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Chiral separation

Takahiro Doi, Akiko Asada, Akihiro Takeda, Takaomi Tagami, Munehiro Katagi, Hiroe Kamata, Yoshiyuki Sawabe
Synthetic cannabinoids, recently used as alternatives to Cannabis sativa, are among the most frequently abused drugs. Identified in 2014, the synthetic cannabinoids N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide (5F-AB-PINACA) and methyl [1-(5-fluoropentyl)-1H-indazole-3-carbonyl]-valinate (5F-AMB) are carboxamides composed of 1-(5-fluoropentyl)-1H-indazole-3-carboxylic acid and valine amide/methyl ester. Because of their composition, these molecules have pairs of enantiomers derived from the chiral center of their amino acid structures...
October 19, 2016: Journal of Chromatography. A
Jesús Marín-Sáez, Roberto Romero-González, Antonia Garrido Frenich
A new method has been developed for the enantioselective separation of (-) and (+) hyoscyamine in Solanaceaes seeds and contaminated buckwheat. Chromatographic separation was optimized, evaluating two chiral columns, Chirobiotic V and Chiralpal-AY3. Better resolution was obtained using a Chiralpak-AY3 column, utilizing as mobile phase ethanol (0.1% diethanolamine). An extraction procedure based on a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) was applied, using water and acetonitrile containing 1% of acetic acid, and a clean-up step utilizing primary secondary amine (PSA) and graphitized carbon black (GCB) as sorbents...
October 19, 2016: Journal of Chromatography. A
Shanshan Wang, Chao Han, Sisi Wang, Lijuan Bai, Shanshan Li, Jianguang Luo, Lingyi Kong
Cu(II) complexed amino acid ionic liquid, Cu(II)-[1-butyl-3-methylimidazolium][L-Pro] (Cu(II)-[BMIm][L-Pro]), was successfully adopted as chiral ligand to improve the enantioseparation efficiency in high speed counter-current chromatography (HSCCC). For the enantioseparation of intractable naringenin (NRG) racemic mixtures, Cu(II)-[BMIm][L-Pro] coupled with hydroxypropyl-β-cyclodextrin (HP-β-CD) was successfully applied as dual chiral selectors in HSCCC. The influence of important parameters, including the concentration of the chiral selectors, the pH value, and the temperature were investigated...
October 14, 2016: Journal of Chromatography. A
Salvatore Fanali
This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers' separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc...
October 14, 2016: Journal of Chromatography. A
Lu Wang, Xiang-Yong Liang, Li-Sheng Ding, Sheng Zhang, Bang-Jing Li
A new type of chiral magnetic nano-particles was prepared via covalently linked magnetic nano-particles (Fe3O4) and heptakis (6-O-triisopropylsilyl)-β-cyclodextrin (6-TIPS-β-CD). The resulting selectors (TIPS-β-CD-MNPs) combined the high magnetic property Fe3O4 and efficient chiral recognition ability of 6-TIPS-β-CD. The enantioselectivity of TIPS-β-CD-MNPs towards 1-(1-naphthyl) ethylamine was six times higher than that of parent β-CD modified Fe3O4 particles.
October 20, 2016: Chemistry, An Asian Journal
Jingqian Xie, Lu Zhao, Kai Liu, Fangjie Guo, Weiping Liu
The chirality of herbicides has been the focus of research. However, there is little information on the enantioseparation of amide herbicides with different chiral elements. In this study, the need for different chiral stationary phases (CSPs), mobile phases, temperatures and flow rates for the separation of napropamide, acetochlor and propisochlor was discussed in detail and compared to metolachlor. Resolution of C-chiral enantiomers was easier than that of axial-chiral enantiomers. Metolachlor and acetochlor could achieve baseline separation only on AY-H and AS-H columns, respectively...
October 13, 2016: Journal of Chromatography. A
Federica Lanni, Andrea Carotti, Roccaldo Sardella, Antonio Macchiarulo, Lucia Pucciarini, Benedetto Natalini
In the last few decades, there has been a significant increase in the development of chiral compounds. Thus, access to enantiomerically pure compounds is currently a major focus of pharmaceutical research and, in particular, chiral HPLC separations have gained great importance for semi-preparative and industrial isolation of enantiopure compounds. Chemoinformatic procedures as well as molecular modelling and quantum chemistry techniques can be successfully applied to address chirality related problems especially when enantiomerically pure reference standards are missing...
October 18, 2016: Mini Reviews in Medicinal Chemistry
Dennis G Hall, Taras Rybak, Tristan Verdelet
Multicomponent reactions (MCR), transformations employing three or more simple substrates in a single and highly atom-economical operation, are very attractive in both natural product synthesis and diversity-oriented synthesis of druglike molecules. Several popular multicomponent reactions were designed by combining two well-established individual reactions that utilize mutually compatible substrates. In this regard, it is not surprising that the merging of two reactions deemed as workhorses of stereoselective synthesis, the Diels-Alder cycloaddition and carbonyl allylboration, would produce a powerful and highly versatile tandem MCR process...
October 18, 2016: Accounts of Chemical Research
Xian-Hua Wang, Qian Dong, Ling-Ling Ying, Shuai-Shuai Chi, Yao-Han Lan, Yan-Ping Huang, Zhao-Sheng Liu
In this study, a new molecularly imprinted polymer chiral stationary phase (MIP-CSP) was prepared utilizing molecular crowding agent for improvement the selective separation ability. S-amlodipine (S-AML), methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA), and polymethyl methacrylate (PMMA) were selected as template, functional monomer, cross-linker, and molecular crowding agent, respectively. The composition of formulas for MIP-CSP was optimized, and the permeability and structural feature of resultant MIP-CSP were characterized...
October 15, 2016: Analytical and Bioanalytical Chemistry
Niklas Müller, Sören Schlichting, Sayantan Sharma
We present a first-principles study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian SU(N_{c}) and Abelian U(1) gauge fields. Investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the chiral magnetic and chiral separation effect leads to the formation of a propagating wave. We further analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on the amount of explicit chiral symmetry breaking due to finite quark masses...
September 30, 2016: Physical Review Letters
F Arnold, M Naumann, S-C Wu, Y Sun, M Schmidt, H Borrmann, C Felser, B Yan, E Hassinger
Tantalum arsenide is a member of the noncentrosymmetric monopnictides, which are putative Weyl semimetals. In these materials, three-dimensional chiral massless quasiparticles, the so-called Weyl fermions, are predicted to induce novel quantum mechanical phenomena, such as the chiral anomaly and topological surface states. However, their chirality is only well defined if the Fermi level is close enough to the Weyl points that separate Fermi surface pockets of opposite chirality exist. In this Letter, we present the bulk Fermi surface topology of high quality single crystals of TaAs, as determined by angle-dependent Shubnikov-de Haas and de Haas-van Alphen measurements combined with ab initio band-structure calculations...
September 30, 2016: Physical Review Letters
Sunghan Ro, Juyeon Yi, Yong Woon Kim
Separation of enantiomers by flows is a promising chiral resolution method using cost-effective microfluidics. Notwithstanding a number of experimental and numerical studies, a fundamental understanding still remains elusive, and an important question as to whether it is possible to specify common physical properties of flows that induce separation has not been addressed. Here, we study the separation of rigid chiral objects of an arbitrary shape induced by a linear flow field at low Reynolds numbers. Based on a symmetry property under parity inversion, we show that the rate-of-strain field is essential to drift the objects in opposite directions according to chirality...
October 14, 2016: Scientific Reports
H Grajek, Z Witkiewicz, M Purchała, W Drzewiński
The most correct analysis of the compositions of diverse analytes mixtures is significant for analytical studies in different fields; however, many prevalent analytes cannot be identified employing traditional partition gas chromatographic methods. Thus, the increasing requirements on analytes of isomeric compounds and the problems encountered in their separation demand a study of more diverse analytical systems which are characterised by higher selectivity. Therefore, the selectivity and polarities of various liquid crystals (rod-like, banana-shape, biforked, oxygen, sulphur, nitrogen, and metal containing molecules, Schiff-base, and polymeric dendrimers) employed as liquid crystalline stationary phases (LCSPs) have been discussed from both points of views, namely, their analytical applications and thermodynamic characteristics of infinitely diluted probes with different acceptor-donor properties...
2016: Chromatographia
Xin Wang, Alexandros Lamprou, Frantisek Svec, Yu Bai, Huwei Liu
A new approach to the preparation of enantioselective porous polymer monolithic columns with incorporated chiral metal-organic framework for nano-liquid chromatography has been developed. While no enantioseparation was achieved with monolithic poly(4-vinylpyridine-co-ethylene dimethacrylate) column, excellent separations of both enantiomers of (±)-methyl phenyl sulfoxide were achieved with its counterpart prepared after admixing the metal-organic framework [Zn2 (benzene dicarboxylate)(l-lactic acid)(dmf)](DMF), which is synthesized from zinc nitrate, l-lactic acid, and benzene dicarboxylic acid in the polymerization mixture...
October 12, 2016: Journal of Separation Science
Martin Walker, Mark R Wilson
Dissipative particle dynamics (DPD) simulations are used to model the aqueous self-assembly of three variants of the non-ionic triphenylene-based chromonic mesogen, TP6EO2M. In the variants studied, one to three of the six methoxy poly(ethylene glycol) chains of TP6EO2M are replaced by short hydrophobic-lipophobic chains, causing a remarkable change in the structure of the mesophases formed. In the 100 wt% limit, corresponding to pure thermotropic phases, complex columnar phases arise, in which the underlying hexagonal packing is supplemented by additional order resulting from microphase separation of hydrophobic-lipophobic regions...
September 26, 2016: Soft Matter
Anton A Burkov, Yong Baek Kim
We demonstrate that topological Dirac semimetals, which possess two Dirac nodes, separated in momentum space along a rotation axis and protected by rotational symmetry, exhibit an additional quantum anomaly, distinct from the chiral anomaly. This anomaly, which we call the Z_{2} anomaly, is a consequence of the fact that the Dirac nodes in topological Dirac semimetals carry a Z_{2} topological charge. The Z_{2} anomaly refers to nonconservation of this charge in the presence of external fields due to quantum effects and has observable consequences due to its interplay with the chiral anomaly...
September 23, 2016: Physical Review Letters
Debabrata Pramanik, Prabal K Maiti
Various unique physical, chemical, mechanical and electronic properties of carbon nanotubes (CNTs) make them very useful materials for diverse potential application in many fields. Experimentally synthesized CNTs are generally found in bundle geometry with a mixture of different chiralities and present a unique challenge to separate them. In this paper we have proposed the PAMAM dendrimer to be an ideal candidate for this separation. To estimate the efficiency of the dendrimer for the dispersion of CNTs from the bundle geometry, we have calculated potential of mean forces (PMF)...
September 26, 2016: Soft Matter
Ling-Zhi Li, Xiao Liang, Xue Sun, Xiao-Li Qi, Jian Wang, Qing-Chun Zhao, Shao-Jiang Song
Two new norditerpenoids, miltiolactones A and B (1a, 1b); seven new neolignans, miltiolignanolides A-G (2a, 2b and 3a, 3b and 4a, 4b, and 5) were obtained from the root extract of Salvia miltiorrhiza. Using HPLC separation with a chiral column, compounds 1-4 were found to exist as four pairs of enantiomers. Compounds 2-5 are novel neolignans with a dibenzocycloheptatriene ring system, which form an unprecedented 6/7/6 carbon skeleton. The structures were established via extensive spectroscopic analysis, and experimental and calculated electronic circular dichroism (ECD) spectra, and compound 1 was also elucidated by X-ray diffraction experiments...
October 6, 2016: Organic & Biomolecular Chemistry
Xiaojun Wei, Takeshi Tanaka, Yohei Yomogida, Naomichi Sato, Riichiro Saito, Hiromichi Kataura
Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers...
October 5, 2016: Nature Communications
Hanna Leek, Linda Thunberg, Anna C Jonson, Kristina Öhlén, Magnus Klarqvist
A strategy for large-scale chiral resolution is illustrated by the isolation of pure enantiomer from a 5kg batch. Results from supercritical fluid chromatography will be presented and compared with normal phase liquid chromatography. Solubility of the compound in the supercritical mobile phase was shown to be the limiting factor. To circumvent this, extraction injection was used but shown not to be efficient for this compound. Finally, a method for chiral resolution by crystallization was developed and applied to give diastereomeric salt with an enantiomeric excess of 99% at a 91% yield...
September 28, 2016: Drug Discovery Today
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