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21.
We study a coarse-grained model of A(10)-B(20)-A(10) amphiphilic triblock copolymers in aqueous solution under confinement. We focus on the influence of the wall interaction on the morphology of the ensuing self-assembled structures. We also study the dynamics of the polymers. All our simulations are confined between two walls. We study three different combinations of walls: hydrophobic and hydrophobic, hydrophobic and hydrophilic, hydrophilic and hydrophilic. We moreover elucidate the concentration influence. The conformation and behavior of the copolymer in strongly confined systems depend on the type of wall interaction and concentration. 相似文献
22.
The authors have successfully developed a structurally coarse-grained 1,4-cis-polyisoprene-atactic polystyrene blend model by systematic mapping between a detailed atomistic model and a mesoscale model. This is to their best knowledge the first time that a chemically specific polymer blend model has been used to study the phase separation morphology and kinetics in a blend. A structurally optimized force-field model has many advantages over simple bead-spring models in terms of representing the chain microstructure. It keeps the identity of the polymers, particularly the structure through radial distribution functions. Starting from randomly mixed initial configurations, the blends show a clear phase separation for chain lengths around 10 monomers and this separation becomes more pronounced with the increase of chain length. The ensuing morphology is lamellar at equiweight concentrations and cylindrical or spherical at unbalanced concentrations. Morphologies are validated to be stable under increasing system sizes and further characterized quantitatively by density profiles. 相似文献
23.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
24.
PEGylated lipid membrane structure and phase behavior are important areas of study because of their potential in various biochemical, biomedical, and pharmaceutical applications. Here, we study mixed bilayers of DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) and PEGylated DOPCs (on phosphorus) in water using the MARTINI coarse-grained force field and show that the self-assembled structures can be changed between micelles and bilayers by applying different isotropic and semiisotropic (i.e., surface tension) pressure conditions. Radial distribution functions as well as radii of gyration confirm that structures are distinctly different. The results indicate that environmental conditions can be used to transform, manipulate, and eventually control lipid assemblies. 相似文献
25.
J W Faller B J Grimmond D G D'Alliessi 《Journal of the American Chemical Society》2001,123(11):2525-2529
The compounds (RRu)-[CyRuCl(S)-BINPO]SbF6 and [CyRuCl(S)-TolBINPO]SbF6 (Cy = eta6-cymene), were synthesized from (CyRuCl2)(2) and the appropriate non-C2-symmetric bisphosphine monoxide ligands (S)-BINPO and (S)-TolBINPO (BINPO = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) in the presence of NaSbF6. When these complexes were mixed with AgSbF6 the resulting Lewis acids catalyzed the Diels-Alder cycloaddition of cyclopentadiene and methacrolein. The product (2S)-methylbicyclo[2.2.1]hept-5-ene-2-carboxaldehyde was obtained with excellent diastereoselectivity (up to 99%) and enantioselectivity (up to 99%) in several cases. When the complexes containing the analogous C2-symmetric bisphosphine ligands (S)-BINAP and (S)-TolBINAP were employed as catalysts, the Diels-Alder cycloadducts were obtained with much lower enantioselectivity (19 to 50%) for the opposite antipode. Although some of the effect may arise from chelate ring size change, much of the enhanced stereoselectivity of (RRu)-[CyRuCl(S)-BINPO]SbF6 and [CyRuCl(S)-TolBINPO]SbF6 can be attributed to the electronic asymmetry at the stereogenic Ru center. 相似文献
26.
The stereochemistry and regiochemistry of nucleophilic addition to olefinic, allylic, or diene moieties can be controlled in reactions of molybdenum complexes. The synthesis of a wide range of -allylic cyclohexanones is feasible using (η5-cyclopentadienyl)Mo(CO)(NO)(allyl) cations. The stereoselective preparation of (RS,SR)-2-(1-methyl-2-butenyl)cyclohexanone from the reaction of 1-pyrrolidino-1-cyclohexene with [CpMo(CO)(NO)(η3-1,3-dimethylallyl)]BF4 illustrates the methodology. 相似文献
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