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111.
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Large‐Scale Synthesis of Enantiopure Molecular Cages: Chiroptical and Recognition Properties
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Sara Lefevre Dawei Zhang Estelle Godart Marion Jean Dr. Nicolas Vanthuyne Jean‐Christophe Mulatier Dr. Jean‐Pierre Dutasta Dr. Laure Guy Prof. Alexandre Martinez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):2068-2074
A convenient and efficient gram‐scale synthesis for enantiopure hemicryptophane–tren (tren=tris(2‐aminoethyl)amine) derivatives has been developed. The four‐step synthesis is based on the optical resolution of a key intermediate, cyclotriveratrylene, for which the energy barrier for racemization has been measured to ensure that no racemization occurs during the two last steps of the synthetic pathway. The assignments of the absolute configurations have been performed by electronic circular dichroism and the enantiopurity was determined by NMR spectroscopy in the presence of enantiopure camphor sulfonic acid. To highlight the interest of such compounds, the recognition of norephedrine neurotransmitter was investigated and showed a remarkable enantioselectivity towards the C3 symmetrical hosts. Finally, this highly modular synthetic pathway was used to provide eight enantiopure hemicryptophanes with different sizes, shapes, and functionalities. These results underline the high potential of this approach, which could lead to many applications in chiral recognition or asymmetric supramolecular catalysis. 相似文献
113.
Linear bis dithiocarbamates are conveniently obtained from symmetrical disubstituted α,ω-alkanediamines whose preparation is reported. 相似文献
114.
Importance of the Correlation between Width and Length in the Shape Analysis of Nanorods: Use of a 2D Size Plot To Probe Such a Correlation
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Prof. Clément Roux Dr. Céline Delmas Prof. Jean‐Daniel Marty Dr. Myrtil L. Kahn Dr. Christophe Mingotaud 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12424-12429
Analysis of nanoparticle size through a simple 2D plot is proposed in order to extract the correlation between length and width in a collection or a mixture of anisotropic particles. Compared to the usual statistics on the length associated with a second and independent statistical analysis of the width, this simple plot easily points out the various types of nanoparticles and their (an)isotropy. For each class of nano‐objects, the relationship between width and length (i.e., the strong or weak correlations between these two parameters) may suggest information concerning the nucleation/growth processes. It allows one to follow the effect on the shape and size distribution of physical or chemical processes such as simple ripening. Various electron microscopy pictures from the literature or from the authors′ own syntheses are used as examples to demonstrate the efficiency and simplicity of the proposed 2D plot combined with a multivariate analysis. 相似文献
115.
Christophe Lacave Toan T. Nguyen Benoit Pausader 《Journal of Mathematical Fluid Mechanics》2014,16(2):375-406
We investigate the influence of the topography on the lake equations which describe the two-dimensional horizontal velocity of a three-dimensional incompressible flow. We show that the lake equations are structurally stable under Hausdorff approximations of the fluid domain and L p perturbations of the depth. As a byproduct, we obtain the existence of a weak solution to the lake equations in the case of singular domains and rough bottoms. Our result thus extends earlier works by Bresch and Métivier treating the lake equations with a fixed topography and by Gérard-Varet and Lacave treating the Euler equations in singular domains. 相似文献
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Christophe Weibel 《Discrete and Computational Geometry》2012,47(3):519-537
It is known that in the Minkowski sum of r polytopes in dimension d, with r<d, the number of vertices of the sum can be as high as the product of the number of vertices in each summand. However, the
number of vertices for sums of more polytopes was unknown so far. 相似文献
118.
The analysis of changes in the vibrational spectrum of infrared active molecules adsorbed on a ionic surface containing point or extended defects can be an efficient method to determine the nature and density of surface defects. We study the infrared response of ammonia molecules deposited on a ionic surface of MgO containing charge vacancies and dipolar defects in various concentrations and distributions and show significant changes assigned to the defects signature. A Monte Carlo approach is used to randomly deposit the probe molecules on the surface displaying random or regularly arranged defects at low temperature. 相似文献
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