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991.
A modular sugar-based phosphoroamidite ligand library for the Ni-catalyzed trialkylaluminium addition to aldehydes has been synthesized and screened. After systematic variation of the sugar backbone, the substituents at the phosphoroamidite moieties and the flexibility of the ligand backbone, the monophosphoroamidite ligand 3-amine-3-deoxy-1,2:5,6-di-O-isopropylidene-((3,3′-di-trimethylsilyl-1,1′-biphenyl-2,2′-diyl)phosphite)-α-d-glucofuranose 1d were found to be optimal. Activities were high and enantioselectivities were good (ees up to 78%) for several aryl aldehydes. 相似文献
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996.
Lucas Montero de Espinosa Michael A. R. Meier Juan C. Ronda Marina Galià Virginia Cádiz 《Journal of polymer science. Part A, Polymer chemistry》2010,48(7):1649-1660
An α,ω‐diene containing hydroxyl groups was prepared from plant oil‐derived platform chemicals. The acyclic diene metathesis copolymerization (ADMET) of this monomer with a phosphorus‐containing α,ω‐diene (DOPO II), also plant oil derived, afforded a series of phosphorus containing linear polyesters, which have been fully characterized. The backbone hydroxyls of these polyesters have been acrylated and radically polymerized to produce crosslinked polymers. The thermomechanical and mechanical properties, the thermal stability, and the flame retardancy of these phosphorus‐based thermosets have been studied. Moreover, methyl 10‐undecenoate has been used as chain stopper in selected ADMET polymerizations to study the effect of the prepolymers' molecular weights on the different properties of the final materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1649–1660, 2010 相似文献
997.
Nenad Antoni? 《Journal of Mathematical Analysis and Applications》2008,343(1):207-225
Since their introduction H-measures have been mostly used in problems related to propagation effects for hyperbolic equations and systems. In this study we give an attempt to apply the H-measure theory to other types of equations. Through a number of examples we present how do the differences between parabolic and hyperbolic equations reflect in the properties of H-measures corresponding to the solutions. Secondly, we apply the H-measures to the Schrödinger equation, where we succeed in proving a propagation property. However, our conclusion is that a variant of H-measures should be sought which would be better suited to parabolic problems. We propose such a variant, show some fundamental properties and illustrate its applicability by some examples. In particular, we show that the variant provides new information in a number of situations where the original H-measures did not. Finally, we describe how the new variant can be used in small amplitude homogenisation of parabolic equations. 相似文献
998.
Fukuzumi S Mandal S Mase K Ohkubo K Park H Benet-Buchholz J Nam W Llobet A 《Journal of the American Chemical Society》2012,134(24):9906-9909
Four-electron reduction of O(2) by octamethylferrocene (Me(8)Fc) occurs efficiently with a dinuclear cobalt-μ-1,2-peroxo complex, 1, in the presence of trifluoroacetic acid in acetonitrile. Kinetic investigations of the overall catalytic reaction and each step in the catalytic cycle showed that proton-coupled electron transfer from Me(8)Fc to 1 is the rate-determining step in the catalytic cycle. 相似文献
999.
A novel amperometric bienzymatic biosensor has been developed based on the incorporation of Lactate Oxidase (LOx) and Horseradish Peroxidase (HRP) into a carbon nanotube/polysulfone membrane by the phase inversion technique onto screen-printed electrodes (SPEs). In order to improve the sensitivity and reduce the working potential, experimental conditions have been optimized and ferrocene has also been incorporated into the membrane as a redox mediator of the enzymatic reactions, which allows the reduction of H(2)O(2) at -100 mV. Measurements were carried out in phosphate buffer solution at pH 7.5 and under batch conditions. The biosensor response time to L-lactate was only 20 s and showed a good reproducibility (RSD 2.7%). Moreover, the detection limit was 0.05 mg L(-1) of l-lactate with a linear interval range from 0.1 mg L(-1) to 5 mg L(-1). Finally, the biosensor has been applied to the determination of l-lactic acid in different wine and beer samples. Then, the results obtained with the biosensor were compared with the ones obtained using, as a reference method, a commercial kit based on spectrophotometric measurements, obtaining an excellent agreement between the results, validating our approach. 相似文献
1000.
W Buchowicz B Herbaczyńska LB Jerzykiewicz T Lis S Pasynkiewicz A Pietrzykowski 《Inorganic chemistry》2012,51(15):8292-8297
A new hexanuclear cyclopentadienylnickel carbide cluster (NiCp)(6)(μ(6)-C) (1) was obtained through the thermolysis of the alkene complex [NiCp(CH(3))(η(2)-CH(2)═CHC(4)H(9))] (4). The X-ray molecular structure of 1 (monoclinic; P2(1)/c; Ni-C(carbide) = 1.767(4)-2.109(4) ?) reveals a highly deformed octahedral arrangement of nickel atoms with two octahedron edges opened (Ni-Ni bonding distances = 2.410(1)-2.623(1) ?, Ni···Ni nonbonding distances = 3.107(2) and 3.108(2) ?). Cluster 1 is the first example of a homoleptic, cyclopentadienylnickel carbide cluster. Moreover, (13)C-labeling studies proved that the carbido ligand in cluster 1 originated from the Ni-bound methyl group. This transformation requires a triple C-H bond activation in the methyl group, which has not been observed so far for late transition metal compounds. 相似文献