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Chirality

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https://read.qxmd.com/read/30859633/indirect-synchronous-fluorescence-spectroscopy-and-direct-high-performance-thin-layer-chromatographic-methods-for-enantioseperation-of-zopiclone-and-determination-of-chiral-switching-eszopiclone-evaluation-of-thermodynamic-quantities-of-chromatographic-separation
#1
Bahia A Moussa, Nadia F Youssef, Ehab F Elkady, Marwa F Mohamed
Economic and enantioselective synchronous fluorescence spectroscopy and high-performance thin-layer chromatography methods have been developed and validated as per ICH guidelines for the separation of zopiclone enantiomers using L-(+)-tartaric acid as a chiral selector, followed by determination of the chiral-switching eszopiclone. Synchronous fluorescence spectroscopy was successfully applied for chiral recognition of R & S enantiomers of zopiclone at ∆λ = 110 nm based on creating of diastereomeric complexes with 0...
March 12, 2019: Chirality
https://read.qxmd.com/read/30849198/ultra-performance-convergence-chromatography-with-tandem-mass-spectrometry-assisted-method-for-rapid-enantioseparation-and-determination-of-fluazifop-butyl-in-tobacco-and-soil
#2
Fei Yang, Gangling Tang, Shanshan Liu, Ziyan Fan, Ying Wang, Huimin Deng, Zhaoyang Bian, Zhonghao Li
A quick, green, and sensitive method for chiral separation and determination of fluazifop-butyl enantiomers in tobacco and soil was established by ultra-performance convergence chromatography with tandem mass spectrometry (UPC2 -MS/MS). The baseline separation was obtained on an ACQUITY UPC2 Trefoil CEL2 column in 4 minutes with CO2 and methanol as mobile phase. Column temperature, auto back pressure regulator pressure (ABPR), and modifier solvent were optimized to obtain the best separation efficiency. Under the optimal conditions, the recoveries of both enantiomers were 82...
March 8, 2019: Chirality
https://read.qxmd.com/read/30801797/two-desired-epitopes-of-ctni-benefit-for-preparation-of-standardized-monoclonal-antibodies
#3
JunJie Yan, QiLing Yang, WenLi Li, Juan Yu, Jun Xie, JunJian Xiang, Hong Wang
Acute myocardial infarction (AMI) is one of the most severe cardiovascular diseases in humans, often resulting in unexpected death. Early detection is critical for patient survival. Sandwich ELISA is a common method for the detection of AMI. However, ELISA kits from different manufacturers can give different results, in part because of the lack of standardized epitopes. Therefore, the purpose of this study was to find two standardized epitopes. We predicted two antigen epitopes and respectively immunize mice to manufacture standardized monoclonal antibodies...
February 22, 2019: Chirality
https://read.qxmd.com/read/30753757/1-hydroxymethyl-7-oxabicyclo-2-2-1-hept-2-ene-skeleton-in-enantiopure-form-through-enzymatic-kinetic-resolution
#4
U Chandrasekhar Reddy, Muraleedharan K Manheri
No abstract text is available yet for this article.
February 12, 2019: Chirality
https://read.qxmd.com/read/30753745/circularly-polarized-luminescence-of-sm-iii-and-eu-iii-complexes-with-chiral-ligand-r-s-binapo
#5
Daniel Cotter, Spencer Dodder, Valentine J Klimkowski, Todd A Hopkins
Luminescent lanthanide (III) ions have been exploited for circularly polarized luminescence (CPL) for decades. However, very few of these studies have involved chiral samarium (III) complexes. Complexes are prepared by mixing axial chiral ligands (R/S))-2,2'-bis(diphenylphosphoryl)-1,1'-binaphthyl (BINAPO) with europium and samarium Tris (trifluoromethane sulfonate) (Eu (OTf)3 and Sm (OTf)3 ). Luminescence-based titration shows that the complex formed is Ln((R/S)-BINAPO)2 (OTf)3 , where Ln = Eu or Sm. The CPL spectra are reported for Eu((R/S)-BINAPO)2 (OTf)3 and Sm((R/S)-BINAPO)2 (OTf)3 ...
February 12, 2019: Chirality
https://read.qxmd.com/read/30702777/green-synthesis-of-enantiopure-quinoxaline-alcohols-using-daucus-carota
#6
Sneha H Meshram, Tungana Ramesh, Jagadeesh Babu Nanubolu, Ajay Kumar Srivastava, Bhaskar Rao Adari, Nivedita Sahu
Green chemistry comprises a new approach in the synthesis of biologically active compounds using biocatalysts, thus diminishing the hazards for human health and environmental pollution. Asymmetric bioreduction is one of the most widely employed strategies in chemoenzymatic synthesis to produce enantiomerically pure chiral alcohols. The present study highlights the use biocatalyst Daucus carota for selective bioreduction of quinoxaline ketones 1a-6a to their corresponding optically pure alcohols 1b-6b in high yields (up to 84%) and good enantioselectivity (up to 98%)...
January 31, 2019: Chirality
https://read.qxmd.com/read/30702776/in-defense-of-louis-pasteur-critique-of-gerald-geison-s-deconstruction-of-pasteur-s-discovery-of-molecular-chirality
#7
REVIEW
Joseph Gal
Louis Pasteur discovered the phenomenon of molecular chirality, based on his studies of tartrate crystals. His finding remains one of the most important discoveries in the history of chemistry and a fundamentally important chemical phenomenon, with essential implications in biology. In his 1995 book The Private Science of Louis Pasteur, the eminent historian of science Gerald L. Geison (1943-2001) was highly critical of much of Pasteur's work including his discovery of molecular chirality. The in-depth analysis provided in this article indicates, however, that the negative assessment of Pasteur's chirality work by Geison is entirely without scientific basis...
January 31, 2019: Chirality
https://read.qxmd.com/read/30702775/design-synthesis-and-application-of-chiral-tetraoxacalix-2-arene-2-triazine-based-organocatalysts-in-asymmetric-michael-addition-reactions
#8
Hayriye Nevin Genc, Ummu Ozgun, Abdulkadir Sirit
A novel type of oxacalix[2]arene[2]triazine-based organocatalysts for asymmetric Michael reactions are reported for the first time. Chiral subunits were attached to the heteroatom-bridged calixaromatic platform by a reaction of (R)- and (S)-1-aminotetraline with tetraoxacalix[2]arene[2]triazine in both enantiomeric forms. To evaluate the catalytic efficiency of the novel organocatalysts, isobutyraldehyde reacted with various substituted and unsubstituted aromatic trans-β-nitrostyrenes in tetrahydrofuran (THF), leading to Michael adducts in excellent yields and enantioselectivites (up to 97% yield and 99% ee)...
January 31, 2019: Chirality
https://read.qxmd.com/read/30702773/chromatographic-approach-to-study-the-configurational-stability-of-ni-ii-complexes-of-amino-acid-schiff-bases-possessing-stereogenic-nitrogen
#9
Jianlin Han, Marion Jean, Christian Roussel, Hiroki Moriwaki, Vadim A Soloshonok
Herein, we disclose the design of a model Ni(II) complex of glycine Schiff base possessing single-nitrogen stereogenic center, which was successfully used for high-performance liquid chromatography (HPLC)-assisted assessment of its configurational stability. The major finding is that the configurational stability of the Ni(II)-coordinated nitrogen is profoundly dependent on the reaction conditions used, in particular the solvent, and can range from inconsequential (t½ less than 5 min) to virtually completely stable (t½ 90 y)...
January 31, 2019: Chirality
https://read.qxmd.com/read/30693982/preparation-and-characterization-of-a-new-open-tubular-capillary-column-for-enantioseparation-by-capillary-electrochromatography
#10
Yingjie Li, Yimin Tang, Shili Qin, Xue Li, Qiang Dai, Lidi Gao
In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9 (34 )...
January 29, 2019: Chirality
https://read.qxmd.com/read/30677171/enantioseparation-of-chiral-pharmaceuticals-by-vancomycin-bonded-stationary-phase-and-analysis-of-chiral-recognition-mechanism
#11
Jiaxi Li, Ruixia Liu, Liyang Wang, Xiaoling Liu, Hongjie Gao
The drug chirality is attracting increasing attention because of different biological activities, metabolic pathways, and toxicities of chiral enantiomers. The chiral separation has been a great challenge. Optimized high-performance liquid chromatography (HPLC) methods based on vancomycin chiral stationary phase (CSP) were developed for the enantioseparation of propranolol, atenolol, metoprolol, venlafaxine, fluoxetine, and amlodipine. The retention and enantioseparation properties of these analytes were investigated in the variety of mobile phase additives, flow rate, and column temperature...
January 24, 2019: Chirality
https://read.qxmd.com/read/30672609/the-different-dissipation-behavior-of-chiral-pesticide-paclobutrazol-in-the-brine-during-chinese-cabbage-pickling-process
#12
Yue Zhao, Meinan Ouyang, Yabing Xiong, Dandan Wang, Haoming Guo, Zhonghua Yang
Paclobutrazol (PBZ) is a kind of chiral pesticide, which is a plant growth regulator and has fungicidal activity. Because of the steric-hindrance effect, there are two enantiomers (2S, 3S; 2R, 3R) in the production. This research studied on the dissipation behavior of chiral pesticide PBZ in the brine during the Chinese cabbage pickled process by phase column-high performance liquid chromatography (HPLC). The result demonstrated the PBZ enantiomers had the different dissipation in the brine. The study on the behavior of chiral pesticide PBZ in food may provide more sufficient data and information for understanding the potential risk in food and evaluating the environmental pollution at the enantiomer level...
January 23, 2019: Chirality
https://read.qxmd.com/read/30667556/enantioselective-liquid-liquid-extraction-of-dl-mandelic-acid-using-chiral-diphosphine-ligands-as-extractants
#13
Yu Ma, Xiong Liu, Wenqi Zhou, Ting Cao
In order to expand the application range of chiral diphosphine ligands, (S)-BINAP, (S)-SEGPHOS, and (S)-MeO-BIPHEP were employed as extractants to recognize DL-mandelic acid. The results indicated that (S)-SEGPHOS-Cu exhibited considerable ability to recognize DL-mandelic acid with operational enantioselectivity (α) of 2.677. The process of extraction of DL-mandelic acid using (S)-SEGPHOS-Cu as extractant was systematically investigated. Performance factor (pf) was adopted to comprehensively evaluate the extraction...
January 22, 2019: Chirality
https://read.qxmd.com/read/30664264/enantiomeric-assay-of-escitalopram-s-enantiomer-and-its-in-process-impurities-using-two-different-techniques
#14
Suzan Mahmoud Soliman
The enantiomeric purity of escitalopram oxalate ESC and its "in-process impurities," namely, ESC-N-oxide, ESC-citadiol, and R(-)-enantiomer were studied in drug substance and products using high-performance liquid chromatography (HPLC)-UV (Method I), synchronous fluorescence spectroscopy (SFS) (Method IIA), and first derivative SFS (Method IIB). Method I describes as an isocratic HPLC-UV for the direct resolution and determination of enantiomeric purity of ESC and its "in-process impurities." The proposed method involved the use of αl -acid glycoprotein (AGP) chiral stationary phase...
January 21, 2019: Chirality
https://read.qxmd.com/read/30653738/chiral-porphyrin-imine-manganese-complex-as-catalyst-for-asymmetric-epoxidation-of-styrene-derivatives
#15
Nallamuthu Ananthi, I V Muthu Vijayan Enoch
New chiral porphyrin imine was synthesized from (S)-3-benzyl-2-methyl-4-phenylbutanal according to dipyrromethane method using trifluoroacetic acid, BF3 etherate, and p-chloranil. Manganese complex of this chiral porphyrin imine ligand was used as catalyst in the asymmetric epoxidation of styrene derivatives possessing different substituents. Styrene derivatives possessing electron withdrawing groups gave the corresponding chiral epoxides in high yield up to 98% and ee up to 99%. The mechanism for the catalytic asymmetric epoxidation was also discussed based on transfer of oxygen...
January 17, 2019: Chirality
https://read.qxmd.com/read/30653718/preparation-of-cadmium-sulfide-nanoparticles-and-their-application-for-improving-the-properties-of-the-electrochemical-sensor-for-the-determination-of-enrofloxacin-in-real-samples
#16
Liu Yuting, Zhang Jing, Li Donghui
An advanced electrochemical sensor for the detection of enrofloxacin (ENR) based on the use of a modified electrode containing cadmium sulfide (CdS) nanoparticles (NPs) is reported. The CdS NPs were synthesized and characterized and then coated onto the electrode to fabricate a modified electrode that exhibited a lower limit of detection of 9.5 × 10-8  mol·L-1 . This detection limit compares with a traditional electrode that exhibited a concentration detection range of 1.0 × 10-2 to 1.0 × 10-7  mol·L-1 ...
January 17, 2019: Chirality
https://read.qxmd.com/read/30653711/chiral-separation-of-aliphatic-primary-amino-alcohols-as-o-phthaldialdehyde-mercaptoethanol-derivatives-on-polysaccharide-based-chiral-stationary-phases
#17
Michal Douša
A sensitive chiral high performance liquid chromatography (HPLC) method for the determination of aliphatic primary amino alcohol isomers with o-phthaldialdehyde/mercaptoethanol precolumn derivatization has been developed and validated. Seven chiral columns were tested in a reversed phase mode. Excellent enantioseparation with the resolution more than 2.0 was achieved on Chiralcel OJ-3R. The effect of various chromatographic conditions including column temperature, acetonitrile content in the mobile phase, buffer pH, buffer concentration, and buffer type in the mobile phase on the retention and the selectivity was investigated...
January 17, 2019: Chirality
https://read.qxmd.com/read/30633388/enantiomeric-separation-of-prothioconazole-and-prothioconazole-desthio-on-chiral-stationary-phases
#18
Hui Liu, Wei Ding
Prothioconazole is a type of broad-spectrum triazole thione fungicide developed by the Bayer Company. Prothioconazole-desthio is the main metabolite of prothioconazole in the environment. In our study, enantiomeric separation of prothioconazole and prothioconazole-desthio was performed on various chiral stationary phases (CSPs) by high-performance liquid chromatography (HPLC). It was found that polysaccharide CSPs showed better ability than brushing CSPs in enantiomeric separation. The successful chiral separation of prothioconazole could be achieved on self-made Chiralcel OD, commercialized Chiralcel OJ-H and Lux Cellulose-1...
January 11, 2019: Chirality
https://read.qxmd.com/read/30633381/hplc-with-cellulose-tris-3-5-dimethylphenylcarbamate-chiral-stationary-phase-influence-of-coating-times-and-coating-amount-on-chiral-discrimination
#19
Qiuhong Wei, Hongjiu Su, Diannan Gao, Shudong Wang
Coating cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC) on silica gels with large pores have been demonstrated as an efficient way for the preparation of chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). During the process, a number of parameters, including the type of coating solvent, amount of coating, and the method for subsequent solvent removing, have been proved to affect the performance of the resultant CSPs. Coating times and the concentration of coating solution, however, also makes a difference to CSPs' performance by changing the arrangement of cellulose derivatives while remaining the coating amount constant, have much less been studied before, and thereby, were systematically investigated in this work...
January 11, 2019: Chirality
https://read.qxmd.com/read/30633374/whole-cell-application-of-lactobacillus-paracasei-bd101-to-produce-enantiomerically-pure-s-cyclohexyl-phenyl-methanol
#20
Engin Şahin, Hüseyin Serencam, Enes Dertli
In this study, a total of 10 bacterial strains were screened for their ability to reduce cyclohexyl(phenyl)methanone 1 to its corresponding alcohol. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent L paracasei BD101, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of cyclohexyl(phenyl)methanone (1) by L paracasei BD101 gave (S)-cyclohexyl(phenyl)methanol (2) with 92% yield and >99% enantiomeric excess...
January 11, 2019: Chirality
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