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41.
Inside Cover: Supramolecular Complexes of Multivalent Cholesterol‐Containing Polymers to Solubilize Carbon Nanotubes in Apolar Organic Solvents (Chem. Asian J. 5/2014)
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Using split/pool encoded synthesis and a colorimetric catalysis assay, a number of synthetic phosphatase catalysts were developed. 相似文献
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Interference between dipolar interactions in covalently linked (13)C-(1)H and nonlinked (1)H-(1)H pairs can be used to generate antiphase magnetization between noncoupled spins. The buildup rate of such antiphase terms is highly sensitive to local geometry, in particular the interproton distance and the (13)C-(1)H-(1)H internuclear angle. These rates have been measured for opposing C(alpha)H(alpha) pairs in antiparallel beta-sheets in the third Igg-binding domain of protein G (GB3) and in HIV protease, complexed with the inhibitor DMP323. For GB3, good agreement with the 1.1-A crystal structure is found. However, this agreement rapidly deteriorates with decreasing resolution of the corresponding X-ray structure. For HIV protease, two separate crystal structures that differ by less than 0.2 A from one another exhibit lower agreement in their predicted cross-correlated relaxation rates relative to one another than is found between experimental rates and the average of the rates predicted for the two structures. These data indicate that quantitative measurement of these cross-correlated relaxation rates can provide highly accurate structural information in macromolecules. 相似文献
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The high temperature metal-insulator transition in pure V2O3 has been investigated by nuclear magnetic resonance and relaxation. The relaxation rate in the range 160–320K was found to satisfy the Korringa relaxation and at temperature above 550K to be constant as expected for a paramagnetic insulator. In the intermediate temperature range the high field resonance line shape showed broadening which we interpret as due to the coexistence of a metallic and an insulating phase. 相似文献
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The rates of hydrogenation of several styrene derivatives by stoichiometric hydridocobalt tetracarbonyl [HCo(CO)4] were measured and compared. The relative rates are discussed in terms of conjugative and steric effects on the geminate radical pair mechanism. An improved method for determining HCo(CO)4 concentration is described. 相似文献
49.
Jerome Hollander Floyd D. Trischler Rex B. Gosnell 《Journal of polymer science. Part A, Polymer chemistry》1967,5(11):2757-2767
A number of polyurethanes based on fluorinated aliphatic diisocyanates, perfluorinated aromatic diisocyanates, and chlorinated aromatic diisocyanates have been prepared. The polyurethane prepared from perfluorotrimethylene diisocyanate and hexafluoropentanediol was a rubbery solid which hydrolyzed readily in air to a liquid or sticky solid but was stable if protected from moisture. The products of hydrolysis were isolated and identified. Polyurethanes based on hexafluoropentamethylene diisocyanate were synthesized by reaction of hexafluoropentanediamine with hexafluoropentamethylene bischloroformate and with tetrafluoro-p-phenylene bischloroformate. Polyurethanes were synthesized by reaction of tetrafluoro-p-phenylene diisocyanate with hexafluoropentanediol and pentanediol. Other perfluoroaryl diisocyanate-based polyurethanes were synthesized by reaction of tetrafluoro-m-phenylene diisocyanate with hexafluoropentanediol and with tetrafluoro-p-hydroquinone. Polyurethanes were also synthesized by reaction of tetrachloro-p-phenylene diisocyanate and 2,3,5,6-tetrachloro-p-xylylene-α,α′-diisocyanate with hexafluoropentanediol. 相似文献
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Chemical reactions and processes often involve chiral, yet racemic, cationic reagents, intermediates or products. To afford instead non racemic or enantiopure compounds, an asymmetric ion pairing of the cations with enantiopure anions can be considered--the counter ions behaving as asymmetric auxiliaries, ligands or reagents. Detailed herein is a short review of our approach towards gaining reliable and predictable control over stereoselective ion pairing phenomena through the synthesis and the use of novel configurationally stable hexacoordinated phosphate anions. 相似文献