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Chiral separation

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https://www.readbyqxmd.com/read/28732286/development-of-liquid-chromatographic-methods-for-enantioseparation-and-sensitive-detection-of-%C3%AE-adrenolytics-%C3%AE-2-agonists-in-human-plasma-using-a-single-enantiomer-reagent
#1
Poonam Malik, Ravi Bhushan
Enantioseparation of four commonly used β-adrenolytics (bisoprolol, salbutamol, and carvedilol, marketed as racemic mixtures) has been achieved by both TLC and RPHPLC via an indirect approach. A new chiral reagent, (S)-naproxen benzotriazole ester, was synthesized and it was characterized by UV, IR, (1)HNMR, elemental analysis and polarimetry. It was used to synthesize diastereomeric derivatives of the three β-adrenolytics under microwave irradiation. TLC separation of diastereomeric derivatives was achieved which were then isolated by preparative approach; these were characterized and were used as standard reference for determining absolute configuration of diastereomeric derivatives and for establishing validated HPLC method for enantioseparation and sensitive detection of the three β-adrenolytics in human plasma...
July 14, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28730706/chromatographic-profiles-of-tryptophan-and-kynurenine-enantiomers-derivatized-with-s-4-3-isothiocyanatopyrrolidin-1-yl-7-n-n-dimethylaminosulfonyl-2-1-3-benzoxadiazole-using-lc-ms-ms-on-a-triazole-bonded-column
#2
Hideaki Iizuka, Takahiro Harashima, Shuhei Takahashi, Ryosuke Kuwabara, Yoko Naito, Tatsuya Sakamoto, Mayu Onozato, Hideaki Ichiba, Takeshi Fukushima
d- and l-Tryptophan (Trp) and d- and l-kynurenine (KYN) were derivatized with a chiral reagent, (S)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole (DBD-PyNCS), and were separated enantiomerically by high-performance liquid chromatography (HPLC) equipped with a triazole-bonded column (Cosmosil HILIC) using tandem mass spectrometric (MS/MS) detection. Effects of column temperature, salt (HCO2 NH4 ) concentration, and pH of the mobile phase in the enantiomeric separation, followed by MS detection of (S)-DBD-PyNCS-d,l-Trp and -d,l-KYN, were investigated...
July 21, 2017: Chirality
https://www.readbyqxmd.com/read/28726829/experimental-signatures-of-the-mixed-axial-gravitational-anomaly-in-the-weyl-semimetal-nbp
#3
Johannes Gooth, Anna C Niemann, Tobias Meng, Adolfo G Grushin, Karl Landsteiner, Bernd Gotsmann, Fabian Menges, Marcus Schmidt, Chandra Shekhar, Vicky Süß, Ruben Hühne, Bernd Rellinghaus, Claudia Felser, Binghai Yan, Kornelius Nielsch
The conservation laws, such as those of charge, energy and momentum, have a central role in physics. In some special cases, classical conservation laws are broken at the quantum level by quantum fluctuations, in which case the theory is said to have quantum anomalies. One of the most prominent examples is the chiral anomaly, which involves massless chiral fermions. These particles have their spin, or internal angular momentum, aligned either parallel or antiparallel with their linear momentum, labelled as left and right chirality, respectively...
July 19, 2017: Nature
https://www.readbyqxmd.com/read/28719814/enantiomeric-separation-of-seven-%C3%AE-agonists-by-nace-study-of-chiral-selectivity-with-diacetone-d-mannitol-boric-acid-complex
#4
Lili Lv, Lijuan Wang, Jun Li, Yajun Jiao, Shengnan Gao, Jiachang Wang, Hongyuan Yan
A rapid and effective nonaqueous capillary electrophoresis (NACE)-ultraviolet (UV) method was developed for the enantiomeric separation of seven β-agonists. Diacetone-d-mannitol-boric acid complex was used as a new chiral selector. It was in situ synthesized by the reaction of diacetone-d-mannitol and boric acid in methanol medium containing triethylamine. The effects of diacetone-d-mannitol, boric acid, and triethylamine concentrations on the enantioseparation were carefully investigated. Under the optimized conditions, baseline enantioseparation could be obtained for six of the tested β-agonists within 12min...
July 8, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28718832/application-of-carbon-nanotubes-in-chiral-and-achiral-separations-of-pharmaceuticals-biologics-and-chemicals
#5
REVIEW
Ayman L Hemasa, Nenad Naumovski, William A Maher, Ashraf Ghanem
Carbon nanotubes (CNTs) possess unique mechanical, physical, electrical and absorbability properties coupled with their nanometer dimensional scale that renders them extremely valuable for applications in many fields including nanotechnology and chromatographic separation. The aim of this review is to provide an updated overview about the applications of CNTs in chiral and achiral separations of pharmaceuticals, biologics and chemicals. Chiral single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) have been directly applied for the enantioseparation of pharmaceuticals and biologicals by using them as stationary or pseudostationary phases in chromatographic separation techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and gas chromatography (GC)...
July 18, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28711220/analysis-of-small-molecule-drugs-excipients-and-counter-ions-in-pharmaceuticals-by-capillary-electromigration-methods-recent-developments
#6
REVIEW
Qingfu Zhu, Gerhard K E Scriba
Capillary electromigration techniques have become important tools for the analysis of pharmaceutical drugs. The present review updates on recent developments of the analysis of small molecule drugs, excipients and counter ions dating between January 2014 and May 2017. Capillary electrophoresis (CE) continues to be a very popular method for the analysis of the active pharmaceutical ingredients and their related substances in pharmaceutical formulations, especially for the determination of the stereoisomeric purity of chiral drugs, which is evidenced by a large number of related literature reported in the reviewed period of time...
June 29, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28710844/reliable-hplc-separation-vibrational-circular-dichroism-spectra-and-absolute-configurations-of-isoborneol-enantiomers
#7
Rui-Qi Gao, Jun Fan, Qi Tan, Dong Guo, Tao Chen, Ru-Jian He, Dan Li, Hui Zhang, Wei-Guang Zhang
Resolution of chiral compounds has played an important role in the pharmaceutical field, involving detailed studies of pharmacokinetics, physiological, toxicological, and metabolic activities of enantiomers. Herein, a reliable method by high-performance liquid chromatography (HPLC) coupled with an optical rotation detector was developed to separate isoborneol enantiomers. A cellulose tris(3, 5-dimethylphenylcarbamate)-coated chiral stationary phase showed the best separation performance for isoborneol enantiomers in the normal phase among four polysaccharide chiral packings...
July 15, 2017: Chirality
https://www.readbyqxmd.com/read/28710791/origin-of-enhanced-vcd-in-amyloid-fibril-spectra-effect-of-deuteriation-and-ph
#8
Markéta Pazderková, Tomáš Pazderka, Maruda Shanmugasundaram, Rina K Dukor, Igor K Lednev, Laurence A Nafie
Supramolecular chirality of amyloid fibrils, protein aggregates related to many neurodegenerative diseases, is a remarkable property associated with fibril structure and polymorphism. Since its discovery almost 10 years ago there is still little understanding of this phenomenon, including the cause of the highly enhanced vibrational circular dichroism (VCD) intensity arising from fibril supramolecular chirality. In this study, VCD spectra, enhanced by filament supramolecular chirality, are presented for lysozyme and insulin fibrils above and below pH 2 and after deuterium exchange, above and below pD 2...
July 15, 2017: Chirality
https://www.readbyqxmd.com/read/28710781/functionalities-tuned-enantioselectivity-of-phenylcarbamate-cyclodextrin-clicked-chiral-stationary-phases-in-hplc
#9
Jian Tang, Yuzhou Lin, Bo Yang, Jie Zhou, Weihua Tang
The mixed chloro- and methyl- functionalities can greatly modulate the enantioselectivities of phenylcarbamate cyclodextrin (CD) clicked chiral stationary phases (CSPs). A comparison study is herein reported for per(4-chloro-3-methyl)phenylcarbamate and per(2-chloro-5-methyl)phenylcarbamate β-CD clicked CSPs (i.e., CCC4M3-CSP and CCC2M5-CSP). The enantioselectivity dependence on column temperature was studied in both normal-phase and reversed-phase mode high performance liquid chromatography (HPLC). The thermodynamic study revealed that the stronger intermolecular interactions can be formed between CCC4M3-CSP and chiral solutes to drive the chiral separation...
July 15, 2017: Chirality
https://www.readbyqxmd.com/read/28710415/morphogenesis-and-optoelectronic-properties-of-supramolecular-assemblies-of-chiral-perylene-diimides-in-a-binary-solvent-system
#10
Xiaobo Shang, Inho Song, Hiroyoshi Ohtsu, Jiaqi Tong, Haoke Zhang, Joon Hak Oh
Chiral supramolecular structures are attracting great attention due to their specific properties and high potential in chiral sensing and separation. Herein, supramolecular assembling behaviors of chiral perylene diimides have been systematically investigated in a mixed solution of tetrahydrofuran and water. They exhibit remarkably different morphologies and chiral aggregation behaviors depending on the mixing ratio of the solvents, i.e., the fraction of water. The morphogenesis and optoelectronic properties of chiral supramolecular structures have been thoroughly studied using a range of experimental and theoretical methods to investigate the morphological effects of chiral supramolecular assemblies on the electrical performances and photogenerated charge-carrier behaviors...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28706568/gold-i-mediated-thiourea-organocatalyst-activation-a-synergic-effect-for-asymmetric-catalysis
#11
Anabel Izaga, Raquel P Herrera, M Concepción Gimeno
Several group 11 metal complexes with chiral thiourea organocatalysts have been prepared and tested as organocatalysts. The promising results on the influence of metal-assisted thiourea organocatalysts in the asymmetric Friedel-Crafts alkylation of indole with nitrostyrene are described. Better results with the metal complexes have been achieved because of the cooperative effects between the chiral thiourea and the metal. The synergic effect between both species is higher than the effect promoted by each one separately, especially for gold(I)...
April 7, 2017: ChemCatChem
https://www.readbyqxmd.com/read/28698053/stable-c-n-axial-chirality-in-1-aryluracil-scaffold-and-differences-in-in-vitro-metabolic-clearance-between-atropisomers-of-pde4-inhibitor
#12
Futoshi Hasegawa, Kazushi Kawamura, Hiroshi Tsuchikawa, Michio Murata
We report herein the stable C-N axial chirality in a 1-phenyl-6-aminouracil scaffold owing to the presence of various functional groups at the ortho-position of the N(1)-phenyl group. Racemic 1-phenyl-6-aminouracils were first separated by chiral HPLC or converting them to the corresponding diastereomers using a chiral resolving agent. We then determined the rotational barrier of each atropisomer by a thermal racemization method and found that these compounds have rotational barriers similar to other C-N axially chiral biaryls...
June 27, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28696072/comparison-of-three-s-%C3%AE-cds-with-different-degrees-of-substitution-for-the-chiral-separation-of-12-drugs-in-capillary-electrophoresis
#13
Zhaokun Wang, Qiongwen Zhang, Linda Luo, Tiemin Sun, Xingjie Guo
Three kinds of sulfated β-cyclodextrin (S-β-CD), including a single isomer, heptakis-6-sulfato-β-cyclodextrin (HS-β-CD), degree of substitution (DS) of 7, which was synthesized in our laboratory and another two commercialized randomly substituted mixtures, a sulfated β-cyclodextrin with DS of 7 to 11, as well as a highly sulfated-β-cyclodextrin with DS of 12 to 15, were used for the enantioresolution of 12 drugs (the β-blockers, phenethylamines, and anticholinergic agents) in capillary electrophoresis...
July 11, 2017: Chirality
https://www.readbyqxmd.com/read/28693730/chiral-differentiation-of-amino-acids-through-binuclear-copper-bound-tetramers-by-ion-mobility-mass-spectrometry
#14
Xiangying Yu, Zhong-Ping Yao
In this study, travelling wave ion mobility mass spectrometry has been used to investigate chiral differentiation of common chiral amino acids, through separation of binuclear copper bound tetrameric ions formed with chiral selector tryptophan, proline, tyrosine, phenylalanine or histidine. Significant chiral recognition was observed for amino acids with aromatic rings or long and active side chains, with peak-to-peak resolutions up to 1.826. Tryptophan and histidine offered better enantioselectivity, compared to other chiral selectors...
August 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28692891/degradation-studies-of-quizalofop-p-and-related-compounds-in-soils-using-liquid-chromatography-coupled-to-low-and-high-resolution-mass-analyzers
#15
Rosalía López-Ruiz, Roberto Romero-González, José Luis Martínez Vidal, Manuel Fernández-Pérez, Antonia Garrido Frenich
A comprehensive degradation study of quizalofop-p, quizalofop-p-ethyl, quizalofop-p-tefuryl and propaquizafop in soil samples have been firstly performed using ultra high performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). Thus, metabolites or degradation products, such as CHHQ (dihydroxychloroquinoxalin), CHQ (6-chloroquinoxalin-2-ol), PPA ((R)-2-(4-hydroxyphenoxy)propionic acid) and 2,3-dihydroxyquinoxaline were also monitored. An extraction procedure based on QuEChERS procedure was used...
July 7, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28678407/homochiral-metal-organic-frameworks-based-on-amino-acid-ligands-for-hplc-separation-of-enantiomers
#16
Jun-Hui Zhang, Rui-Yu Nong, Bang-Jin Wang, Ping Ai, Sheng-Ming Xie, Li-Ming Yuan
Natural amino acids are well known to form coordination polymers with transition metal ions. In this study, six homochiral metal-organic frameworks constructed from Zn(2+) or Co(2+) ions and various enantiopure amino acid (L-tyrosine, L-histidine, L-tryptophan and L-glutamic acid), namely [Zn(L-tyr)]n (L-tyrZn), [Zn4 (btc)2 (Hbtc)(L-His)2 (H2 O)4 ]·1.5H2 O, {[Zn2 (L-trp)2 (bpe)2 (H2 O)2 ]·2H2 O·2NO3 }n , [Co2 (L-Trp)(INT)2 (H2 O)2 (ClO4 )], [Co2 (sdba)((L-Trp)2 ] and [Co(L-Glu)(H2 O)·H2 O]∞ , were synthesized according to the methods previously reported in the literature...
July 5, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28677844/enantioselective-analysis-of-ibuprofen-enantiomers-in-mice-plasma-and-tissues-by-high-performance-liquid-chromatography-with-fluorescence-detection-application-to-a-pharmacokinetic-study
#17
Katarzyna Przejczowska-Pomierny, Monika Włodyka, Agnieszka Cios, Elżbieta Wyska
A direct fluorometric high-performance liquid chromatography (HPLC) method was developed and validated for the analysis of ibuprofen enantiomers in mouse plasma (100 μl) and tissues (brain, liver, kidneys) using liquid-liquid extraction and 4-tertbutylphenoxyacetic acid as an internal standard. Separation of enantiomers was accomplished in a Chiracel OJ-H chiral column based on cellulose tris(4-methylbenzoate) coated on 5 μm silica-gel, 250 x 4.6 mm at 22 °C with a mobile phase composed of n-hexane, 2-propanol, and trifluoroacetic acid that were delivered in gradient elution at a flow rate of 1 ml min(-1) ...
July 5, 2017: Chirality
https://www.readbyqxmd.com/read/28676874/chiroptical-properties-of-cryptophane-111
#18
Thierry Buffeteau, Delphine Pitrat, Nicolas Daugey, Nathalie Calin, Marion Jean, Nicolas Vanthuyne, Laurent Ducasse, Frank Wien, Thierry Brotin
The two enantiomers of cryptophane-111 (1), which possesses the most simplified chemical structure of cryptophane derivatives and exhibits the highest binding constant for xenon encapsulation in organic solution, were separated by HPLC using chiral stationary phases. The chiroptical properties of [CD(+)254]-1 and [CD(-)254]-1 were determined in CH2Cl2 and CHCl3 solutions by polarimetry, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) experiments and were compared to those of cryptophane-222 (2) derivative...
July 5, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28672111/analyzing-spin-selectivity-in-dna-mediated-charge-transfer-via-fluorescence-microscopy
#19
John M Abendroth, Nako Nakatsuka, Matthew Ye, Dokyun Kim, Eric E Fullerton, Anne M Andrews, Paul S Weiss
Understanding spin-selective interactions between electrons and chiral molecules is critical to elucidating the significance of electron spin in biological processes and to assessing the potential of chiral assemblies for organic spintronics applications. Here, we use fluorescence microscopy to visualize the effects of spin-dependent charge transport in self-assembled monolayers of double-stranded DNA on ferromagnetic substrates. Patterned DNA arrays provide background regions for every measurement to enable quantification of substrate magnetization-dependent fluorescence due to the chiral-induced spin selectivity effect...
July 3, 2017: ACS Nano
https://www.readbyqxmd.com/read/28671230/synthesis-and-characterization-of-two-layered-aluminophosphates-r-c8h12n-8-h2o-2%C3%A2-al8p12o48h4-and-s-c8h12n-8-h2o-2%C3%A2-al8p12o48h4-with-a-mirror-symmetric-feature-and-their-proton-conductivity
#20
Yue Yu, Jingran Zhu, Jiancong Liu, Yan Yan, Xiaowei Song
The template effect of chiral organic molecules to aluminophosphate open frameworks was investigated by the syntheses of two layered structures, [R-C8H12N]8[H2O]2·[Al8P12O48H4] and [S-C8H12N]8[H2O]2·[Al8P12O48H4] (denoted as AlPO-CJ72-R and -S), with a mirror symmetric feature. The two structures are obtained separately, which is the first instance in inorganic open-framework materials to our knowledge, by α-methylbenzylamine with homochirality. Single-crystal X-ray diffraction analysis reveals that the structure of either AlPO-CJ72-R or AlPO-CJ72-S crystallizes in the chiral triclinic space group P1, and the existence of AAAA-stacked Al2P3O12(3-) layers made up of alternating AlO4 and PO3([double bond, length as m-dash]O) or PO2([double bond, length as m-dash]O)(OH) tetrahedra to form a 4 × 6 network...
July 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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