排序方式: 共有105条查询结果,搜索用时 31 毫秒
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Tianxiang Chen Bolong Huang Sarah Day Chiu Chung Tang Shik Chi Edman Tsang Kwok-yin Wong Tsz Woon Benedict Lo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1109-1113
Reported here is the first crystallographic observation of stereospecific bindings of l - and d -lysine (Lys) in achiral MFI zeolites. The MFI structure offers inherent geometric and internal confinement effects for the enantiomeric difference in l - and d -Lys adsorption. Notable differences have been observed by circular dichroism (CD) spectroscopy and thermogravimetric analysis (TGA). Distinct l - and d -Lys adsorption behaviours on the H-ZSM-5 framework have been revealed by the Rietveld refinement of high-resolution synchrotron X-ray powder diffraction (SXRD) data and the density-functional theory (DFT) calculations. Despite demonstrating the approach for l - and d -Lys over MFI zeolites at an atomistic resolution, the differential adsorption study sheds light on the rational engineering of molecular interaction(s) with achiral microporous materials for chiral separation purposes. 相似文献
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Chiral Conflict as a Method to Create Stimuli‐Responsive Materials Based on Dynamic Helical Polymers
Mohammad Alzubi Sandra Arias Rafael Rodríguez Emilio Quio Ricardo Riguera Flix Freire 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13499-13503
A new multi‐sensor material based on helical copolymers showing the chiral conflict effect have been prepared. It can successfully detect and identify diverse metal cations in solution. The design of this material has taken into account not only the opposite helical senses induced by the two chiral monomers in the copolymer, but also their dynamic behavior. The induced helical sense can thus be enhanced, diminished, or inverted by interaction with different stimuli (that is, metal ions). Thus, depending on both the copolymer compositions (such as monomer ratios and absolute configurations) and the nature of the metal ion, the response of these dynamic helical copolymers to adopt a single‐handed P or M helix is unique, making it possible not only to detect their presence, but also to identify them individually. New multi‐sensors materials based and inspired on this effect should arise in the future choosing appropriate monomers and stimuli. 相似文献
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Joseph Y. M. Chan Takahiro Kawata Nagao Kobayashi Dennis K. P. Ng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2294-2299
Condensation of 1,8‐diamino‐3,6‐dichlorocarbazole with a series of disubstituted 1,3‐diiminoisoindolines, followed by treatment with BF3?OEt2 led to the formation of the corresponding core‐expanded boron(III) subphthalocyanine analogues. These air‐stable π‐conjugated boron(III) carbazosubphthalocyanines possess two boron‐containing seven‐membered‐ring units and a 16 π‐electron skeleton, and represent the first examples of antiaromatic boron(III) subphthalocyanine analogues as supported by spectroscopic and theoretical studies. The molecular structure of one of these compounds was unambiguously determined by single‐crystal X‐ray diffraction analysis. In contrast to typical boron(III) subphthalocyanines, which adopt a cone‐shaped structure, the π skeleton of this compound is almost planar. 相似文献
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Farinaz Mortaheb Katrin Oberhofer Johann Riemensberger Florian Ristow Reinhard Kienberger Ulrich Heiz Hristo Iglev Aras Kartouzian 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15832-15836
The interest in enantioseparation and enantiopurification of chiral molecules has been drastically increasing over the past decades, since these are important steps in various disciplines such as pharmaceutical industry, asymmetric catalysis, and chiral sensing. By exposing racemic samples of BINOL (1,1′‐bi‐2‐naphthol) coated onto achiral glass substrates to circularly polarized light, we unambiguously demonstrate that by controlling the handedness of circularly polarized light, preferential desorption of enantiomers can be achieved. There are currently no mechanisms known that would describe this phenomenon. Our observation together with a simplified phenomenological model suggests that the process of laser desorption needs to be further developed and the contribution of quantum mechanical processes should be revisited to account for these data. Asymmetric laser desorption provides us with a contamination‐free technique for the enantioenrichment of chiral compounds. 相似文献
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