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61.
In the present work, we report a comprehensive vibrational circular dichroism (VCD) spectroscopic study of a chiral crown ether which features an axial chiral 3.3'‐diphenyl‐1,1'‐binaphthyl group as chiral moiety. By comparing the experimental and calculated VCD spectra, we show that the presumably very flexible crown ether preferably adopts only one ring conformation. Conformational flexibility is observed in the 2,4‐dinitrophenyl‐diazophenol group, which was previously introduced for colorimetric detection of primary amines and amino alcohols (Cho et al., Chirality 2011;23:349–353). The VCD spectra of the host–guest complexes with phenyl glycinol (PG) and phenyl alaninol have been studied as well. Based on the spectra calculated, it is shown that the diastereomeric complexes in general can be differentiated using VCD spectroscopy. Furthermore, the experimental VCD spectra of the complexes of the host molecule with PG support the above finding. Chirality 25:294–300, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
62.
Xiao‐Peng Zhang Tao Wu Jian Liu Jin‐Cheng Zhao Cheng‐Hui Li Xiao‐Zeng You 《Chirality》2013,25(7):384-392
Two couples of enantiomeric platinum(II) complexes: Pt(L1a)Cl ( 1a ), Pt(L1b)Cl ( 1b ) and Pt(L1a)(C ≡ C ? Ph) ( 2a ), Pt(L1b)(C ≡ C ? Ph) ( 2b ) (L1a = (+)‐1,3‐di‐(2‐(4,5‐pinene)pyridyl)benzene, L1b = (?)‐1,3‐di‐(2‐(4,5‐pinene)pyridyl)benzene) were synthesized and characterized. Their absolute configurations were determined by single crystal X‐ray diffraction and further verified by circular dichroism (CD) spectra (including electronic circular dichroism [ECD] and vibrational circular dichroism [VCD]). These complexes show interesting mechanoluminescence and/or vapoluminescence due to crystalline‐to‐amorphous transformation. The crystalline solids, grinding‐induced amorphous powders, and vapor‐induced amorphous powders of complexes 2a and 2b were comparatively investigated by solid‐state ECD and VCD spectra. The transformation from crystalline solids to amorphous powders was accompanied by significant variances of the spectral feature in both ECD and VCD spectra. Chirality 25:384–392, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
63.
The existence of enantiomer‐enriched mixtures of chiral pesticides in the environment is overwhelmingly positive. However, interactions between enantiomers have not been considered so far in risk assessments. Here, we chose three organophosphorus pesticides as representative chiral pesticides to investigate the possible interaction mode between each pair of enantiomers both in in vivo and in vitro. Data show that the enantiomers of methamidophos and profenofos have a simple additive effect, <zaq;1> whereas fensulfothion acts as an antagonist in AChE‐inhibition model. In contrast, enantiomers of methamidophos and fensulfothion had an additive effect in an acute toxicity test against Daphnia magna. A synergistic effect was observed in the joint toxicity of the profenofos enantiomers. The ability for enantiospecific biodegradation in the in vivo model contributed to the different interaction observed between the in vitro and in vivo models. Moreover, binding affinities were suspected as another reason for the different mode of action of mixture enantiomers. Our study recommends using a joint research model to treat chiral compounds in the real environment. Chirality 25:787–792, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
64.
Wes Schafer Tilak Chandrasekaran Zainab Pirzada Chaowei Zhang Xiaoyi Gong Mirlinda Biba Erik L. Regalado Christopher J. Welch 《Chirality》2013,25(11):799-804
In this study we describe the evaluation of a recently developed supercritical fluid chromatography (SFC) instrument for automated chiral SFC method development. The greatly improved gradient dwell volume and liquid flow control of the new instrument in combination with the use of shorter columns containing smaller stationary phase particles affords chiral SFC method development that is faster and more universal than previous systems. Chirality 25:799–804, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
65.
Chiral sulfoxides/N‐oxides (R)‐ 1 and (R,R)‐ 2 are effective chiral promoters in the enantioselective allylation of α‐keto ester N‐benzoylhydrazone derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g to generate the corresponding N‐benzoylhydrazine derivatives 4a , 4b , 4c , 4d , 4e , 4f , 4g , with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a , 4b were subsequently treated with SmI2, and the resulting amino esters 5a , 5b with LiOH to obtain quaternary α‐substituted α‐allyl α‐amino acids 6a , 6b , whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. Chirality 25:529–540, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
66.
ZhiLi Fang WenCui Su WeiGuang Zhang Yan Xu YaJin Xiong MiaoLi Luo Jun Fan Xia Yin 《Journal of molecular recognition : JMR》2013,26(4):161-164
The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S‐1‐(4‐methoxyphenyl)ethylamine, and R,S‐1‐(3‐methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet‐visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
67.
《Bioscience, biotechnology, and biochemistry》2013,77(9):2418-2422
(RS)-β-Ionol and (RS)-2-methyl-4-octanol were resolved by using (S)-2-methoxy-2-(1-naphthyl)propanoic acid [(S)-MαNP acid]. The specific stereochemistry of each MαNP ester was elucidated by 2D NMR analyses, and shielding by the 1-naphthyl group was observed in both the 1H- and 13C-NMR spectra. Solvolysis of the individual (S)-MαNP esters gave four single-enantiomer alcohols. The normal-phase HPLC elution order of each MαNP ester is also discussed. 相似文献
68.
Sang-Woo Han 《Bioscience, biotechnology, and biochemistry》2013,77(10):1788-1790
Removal of a side product to overcome unfavorable equilibrium is a prerequisite for the asymmetric amination of ketones using ω-transaminase (ω-TA). Alanine has been preferred as an amino donor because its deamination product (i.e. pyruvate) is easily removable by several enzymatic methods. Here, we demonstrated that the removal of pyruvate by an innate metabolic pathway could afford equilibrium shift of the ω-TA reactions. 相似文献
69.
Intense Chiral Optical Phenomena in Racemic Polymers by Cocrystallization With Chiral Guest Molecules: A Brief Overview
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This review is devoted to the chiral optical behavior of films of racemic polymers whose chirality is induced by cocrystallization with nonracemic (also temporary) guest molecules. We provide examples of macromolecular amplification of chirality, produced by molecular and supramolecular mechanisms, on industrially relevant polymers like poly(2,6‐dimethyl‐1,4‐phenylene)oxide (PPO) and syndiotactic polystyrene (s‐PS). Chirality 28:29–38, 2016. © 2015 Wiley Periodicals, Inc. 相似文献
70.
Enantiomerization of Allylic Trifluoromethyl Sulfoxides Studied by HPLC Analysis and DFT Calculations
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Laetitia Bailly Emilie Petit Mayaka Maeno Norio Shibata Oliver Trapp Pascal Cardinael Isabelle Chataigner Dominique Cahard 《Chirality》2016,28(2):136-142
Enantiomerization of allylic trifluoromethyl sulfoxides occurs spontaneously at room temperature through the corresponding allylic trifluoromethanesulfenates via a [2,3]‐sigmatropic rearrangement. Dynamic enantioselective high‐performance liquid chromatography (HPLC) analysis revealed the stereodynamics of these sulfoxides ranging from chromatographic resolution to peak coalescence at temperatures between 5 and 53 °C. The rate constant of enantiomerization and activation parameters were determined and compared with Density Functional Theory (DFT) calculations. Chirality 28:136–142, 2016. © 2015 Wiley Periodicals, Inc. 相似文献