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1983 (2)
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1978 (3)
1Author    C. Schamagl, E. Köst-Reyes, S. Schneider, H.-P Köst, H. ScheerRequires cookie*
 Title    Circular Dichroism of Chromopeptides from Phycocyanin  
 Abstract    The circular dichroism of bilipeptides from Spirulina geitleri phycocyanin is strongly solvent and pH dependent. Maximum optical activity has been observed in aqueous solutions containing urea (8 M). In aqueous buffer, a sign reversal occurred upon the change from neutral to acidic pH; in methanolic solutions shows the optical activity a strong pH dependence both with respect to sign and magnitude. These findings have been rationalized by the presence o f chrom ophore-peptide interactions, which are minim ized in the presence of urea. M olecular orbital calculations indicate that the observed sign reversal is not necessarily due to a reversal o f the chirality o f the entire chromophore, but may also result from more localized conform ational changes. 
  Reference    Z. Naturforsch. 38c, 951—959 (1983); received June 22 1983 
  Published    1983 
  Keywords    Biliproteins, Bilipeptides, Conform ation, Optical Activity, Protein Interaction 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0951.pdf 
 Identifier    ZNC-1983-38c-0951 
 Volume    38 
2Author    WolfJürgen RichterRequires cookie*
 Title    Experimentelle Prüfung von Näherungsansätzen für Chiralitätsfunktionen am Beispiel der optischen Aktivität von Methan-Derivaten im Transparenzgebiet II Semiempirical Use of Chirality Functions for the Description of the Optical Activity of Methan Derivatives in the Transparent Region II  
 Abstract    Simple alcohol derivatives are used to test approximative chirality functions experimen-tally. The approximations of the type 1 b yield a competent description of the optical rotatory power of methan-derivatives. Provided that certain restrictions of ligand inter-actions are taken into account, a set of ligand-specific parameters is obtained; however, no common set of parameters is suitable for both the alcohol and the amino-alcohol derivatives, which have been published before. 
  Reference    Z. Naturforsch. 33b, 165—172 (1978); eingegangen am 21. November 1977 
  Published    1978 
  Keywords    Chirality Functions, Optical Activity, Methan Derivatives 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0165.pdf 
 Identifier    ZNB-1978-33b-0165 
 Volume    33 
3Author    Henri Brunner, A.F M Mokhlesur RahmanRequires cookie*
 Title    Asymmetrische Katalysen, 13 [1] Chelat-Liganden und ihre Rhodium-Komplexe mit seitlichen Asymmetriezentren und ihre Anwendung in der enantioselektiven Katalyse Asymmetric Catalyses. 13 [1] Chelate Ligands and their Rhodium Complexes with Lateral Asymmetrie Centers and their Use in Enantioselective Catalysis  
 Abstract    The chelate ligands 1-3 with lateral asymmetric centers at the nitrogen atoms were prepared and characterized. In the Rh complexes 4 and 5 the asymmetric centers directly interact with those coordination positions where during enantioselective catalysis pro-chiral substrates are converted into optically active products. The compounds 4 and 5, as well as the in situ catalysts [Rh(COD)Cl]2/2 were used in the asymmetric hydrogenation of a-N[acetamino]cinnamic acid and in the asymmetric hydrosilylation of acetophenone with diphenylsilane. The low optical inductions obtained result from the catalyst loosing its chiral information during catalysis due to racemization or fragmentation. 
  Reference    Z. Naturforsch. 38b, 1332—1338 (1983); eingegangen am 16. Mai 1983 
  Published    1983 
  Keywords    Optical Activity, Asymmetrie Induction, Enantioselective Catalysis 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-1332.pdf 
 Identifier    ZNB-1983-38b-1332 
 Volume    38 
4Author    Henri Brunner, Manfred Muschiol, Wilfried NowakRequires cookie*
 Title    Optisch aktive Übergangsmetall-Komplexe, LVII [1]  
 Abstract    (+)-und (—)-C5H5M(CO)(P02R*)X mit M = Fe, "Fe und X = 1, COCH3, CH3 Optically Active Transition Metal Complexes, LVII [1] (+)-and (—)-C5H5M(CO)(P02R*)X with M = Fe, "Fe, and X = I, COCH3, CH3 In the reaction of C5H5Fe(CO)2l and CsHsFefCO^CHa, respectively, with S-(+)-(C6H5)2PN(CH3)CH(CH3)(C6H5) (abbreviated P02R*) the complexes C5H5Fe(CO)(P02R*)I(l),C5H5Fe(CO)(P02R*)COCH3(2),andC5H5Fe(CO)(P02R !,t)CH3(3) are formed as pairs of diastereoisomers the components of which differ only in the configu-ration at the iron atom. CsH5Fe(CO)(P02R*)CH3 (3) can be obtained in higher yield by photochemical decarbonylation of C5H5Fe(CO)(P02R*)COCH3 (2). The (+)s85-and (—)365-diastereoisomers of each pair exhibit different chemical shifts in the X H NMR spectra. Diastereoisomer separation can be achieved by fractional crystallization. Starting with 57 Fe metal (—)365-C5H5 57 Fe(CO)(P02R*)I was prepared via 57 FeI2, 57 Fe(CO)4l2, C5H5 57 Fe(CO)2l, and C5H5 57 Fe(CO)(P02R*)I in order to demonstrate optical activity of a 57 Fe compound in the y region by Mössbauer polarimetry in later experiments to be reported elsewhere. 
  Reference    Z. Naturforsch. 33b, 407—411 (1978); eingegangen am 24. Januar 1978 
  Published    1978 
  Keywords    Diastereoisomer Separation, X H NMR, Optical Activity, Transition Metal Complexes 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0407.pdf 
 Identifier    ZNB-1978-33b-0407 
 Volume    33 
5Author    Hermann Rau, Otto SchusterRequires cookie*
 Title    Eine theoretische Begründung empirischer Sektorenregeln der optischen Aktivität Theoretical Verification of Empirical Sector Rules of Optical Activity  
 Abstract    A simple procedure for derivation of octant rules for optically active molecules con-taining a chromophoric group is developed within the framework of Kuhn's classical model of coupled oscillators. The important feature in this derivation is the clue that the locus of the center of gravity of the atoms not belonging to the chromophoric group and the direction of maximum polarizability of this ensemble of atoms are not independent. The octant rule for carbonyl compounds arrived at by this procedure is in agreement with the empirical one. A newly derived rule for cis-azo compounds is verified by empirical data. 
  Reference    Z. Naturforsch. 34b, 1519—1524 (1979); eingegangen am 24. Juli 1979 
  Published    1979 
  Keywords    Optical Activity, Coupled Oscillator Model, Theoretical Sector Rules, cis-azo Compounds 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1519.pdf 
 Identifier    ZNB-1979-34b-1519 
 Volume    34 
6Author    Henri Brunner, Heinz VogtRequires cookie*
 Title    Optically Active Transition Metal Complexes, LIX [1]  
 Abstract    The pair of diastereoisomers (+)436-and (—)436-C5H5Fe(CO)(COCH3)P02R*, with P02R* = (S)-(+)-(C6H5)2PN(CH3)CH(CH3)(C6H5), can be separated into its components by preparative liquid chromatography under pressure. On heating (+)436-C5H5Fe(CO)-(COCH3)P02R* equilibrates with C5H5Fe(CO)2CH3 and P02R* before epimerization at the Fe [atom takes place. In the same way, the equilibrium C5H5Fe(CO)(COCH3)P(C6Hs)3 C5H5Fe(CO)2CH3 + P(C6Hs)3 can be obtained starting from either side. It is shown that the decarbonylation C5H5Fe(CO)(COCH3)P(C6H5)3 C5H5Fe(CO)(CH3)P(C6H5)3 + CO is not a thermal but a photochemical reaction. 
  Reference    Z. Naturforsch. 33b, 1231—234 (1978); eingegangen am 6. Juli 1978 
  Published    1978 
  Keywords    Diastereoisomer Separation, Preparative Liquid Chromatography, 1 H NMR, Optical Activity, Transition Metal Complexes 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-1231.pdf 
 Identifier    ZNB-1978-33b-1231 
 Volume    33 
7Author    Henri Brunner, MonikaE. Dylla, GabrieleA M Hecht, Willigis PieronczykRequires cookie*
 Title    Synthese von ß-Diphenylphosphin-carbonyl-Verbindungen durch Umsetzung von Brommethyl-earbonyl-Verbindungen mit Diphenyl(trimethylsilyl)phosphin Synthesis of /9-Diphenylphosphine-carbonyl Compounds by Reaction of Bromomethyl-carbonyl Compounds with Diphenyl(trimethylsilyl)phosphine  
  Reference    Z. Naturforsch. 37b, 404—406 (1982); eingegangen am 13. November 1981 
  Published    1982 
  Keywords    /3-Keto-phosphines, Amino-phosphines, Imino-phosphines, Synthesis, NMR Spectra, Optical Activity 
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 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0404.pdf 
 Identifier    ZNB-1982-37b-0404 
 Volume    37