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Chiral separation

Enrique Javier Carrasco-Correa, Ernesto Francisco Simó-Alfonso, Guillermo Ramis-Ramos, Jose Manuel Herrero Martinez
This review article is primarily focused on the state-of-the-art of enantioseparations on organic monolithic materials. The article gives an overview of the chiral stationary phases and its application in capillary electrochromatography (CEC), and capillary- and nano-liquid chromatography (cLC and nLC). Since thousands of publications have been emerged from 2000's and citing all these papers would extend the scope of this review, in this review, recent developments (from 2006 to 2016) last 10 years will be mentioned...
January 11, 2017: Current Medicinal Chemistry
Md Fokhrul Islam, Suraj Adhikari, Man-Jeong Paik, Wonjae Lee
The liquid chromatographic enantiomer separation of various chiral acids as 1-naphthylamides was performed using several chiral stationary phases (CSPs). The CSPs used in this study were six covalently bonded and four coated type CSPs derived from amylose and cellulose derivatives as chiral selectors. The degree of enantioseparation is affected by the structure of chiral acids and the CSPs used, which have different chiral selectors and types of immobilization. For the enantiomer resolution of chiral acids as 1-naphthylamide derivatives, the performance of the coated type Lux Cellulose-1 was superior to those of the other CSPs, except for 2-aryloxypropionic acid derivatives...
January 10, 2017: Archives of Pharmacal Research
Bilu Liu, Fanqi Wu, Hui Gui, Ming Zheng, Chongwu Zhou
Preparation of chirality-defined single-wall carbon nanotubes (SWCNTs) is the top challenge in the nanotube field. In recent years, great progress has been made toward preparing single-chirality SWCNTs through both direct controlled synthesis and postsynthesis separation approaches. Accordingly, the uses of single-chirality-dominated SWCNTs for various applications have emerged as a new front in nanotube research. In this Review, we review recent progress made in the chirality-controlled synthesis of SWCNTs, including metal-catalyst-free SWCNT cloning by vapor-phase epitaxy elongation of purified single-chirality nanotube seeds, chirality-specific growth of SWCNTs on bimetallic solid alloy catalysts, chirality-controlled synthesis of SWCNTs using bottom-up synthetic strategy from carbonaceous molecular end-cap precursors, etc...
January 10, 2017: ACS Nano
Cristiana Margarita, Pher G Andersson
The catalytic enantioselective hydrogenation of prochiral olefins is a key reaction in asymmetric synthesis. Its relevance applies to both industry and academia as an inherently direct and sustainable strategy to induce chirality. Here we briefly recount the early breakthroughs concerning the asymmetric hydrogenation of largely unfunctionalized olefins, from the first reports to the advent of chiral Crabtree-like catalysts. The mechanism and its implications on the enantioselectivity are shortly discussed. The main focus of this Perspective lies on the more recent advances in the field, such as the latest developed classes of ligands and the opportunity to employ more earth-abundant metals...
January 7, 2017: Journal of the American Chemical Society
Jennifer A Weiß, Kian Kadkhodaei, Martin G Schmid
Amphetamine and its derivatives gained high popularity on the illegal drug market. In the last few years, a lot of new psychoactive compounds structurally related to amphetamine, such as 4-fluoroamphetamine and 4-fluoromethamphetamine swamped the drug market. They were designed to circumvent prohibition of amphetamine and N-methylamphetamine and are distributed via the Internet. Often, a halogen atom is introduced into the phenyl ring of amphetamine to turn the illegal amphetamine legal. Since amphetamines possess a chiral centre, two enantiomers are available, which might differ in activity...
January 2017: Science & Justice: Journal of the Forensic Science Society
D Camacho-Muñoz, B Kasprzyk-Hordern
This paper presents a multi-residue method for direct enantioselective separation of chiral pharmacologically active compounds in environmental matrices. The method is based on chiral liquid chromatography and tandem mass spectrometry detection. Simultaneous chiral discrimination was achieved with a macrocyclic glycopeptide-based column with antibiotic teicoplanin as a chiral selector working under reverse phase mode. For the first time, enantioresolution was reported for metabolites of ibuprofen: carboxyibuprofen and 2-hydroxyibuprofen with this chiral stationary phase...
January 6, 2017: Journal of Mass Spectrometry: JMS
M Defurne, M Mazouz, Z Ahmed, H Albataineh, K Allada, K A Aniol, V Bellini, M Benali, W Boeglin, P Bertin, M Brossard, A Camsonne, M Canan, S Chandavar, C Chen, J-P Chen, C W de Jager, R de Leo, C Desnault, A Deur, L El Fassi, R Ent, D Flay, M Friend, E Fuchey, S Frullani, F Garibaldi, D Gaskell, A Giusa, O Glamazdin, S Golge, J Gomez, O Hansen, D Higinbotham, T Holmstrom, T Horn, J Huang, M Huang, G M Huber, C E Hyde, S Iqbal, F Itard, Ho Kang, Hy Kang, A Kelleher, C Keppel, S Koirala, I Korover, J J LeRose, R Lindgren, E Long, M Magne, J Mammei, D J Margaziotis, P Markowitz, A Martí Jiménez-Argüello, F Meddi, D Meekins, R Michaels, M Mihovilovic, N Muangma, C Muñoz Camacho, P Nadel-Turonski, N Nuruzzaman, R Paremuzyan, A Puckett, V Punjabi, Y Qiang, A Rakhman, M N H Rashad, S Riordan, J Roche, G Russo, F Sabatié, K Saenboonruang, A Saha, B Sawatzky, L Selvy, A Shahinyan, S Sirca, P Solvignon, M L Sperduto, R Subedi, V Sulkosky, C Sutera, W A Tobias, G M Urciuoli, D Wang, B Wojtsekhowski, H Yao, Z Ye, L Zana, X Zhan, J Zhang, B Zhao, Z Zhao, X Zheng, P Zhu
We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}...
December 23, 2016: Physical Review Letters
Martha Knight, Rodrigo Lazo-Portugal, Saeyoung Nate Ahn, Steingrimur Stefansson
Over the last decade man-made carbon nanostructures have shown great promise in electronic applications, but they are produced as very heterogeneous mixtures with different properties so the achievement of a significant commercial application has been elusive. The dimensions of single-wall carbon nanotubes are generally a nanometer wide, up to hundreds of microns long and the carbon nanotubes have anisotropic structures. They are processed to have shorter lengths but they need to be sorted by diameter and chirality...
December 24, 2016: Journal of Chromatography. A
Lia Bezhitashvili, Anna Bardavelidze, Teona Ordjonikidze, Lali Chankvetadze, Mike Chity, Tivadar Farkas, Bezhan Chankvetadze
Our earlier studies on the preparation of chiral stationary phases (CSP) based on superficially porous (or core-shell) silica (SPS) particles for the separation of enantiomers in HPLC have provided proof to the advantages of such sorbents. In particular, higher enantioselectivity was observed with the columns packed with superficially porous CSP compared to the columns packed with fully-porous (FP) silica-based CSPs at comparable content of chiral selector (polysaccharide derivative) in CSP. Also, less dependence of plate height on mobile phase flow rate and higher plate numbers and resolution calculated per unit time (i...
December 29, 2016: Journal of Chromatography. A
Iza Matarashvili, Darejan Ghughunishvili, Lali Chankvetadze, Nino Takaishvili, Tamar Khatiashvili, Maia Tsintsadze, Tivadar Farkas, Bezhan Chankvetadze
When polysaccharide-based chiral columns are used in combination with aqueous-organic mobile phases for the separation of enantiomers in high-performance liquid chromatography the separation mode is commonly called "reversed-phase" in analogy to achiral separations. In several earlier and recent studies on neutral and basic chiral analytes it was shown by our and other groups that due to multiple type of interactions involved in selector-selectand binding and enantioselective recognition with polysaccharide derivatives, the above mentioned separation system may not always behave like a reversed-phase system...
December 22, 2016: Journal of Chromatography. A
Tohru Shibata, Satoshi Shinkura, Atsushi Ohnishi, Kazuyoshi Ueda
Chromatographic separation of several sets of aromatic position isomers on three cellulose- and one amylose-based chiral stationary phases was performed to evaluate the potential of a polysaccharide-based chiral stationary phase (CSP) in the separation of isomeric or closely similar molecules, and to understand the interaction mechanism of this type of CSP with analytes. Their ability of molecular recognition was quite outstanding, but the selection rule was particular to each polysaccharide derivative. In the series of analytes, cellulose tris(4-methylbenzoate) and tris(3,5-dimethylphenylcarbamate) exhibited a contrasting selection rule, and the recognition mechanism was considered based on the computer-simulation of the former polymer...
December 28, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Hai-Bing Liao, Guang-Hui Huang, Mei-Hua Yu, Chun Lei, Ai-Jun Hou
Chemical investigation on the aerial parts of Rhododendron capitatum resulted in the discovery of five enantiomeric pairs of new meroterpenoids, (+)-/(-)-rhodonoids C (1a and 1b), E (3a and 3b), F (4a and 4b), and (-)-/(+)-rhodonoids D (2a and 2b) and G (5a and 5b). These enantiomeric pairs existed as partial racemates in a plant and were obtained by chiral HPLC separation. Their structures with absolute configurations were assigned by spectroscopic data, single-crystal X-ray diffraction, and ECD analysis. Compounds 1a and 1b are the first pair of meromonoterpenes incorporating an unprecedented 6/6/6/5 ring system, and 1a showed antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro...
January 12, 2017: Journal of Organic Chemistry
Magdalena Taschwer, Jörg Grascher, Martin G Schmid
Since the last decade, the hype of the recreational use of novel psychoactive drugs is still on its top in entire Europe. Every year, new derivatives enter the drug market and enlarge the broad spectrum of misused drugs. Many of these compounds contain a stereogenic centre and therefore two enantiomers exist. It is obvious that the pharmacological potency of the isomers differ as it is already known from various pharmaceutical ingredients. Therefore, the development of analytical methods for the chiral separation of new psychoactive substances is of great medical and forensic interest...
October 20, 2016: Forensic Science International
Nejal M Bhatt, Vijay D Chavada, Mallika Sanyal, Pranav S Shrivastav
A simple and efficient high-performance thin-layer chromatographic method was developed for chiral separation of rac-bupropion (BUP) and its active metabolite rac-hydroxybupropion (HBUP). Design of experiment (DoE)-based optimization was adopted instead of a conventional trial-and-error approach. The Box-Behnken design surface response model was used and the operating variables were optimized based on 17 trials design. The optimized method involved impregnation of chiral reagent, L(+)-tartaric acid, in the stationary phase with simultaneous addition in the mobile phase, which consisted of acetonitrile : methanol : dichloromethane : 0...
December 28, 2016: Chirality
Simone K Schmidt, Georg Höfner, Klaus T Wanner
For the enantiopure synthesis of novel chiral GABA uptake inhibitors, nipecotic acid (1) is an important key precursor. To characterize accurately the pharmacological activity of these interesting target compounds, the determination of the correct enantiomeric purity of nipecotic acid as the starting material is indispensable. In this report, a sensitive high-performance liquid chromatography (HPLC) based method for the separation and quantitation of both enantiomers of nipecotic acid as 1-(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl) derivatives (5) on a Chiralpak ID-3 column (Daicel, Illkirch, France) was established...
December 26, 2016: Chirality
Qi-Yi Zhang
Chiral objects in shear flow experience a chirality-specific lift force. Shear flows past helices in a low Reynolds number regime were studied using slender-body theory. The chirality-specific lift forces in the vorticity direction experienced by helices are dominated by a set of helix geometry parameters: helix radius, pitch length, number of turns, and helix phase angle. Its analytical formula is given. The chirality-specific forces are the physical reasons for the chiral separation of helices in shear flow...
December 26, 2016: Chirality
Clara Shionyu-Mitsuyama, Atsushi Hijikata, Toshiyuki Tsuji, Tsuyoshi Shirai
The fast heuristic graph match algorithm for small molecules, COMPLIG, was improved by adding a structural superposition process to verify the atom-atom matching. The modified method was used to classify the small molecule ligands in the Protein Data Bank (PDB) by their three-dimensional structures, and 16,660 types of ligands in the PDB were classified into 7561 clusters. In contrast, a classification by a previous method (without structure superposition) generated 3371 clusters from the same ligand set. The characteristic feature in the current classification system is the increased number of singleton clusters, which contained only one ligand molecule in a cluster...
December 23, 2016: Journal of Structural and Functional Genomics
M H Alizadeh, B M Reinhard
Transverse spin angular momentum (SAM) of light and associated transverse chiral optical forces have received tremendous attention recently, as the latter may lead to an optical separation of chiral biomolecules. In this context, the relative magnitude of chiral and non-chiral forces is a challenge when implementing chiral separation schemes. In this work we have demonstrated that, by spatially separating the maxima of transverse spin density from the gradient of field intensity, it is possible to dominate chiral-specific components of the force over non-chiral ones...
October 15, 2016: Optics Letters
Jing Gao, Han Qu, Chuntao Zhang, Weijia Li, Peng Wang, Zhiqiang Zhou
The enantiomeric separation of the enantiomers of three phenylpyrazole pesticides (fipronil, flufiprole, ethiprole) and two fipronil metabolites (amide-fipronil and acid-fipronil) were investigated by high-performance liquid chromatography (HPLC) with a CHIRALPAK(®) IB chiral column. The mobile phase was n-hexane or petroleum ether with 2-propanol or ethanol as modifier at a flow rate of 1.0 mL/min. The influences of mobile phase composition and column temperature between 15 and 35°C on the separations were studied...
December 21, 2016: Chirality
Xiaoyu Hu, Xin Guo, Shuo Sun, Bolin Zhu, Jia Yu, Xingjie Guo
High-performance liquid chromatography (HPLC) is a powerful method in the area of chiral separation. In this study, a method of HPLC using carboxymethyl-β-cyclodextrin (CM-β-CD) as chiral selector was developed for enantioseparation of nine indanone and tetralone derivatives. The separation was performed on a conventional C18 column. The optimal mobile phase was a mixture of methanol and 0.05 mol/L phosphate buffer at pH 1.8 (55:45, v/v) containing 22.9 mmol/L CM-β-CD. Under such conditions, the resolutions of all analytes were over 1...
December 19, 2016: Chirality
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