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'Chirality' in keywords
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1Author    Alfred KlemmRequires cookie*
 Title    Monochiralities Caused by Sexuality  
 Abstract    It is shown how the interaction of sexuality and chirality causes monochiralities of the biosphere. In [1], Rikken and Raupach say: "We show experimen-tally that magnetochiral anisotropy can give rise to an enan-tiomeric excess in a photochemical reaction driven by unpolarized light in a parallel magnetic field, which sug-gests that this effect may have played a role in the origin of the homochirality of life."* Also the fact that outside the tropics the sun goes always to the right (left) on the northern (southern) hemisphere suggests that this effect may, via the sun-dependent growth of organisms, have played a role in the origin of the homochirality of life. 
  Reference    Z. Naturforsch. 55a, 978 (2000); received November 23 2000 
  Published    2000 
  Keywords    Evolution, Sexuality, Chirality 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0978_n.pdf 
 Identifier    ZNA-2000-55a-0978_n 
 Volume    55 
2Author    Dainis Dakternieks, Gerd-Volker Röschenthaler, Reinhard SchmutzlerRequires cookie*
 Title    Synthesis of Chiral and Non-chiral Phosphites Containing the Hexafluoroisopropoxy Group  
 Abstract    A series of new phosphorus (III) compounds containing the hexafluoroisopropoxide group has been synthesised by reacting halophosphines with lithium hexafluoroisoprop-oxide. The phosphites Bu<PX[OCH(CF3)2] (where X = F, Cl), Bu«MeP[OCH(CF3)2] and C6HsPF[OCH(CF3)2] each contain a chiral center at phosphorus. 
  Reference    Z. Naturforsch. 33b, 507—510 (1978); received February 13 1978 
  Published    1978 
  Keywords    Phosphites, Halophosphites, Chirality, Lithium Hexafluoroisopropoxide 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0507.pdf 
 Identifier    ZNB-1978-33b-0507 
 Volume    33 
3Author    Amelia Thereza, Roberto Soares3, Ricardo Dias Lins3, RichardG. Longo3, Ricardo Arrattb, Ferreira3Requires cookie*
 Title    Plural Origins of Molecular Homochirality in Our Biota Part II. The Relative Stabilities of Homochiral and Mixed Oligoribotides and Peptides  
 Abstract    By computer simulations -molecular mechanics and molecular dynamics with the amber force field (Weiner et al., (1986), J. Comp. Chem. 7, 2 3 0 -2 5 2) -we have determined the stabilities of oligoribotide strands built with d -and L-riboses, and of peptide chains with d -and L-amino acid residues. In particular, complementary double-chains of oligoribotides were studied, since they are an important feature of the growing mechanism o f modern nucleic acids. Peptide chains on the other hand, grow without need of a template. We found that mixed oligoribotides are less stable than homochiral ones, and that this chiral effect is less noticeable in peptide chains. The results support the interpretation that L-riboses act as termi­ nators to the template-assisted growth of oligo-r-GD (enantiomeric cross-inhibition; Joyce et al., (1987), Proc. Natl. Acad. Sei. U S A 84, 4 398-4402). Based on this effect, a chemical pathway is proposed which could, under assumed prebiotic conditions, bypass the hindrance of homochiral growth. 
  Reference    Z. Naturforsch. 52c, 89 (1997); received July 10/September 4 1996 
  Published    1997 
  Keywords    Chirality, Peptides, Oligoribotides, Computer Simulations 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0089.pdf 
 Identifier    ZNC-1997-52c-0089 
 Volume    52 
4Author    I. D. Ierking1, F. G. Ießelm Ann1, P. Zugenm, H. R2, H. Z. Aschke2, W. Kuczynski3Requires cookie*
 Title    The Origin of the Helical Twist Inversion in Single Component Cholesteric Liquid Crystals  
 Abstract    The cholesteric twist inversion by temperature variation o f a single com ponent thermotropic liquid crystalline system was experimentally investigated and is explained by the partial twisting power model, evaluating the temperature dependent pitch o f five different configurations of a benzoic acid biphenyl ester with two chiral centers. The temperature dependence o f the twisting power and the cholesteric pitch for several stereoisomeric com pounds can in first approximation be predicted by the partial twisting powers of the individual chiral centers determined from the partially racemic configurations. 
  Reference    Z. Naturforsch. 49a, 1081—1086 (1994); received August 12 1994 
  Published    1994 
  Keywords    Liquid crystal, Chirality, Cholesteric mesophase, Twist inversion 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1081.pdf 
 Identifier    ZNA-1994-49a-1081 
 Volume    49 
5Author    Dieter Seilmann, Helge Friedrich, Falk KnochRequires cookie*
 Title    Transition Metal Complexes with Sulfur Ligands, XCIX  
 Abstract    Form ation and Structure of [Fe('S4')]4. A Rem arkable Tetram erization of Homochiral [Fe('S4')] Complex Fragments ('S4'2-= l,2-Bis(2-m ercaptophenylthio)ethane(2-)) In MeOH/THF solution, Fe(II) ions and the tetradentate thioether-thiolate 'S4'2"([l,2-Bis(2-mercaptophenylthio)ethane(2-)]) slowly form the tetrameric [Fe('S4')]4 1. The crystal structure of 1 THF -2MeOH was determined by X-ray structure analysis. Chiral 1 crystallizes as a pair of enantiomers each of which consist of four homochiral [Fe('S4')] fragments bridged via /i2-and //3-S(thiolato) donors; stereochemical aspects o f the enantiospecific tetramerization of [Fe('S4')] fragments are discussed. In strong polar solvents such as dimethylformamide, dis­ sociation of [Fe('S4')]4 into [Fe('S4')]2 fragments is indicated by the formation o f [Fe(CO)('S4')]2 upon reaction with CO. 
  Reference    Z. Naturforsch. 48b, 1675—1680 (1993); eingegangen am 9. Juli 1993 
  Published    1993 
  Keywords    Iron Sulfur Complex, Chirality, X-Ray 
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 TEI-XML for    default:Reihe_B/48/ZNB-1993-48b-1675.pdf 
 Identifier    ZNB-1993-48b-1675 
 Volume    48 
6Author    Reiner Memmer, Folkert JanssenRequires cookie*
 Title    Computer Simulation of Chiral Liquid Crystal Phases IX. Chiral Induction in Guest-host Systems - Calculation of the Helical Twisting Power  
 Abstract    The chiral induction in liquid crystalline phases was studied by Monte Carlo simulation of the chiral Lebwohl-Lasher model. Binary guest-host systems composed of achiral and chiral molecules as well as of different chiral molecules were investigated in dependence on the composition. A cholesteric phase was induced by dissolving a small fraction of chiral molecules in a nematic phase. For dilute solutions the equilibrium pitch was found to be a linear function of the chiral dopant concentration. Independent of system size effects the application of self-determined boundary conditions enabled the determination of the symmetry adapted quantities for the chiral induction, the helical twisting power (HTP) and the achiral helical twisting power (AHTP). Additionally, a different orientational behaviour of enantiomer-ic dopants in the chiral surroundings of a cholesteric host phase has been determined. 
  Reference    Z. Naturforsch. 54a, 747—754 (1999); received October 29 1999 
  Published    1999 
  Keywords    Chirality, Liquid Crystals, Computer Simulation, Induced Cholesteric Phases, Helical Twisting Power 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0747.pdf 
 Identifier    ZNA-1999-54a-0747 
 Volume    54