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Abachi S Baringer P Bylsma BG DeBonte R Koltick D Loeffler FJ Low EH McIlwain RL Miller DH Ng CR Rangan LK Shibata EI Derrick M Gan KK Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Weiss JM Wood DE Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Kesten P Meyer DI Nitz D Seidl AA Thun R Willutzky M Cork B 《Physical review letters》1986,57(16):1990-1993
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By use of salt elimination, the transition metal substituted oligosilanes (η5-C5Me4Et)Fe(CO)2SiMe2SiMe2Cl 1, (η5-C5Me4Et)Mo(CO)3SiMe2SiMe2Br 2, (η5-C5Me4Et)Fe(CO)2(SiMe2)6(CO)2Fe(η5-C5Me4Et) 3 and (η5-C5Me4Et)Fe(CO)2(SiMe2)6Br 4 were prepared and characterized. Compound 1 is well crystallized from pentane and its structure has been determined by X-ray diffraction analysis. 相似文献
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cis-Bisfullerene[60] adducts of 6,13-disubstituted pentacenes (R = Ph, 4'-hydroxymethylphenyl) are synthesized in 75% to 85% isolated yields under kinetically controlled Diels-Alder conditions. The cycloadditions are completely regioselective and highly stereoselective, with only traces of the diastereomeric trans-bisfullerene[60] adducts forming. 相似文献
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Yu Yang Maya Belghazi Arnaud Lagadec David J. Miller Steven B. Hawthorne 《Journal of chromatography. A》1998,810(1-2):149-159
The intermolecular interactions between organic solutes and sorbent matrices under subcritical water conditions have been investigated at a pressure of 50 bar and temperatures ranging from 50 to 250°C. Both polar and nonpolar organics (chlorophenols, amines, n-alkanes, and polycyclic aromatic hydrocarbons) and five different sorbent matrices (glass beads, alumina, Florisil, silica-bonded C18, and polymeric XAD-4 resins) were used. From the same matrix, the polar solutes always eluted at lower temperatures, while the moderately polar and nonpolar solutes only eluted at higher temperatures. Similar to matrix effects previously observed using supercritical carbon dioxide, the sorbent type greatly influenced the elution efficiency under subcritical water conditions. Lower temperatures are sufficient to elute a particular solute from glass beads, alumina, and Florisil, but higher temperatures (less polar water) are needed to elute the same solute from silica-bonded C18. The highest temperatures were required to elute aromatic organics from XAD-4. These matrix effects demonstrate that, while low temperature water can break inert or dipole interactions between solutes and glass beads, alumina, and Florisil, higher temperature water is required to interrupt the van der Waals attractions between solutes and silica-bonded C18, and even higher temperatures needed to overcome the π-electron interactions between aromatic solutes and XAD-4. 相似文献
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Miller CR Vogel R Surawski PP Jack KS Corrie SR Trau M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(21):9733-9740
Thiol-functionalized organosilica microspheres were synthesized via a two-step process: (1) acid-catalyzed hydrolysis and condensation of 3-mercaptopropyltrimethoxysilane (MPTMS), followed by (2) base-catalyzed condensation, which led to the rapid formation of emulsion droplets with a narrow size distribution. These droplets continued to condense to form solid microspheres. Solution (29)Si NMR and optical microscopy were applied to study the mechanism of this novel synthetic route. Solid-state (29)Si NMR, SEM, zeta potential titration, and Coulter counter measurements were used to study the bulk and surface properties and to determine the particle size distributions of the final microspheres. Compared to conventional St?ber silica particles, these microspheres were shown to have a lower degree of cross-linking (average degree of condensation, r = 1.25), a larger average size (up to 6 microm), and a higher isoelectric point (pH = 4.4). Confocal microscopy of dye-labeled microspheres showed an even distribution of dye molecules throughout the interior, characteristic of a readily accessible and permeable organosilica network. These findings have implications for the production of functionalized solid supports for use in catalysis and biological applications, such as optically encoded carriers for combinatorial synthesis. 相似文献