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  • Force field calculations  (3)
  • Springer  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Pyrrolpigmente, 42. Mitt. Kraftfeldrechnungen an Gallenfarbstoffen: Die Energiehyperfläche rubinoider Pigmente (1981)
    Springer
    Monatshefte für Chemie 112 (1981), S. 1325-1332 
    Details
    ISSN: 1434-4475
    Keywords: Bilirubin ; Conformational analysis ; Force field calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The energy hypersurface of rubinoid bile pigments is calculated using a force field model previously described. Two cases are observed. I: The pigment is substituted symmetrically or unsymmetrically by apolar groups. This results in a very shallow energy valley containing several enantiomeric conformers of approximately equal energies. II: Substitution by polar groups, especially in position 8 and 12 of the rubin skeleton, (e.g.−CH2−CH2−COOH) is followed by a “lock in” bonding between such groups and the lactam ring functions. Thereby only two enantiomeric conformers, which are energetically stabilized, are possible. The barrier between these species amounts to about 40 kJ/mol. These results are compared with the experimental facts available so far. An analysis of the corresponding energy hypersurfaces of the diastereomeric forms of (Z,Z)-, (E,Z)-, (Z,E)- and (E,E)-configurations is given as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00904684
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  • 2
    Electronic Resource
    Electronic Resource
    Kraftfeldrechnungen an linearen Oligopyrrolen: 2,2′-Bipyrrol, 2,2′-Furylpyrrol und Prodigiosen (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 505-508 
    Details
    ISSN: 1434-4475
    Keywords: 2,2′-Bipyrrole ; 2,2′-Furylpyrrole ; Prodigiosene ; Force field calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using a specific force field model, relative stabilities of 2,2′-bipyrrole and 2,2′-furylpyrrole conformers as well as of prodigiosene tautomers, configurations, and conformations, are studied. 2,2′-Bipyrrole adopts anantiperiplanar conformation in accord with other theoretical calculations and experimental findings. Its rotational barrier calculated by this method compares favourably to the one derived by other means. For the parent prodigiosene the (Z)sp,sp arrangement is found to be the most stable one. The two possible tautomers within its dipyrrin fragment do not show a significant energy difference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810431
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  • 3
    Electronic Resource
    Electronic Resource
    Konformationsanalyse von Gallenfarbstoffen mit Hilfe von Kraftfeldrechnungen (1979)
    Springer
    Monatshefte für Chemie 110 (1979), S. 1025-1027 
    Details
    ISSN: 1434-4475
    Keywords: Bile pigments ; Conformational analysis ; Force field calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A force field constructed for bile pigments and parametrized on partial structures of bile pigments was used to calculate the minimum energy geometries of diastereomeric bilatrienes-abc. In addition the relative energies of these isomers were deduced and the energies of interconversion between the mirror images of the more or less helical (Z,Z,Z)-syn, syn, syn-form were calculated for various paths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00906698
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