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CD and ACD spectroscopy on anisotropic samples: chirality of oriented molecules and anisotropic phases--a critical analysis. 各向异性样品的CD和ACD光谱:定向分子的手性和各向异性相——一个关键的分析。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212880
H. Kuball
{"title":"CD and ACD spectroscopy on anisotropic samples: chirality of oriented molecules and anisotropic phases--a critical analysis.","authors":"H. Kuball","doi":"10.1080/10242430212880","DOIUrl":"https://doi.org/10.1080/10242430212880","url":null,"abstract":"Chiral anisotropic phases exhibit an elliptical birefringence and dichroism instead of the circular effects of isotropic dissymmetric and the linear effects of achiral anisotropic phases. Therefore, techniques to determine chiral effects of chiral anisotropic phases yield not always results of chirality measurements, namely, pseudoscalar quantities. From definitions for a chirality measurement with non-oriented and oriented macroscopic anisotropic phases procedures are derived by which the pseudoscalar contribution included in the elliptical birefringence and dichroism can be obtained. Within this description the CD of chiral microcrystallites, isotropically distributed in pressed KBr plates or in Nujol, is a chirality measurement. With an excess of anisotropic distributed material in pressed KBr plates or, in general, with oriented macroscopic anisotropic phases, the ACD is no longer a pseudoscalar. An achiral information is included in the ACD which is not an artifact obtained by the mixing of \"circular and linear effects\" via nonideal optical elements in a CD spectrometer.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"7 1","pages":"197-205"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78816457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 16
Circular dichroism spectra of regioregular poly[3 [(S)-2-methylbutyl]-thiophene] and of poly[3,4-di[(S)-2-methylbutyl]-thiophene]. 区域规则聚[3 [(S)-2-甲基丁基]-噻吩]和聚[3,4-二[(S)-2-甲基丁基]-噻吩]的圆二色光谱。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212881
F. Lebon, G. Longhi, S. Abbate, M. Catellani, F. Wang, P. Polavarapu
{"title":"Circular dichroism spectra of regioregular poly[3 [(S)-2-methylbutyl]-thiophene] and of poly[3,4-di[(S)-2-methylbutyl]-thiophene].","authors":"F. Lebon, G. Longhi, S. Abbate, M. Catellani, F. Wang, P. Polavarapu","doi":"10.1080/10242430212881","DOIUrl":"https://doi.org/10.1080/10242430212881","url":null,"abstract":"Ultraviolet absorption and Circular Dichroism spectra in the region 300-700 nm for highly regioregular samples of Poly[3[(S)-2-methylbutyl]-thiophene] are reported for solutions in good and poor solvents, at variable temperature, and for films in various conditions. In the latter case novel CD data up to the melting temperature provide some hints for the self-assembling process towards supramolecular organization. UV-visible and CD data are also reported on the related polymer Poly[3,4-di[(S)-2-methylbutyl]-thiophene].","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"12 1","pages":"207-12"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87079681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 8
Chiral crystallization of anti-dodecaisopropyltricyclo-[4.2.00.0(2,5)] octasilane. 反十二烷基异丙基三环-[4.2.00.0(2,5)]辛烷的手性结晶。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212882
R. Tanaka, S. Kyushin, M. Unno, H. Matsumoto
{"title":"Chiral crystallization of anti-dodecaisopropyltricyclo-[4.2.00.0(2,5)] octasilane.","authors":"R. Tanaka, S. Kyushin, M. Unno, H. Matsumoto","doi":"10.1080/10242430212882","DOIUrl":"https://doi.org/10.1080/10242430212882","url":null,"abstract":"The aim of this article is to describe the results of our investigation on the chiral crystallization of anti-tricyclic ladder polysilane, anti-dodecaisopropyltricyclo [4.2.0.0(2,5)] octasilane (1). In solid state, the silicon framework of 1 adopts twisted conformation in which the Si4 rings are puckered in the same direction. Crystallization of 1 afforded a large conglomerate crystal in high yield. X-ray crystallography revealed that the crystal consists of either right-handed (P) or left-handed (M) molecules. The ultraviolet and circular dichroism spectra of the chiral crystals of 1 reveal two absorption bands in the 400-250 nm region.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"18 1","pages":"157-9"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72931829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Crystalline state conformation of 2-methoxy-2-(1-naphthyl)propionic acid ester. 2-甲氧基-2-(1-萘基)丙酸酯的结晶构象。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212879
Takuma Fujita, S. Kuwahara, Masataka Watanabe, N. Harada
{"title":"Crystalline state conformation of 2-methoxy-2-(1-naphthyl)propionic acid ester.","authors":"Takuma Fujita, S. Kuwahara, Masataka Watanabe, N. Harada","doi":"10.1080/10242430212879","DOIUrl":"https://doi.org/10.1080/10242430212879","url":null,"abstract":"The enantioresolution method using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid 1) was applied to 1,2,3,4-tetrahydro-4-phenanthrenol (4). Racemic alcohol (+/-)-4 was esterified with (S)-(+)-1, and a diastereomeric mixture of esters formed was separated by HPLC on silica gel giving the first-eluted ester 5a and the second-eluted one 5b. Ester 5a was reduced with LiAlH4 yielding enantiopure alcohol (+)-4. A single crystal of ester 5a was subjected to X-ray crystallography to determine its absolute configuration as (S,S), and therefore to assign the S absolute configuration to (+)-4. The most striking finding in the X-ray analysis is that the methoxyl oxygen atom is syn to the ester carbonyl oxygen even in the crystalline state. This is just the preferred conformation of MalphaNP acid esters assumed in the 1H NMR anisotropy method. The S absolute configuration of (+)-4 was also confirmed by the CD and 1H NMR anisotropy methods.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"79 10 1","pages":"219-23"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85938058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 15
Fluorescence-detected circular dichroism by modulated beam in the wavelength axial direction. 通过波长轴向调制光束荧光检测圆二色性。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212875
A. Yamamoto, S. Kodama, A. Matsunaga, H. Nakazawa, K. Hayakawa
{"title":"Fluorescence-detected circular dichroism by modulated beam in the wavelength axial direction.","authors":"A. Yamamoto, S. Kodama, A. Matsunaga, H. Nakazawa, K. Hayakawa","doi":"10.1080/10242430212875","DOIUrl":"https://doi.org/10.1080/10242430212875","url":null,"abstract":"A novel device is described that permits fluorescence-detected circular dichroism (FDCD) detection in a conventional fluorescence spectrophotometer. FDCD is a phenomenon in which the emission intensity of a chiral analyte depends on the polarization state of the excitations. Although FDCD is a sensitive chiral detection technique, measurement of FDCD by using a special CD spectrometer has involved many difficulties. The proposed device consists of a polarizing prism and a retardation plate that fit on the excitation light side in the sample compartment of the fluorescence spectrophotometer. In this method, a FDCD wave superimposed on the fluorescence excitation spectrum of a chiral analyte was detected. We have also demonstrated the possibility of the enantiomeric purity determination of chiral analytes in real samples.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"25 1","pages":"225-9"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85316788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Circular dichroism of amino acid films in UV-VUV region. 氨基酸膜在UV-VUV区的圆二色性。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212884
Masahito Tanaka, Y. Kodama, K. Nakagawa
{"title":"Circular dichroism of amino acid films in UV-VUV region.","authors":"Masahito Tanaka, Y. Kodama, K. Nakagawa","doi":"10.1080/10242430212884","DOIUrl":"https://doi.org/10.1080/10242430212884","url":null,"abstract":"Circular dichroism (CD) spectra of sublimated films of alanine and alanine dipeptide were measured in UV-VUV region. When a film has some linear anisotropy, the apparent CD signal is known to be strongly distributed by linear anisotropy. In order to obtain the true CD spectra, we examined this disturbance for L-alanine films. We measured linear dichroism spectra and CD spectra as a function of the sample rotation angle, turning the sample over. On the basis of these measurements, we concluded that the linear anisotropy contribution to CD was sufficiently small for carefully prepared films. In addition, we revealed that it is essential for accurate measurement to prepare thin film of which thickness is smaller than 100 nm for the case of alanine films. CD of amino acid films was compared with that of aqueous solution. Sign of CD signal of solid films was observed to be the same for aspartic acid, but it was reversed from that of aqueous solution for alanine and alanine dipeptide.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"14 1","pages":"185-90"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84328231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
Comparison of CD spectra of (2-methylphenyl)- and (2,6-dimethylphenyl)-phenylmethanols leads to erroneous absolute configurations. 比较(2-甲基苯基)-和(2,6-二甲基苯基)-苯甲醇的CD光谱会导致错误的绝对构型。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212878
M. Kosaka, S. Kuwahara, Masataka Watanabe, N. Harada, Gabriel E. Job, W. H. Pirkle
{"title":"Comparison of CD spectra of (2-methylphenyl)- and (2,6-dimethylphenyl)-phenylmethanols leads to erroneous absolute configurations.","authors":"M. Kosaka, S. Kuwahara, Masataka Watanabe, N. Harada, Gabriel E. Job, W. H. Pirkle","doi":"10.1080/10242430212878","DOIUrl":"https://doi.org/10.1080/10242430212878","url":null,"abstract":"Enantiopure (2,6-dimethylphenyl)phenylmethanol (+)-(3) and analog (+)-(4) were prepared and their CD spectra were found opposite to that of (2-methylphenyl)phenylmethanol (R)-(-)-(2), the absolute configuration of which was previously established by X-ray crystallography. Therefore the S absolute configuration was once assigned to (+)-3 and (+)-4. After that we have succeeded in the X-ray analyses of chiral dichlorophthalate esters of (+)-3 and (+)4, which clearly indicated R absolute configuration. It is thus evident that comparison of the CD spectra of alcohols 2, 3, and 4 leads to erroneous absolute configurations.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"39 1","pages":"213-7"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81545904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
High-performance photoelastic modulator for polarization modulation spectrometer. 用于偏振调制光谱仪的高性能光弹性调制器。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212885
S. Maeda, K. Nakae, Y. Shindo
{"title":"High-performance photoelastic modulator for polarization modulation spectrometer.","authors":"S. Maeda, K. Nakae, Y. Shindo","doi":"10.1080/10242430212885","DOIUrl":"https://doi.org/10.1080/10242430212885","url":null,"abstract":"A high-performance photoelastic modulator (PEM) has been built. It consists of a home-made PEM head and a home-built PEM driver that is based on the principle of the phase-locked loop (PLL) (PLL PEM driver). It was installed in our new type circular dichroism (CD) spectrometer for visible light region and its performance was evaluated. With the phase angle being set exactly to zero, the PEM is found to be about eight times more efficient than commercially available one. The efficiency of PEM depends not only on the efficiency of PEM driver but also on the quality of PEM head. The latter can be estimated from admittance-parameter measurements without installing it into a spectrometer. With substituting the PLL PEM driver for a conventional one, the PEM drive voltage can be reduced from one-half to one-third and the baseline shift for air blank that is a measure of the total performance of polarization modulation spectrometers becomes quite small.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"82 1","pages":"175-83"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75632749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Vibrational circular dichroism in the near infrared: instrumental developments and applications. 近红外的振动圆二色性:仪器的发展和应用。
Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212877
E. Castiglioni, F. Lebon, G. Longhi, S. Abbate
{"title":"Vibrational circular dichroism in the near infrared: instrumental developments and applications.","authors":"E. Castiglioni, F. Lebon, G. Longhi, S. Abbate","doi":"10.1080/10242430212877","DOIUrl":"https://doi.org/10.1080/10242430212877","url":null,"abstract":"Near infrared vibrational circular dichroism spectra in the region of 1300 to 800 nm were recorded for 12 enantiomeric pairs of molecules with a home-made dispersive apparatus. With respect to earlier measurements, a better signal-to-noise ratio was obtained, thus allowing a more precise determination of molecular parameters. A detailed examination of the spectra between 1300 and 1100 nm allowed us to correlate the data of the different molecules, based on local properties of given molecular moieties. The relevance of this correlation in configurational and/or conformational studies is discussed.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"48 1","pages":"161-73"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86749534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 30
Chiral inclusion crystals constructed with achiral host and achiral guest molecules. 由非手性宿主和非手性客体分子构建的手性包合晶体。
Enantiomer Pub Date : 2002-03-01 DOI: 10.1080/10242430212198
F. Toda
{"title":"Chiral inclusion crystals constructed with achiral host and achiral guest molecules.","authors":"F. Toda","doi":"10.1080/10242430212198","DOIUrl":"https://doi.org/10.1080/10242430212198","url":null,"abstract":"Achiral molecules of tetrakis(p-bromophenyl)ethylene and 2,3,6,7,10,11-hexahydroxy triphenylene were found to arrange in a chiral form in their inclusion crystal with an achiral guest molecule. The chiral arrangement of these achiral molecules was studied by X-ray analysis and CD spectral measurement in the solid state.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"7 1","pages":"59-65"},"PeriodicalIF":0.0,"publicationDate":"2002-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80963217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
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