):73-82
An original laser-interferometric creep rate spectroscopy method was applied to analysis of molecular motion in some polymers, composites and interpenetrating polymer networks. Its potentials for study of nanoscale dynamic/compositional heterogeneity in complex systems, of a peculiar relaxation behavior of polymer binder in composites, and for prediction of temperature anomalies in strength are demonstrated. 相似文献
217.
Mixed iron and molybdenum oxide catalysts supported on nanostructured silica, SBA-15, were synthesized with various Mo/Fe atomic ratios ranging from 0.07/1.0 to 0.57/1.0. Structural characterization of as-prepared MoxOy_FexOy/SBA-15 samples was performed by nitrogen physisorption, X-ray diffraction, and DR-UV-Vis spectroscopy. Adding molybdenum resulted in a pronounced dispersion effect on supported iron oxidic species. Increasing atomic ratio up to 0.21Mo/1.0Fe was accompanied by decreasing species sizes. Strong interactions between iron and molybdenum during the synthesis resulted in the formation of Fe−O−Mo structure units, possibly Fe2(MoO4)3-like species. Reducibility of MoxOy_FexOy/SBA-15 catalysts was investigated by temperature-programmed reduction experiments with hydrogen as reducing agent. The lower reducibility obtained when adding molybdenum was ascribed to both dispersion and electronic effect of molybdenum. Catalytic performance of MoxOy_FexOy/SBA-15 samples was studied in selective gas-phase oxidation of propene with O2 as oxidant. Adding molybdenum resulted in an increased acrolein selectivity and a decreased selectivity towards total oxidation products. 相似文献
218.
Dmitry Yu. Naumov Marina I. Naumova Nina V. Podberezskaya Natalia V. Kuratieva 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):i73-i75
The structures of monoclinic (C2/m) lithium dihydrogenphosphate, LiH2PO2, and tetragonal (P41212) beryllium bis(dihydrogenphosphate), Be(H2PO2)2, have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of hypophosphite anions and metal cations in tetrahedral coordination by O atoms. Within the layers, the anions bridge four Li+ and two Be2+ cations, respectively. In LiH2PO2, the Li atom lies on a twofold axis and the H2PO2− anion has the PO2 atoms on a mirror plane. In Be(H2PO2)2, the Be atom lies on a twofold axis and the H2PO2− anion is in a general position. 相似文献
219.
The synthesis, structural chemistry and magnetic properties of a series of new Cu(II) polymers with α,ω-dicarboxylic acids (sebacic (H2seb), suberic (H2sub), succinic (H2suc) and adipic (H2adip)) and 3-aminopyridine (3-apy) are described: [Cu(Hsub)2(3-apy)2·2CH3OH]n (1); [Cu(Hseb)2(3-apy)2·4CH3OH]n (2); [Cu(Hsuc)2(3-apy)2]n (3); [Cu(adip)(3-apy)2]n·n(H2adip) (4). All four compounds feature a bis-monodentate bridging mode of the coordinated dicarboxylate moiety. Compounds 1 and 2 exhibit linear chains, whereas compound 3 shows two-dimensional structure. The 3-apy ligand acts as terminal ligand in 1–3. Compound 4 contains a doubly deprotonated adipate (adip2−) that connects Cu centers into linear chains. Additionally, 3-apy acts as a bridge in 4, resulting in the formation of parallel two-dimensional layers distant enough to host neutral molecules of adipic acid. Magnetic susceptibility measurements of compounds 1 and 3 show Curie law behavior indicating that the S = 1/2 Cu(II) spin carriers are magnetically well isolated by the dicarboxylate ligands. 相似文献
220.
Here we report the synthesis and physicochemical characterization of novel hybrid core/shell type ZnO/poly(ethylcyanoacrylate)
colloidal particles. It is expected that coating ZnO colloidal particles with biocompatible and biodegradable poly(alkylcyanoacrylates)
will pave the way toward the potential application of ZnO colloidal particles in biomedical research. Recent findings of cell
selective toxicity indicate a potential utilization of ZnO colloidal particles in the treatment of cancer. For this purpose,
ZnO colloidal particles have to be selectively delivered to the site of action by a suitable biocompatible and biodegradable
carrier system. Toward this goal, poly(alkylcyanoacrylates) meet ideally the requirements for carrier systems in drug delivery
due to their biocompatibility, biodegradability, low toxicity, and ability to overcome the multidrug resistance in cancer
cells. 相似文献