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  • crystal engineering  (1)
  • electrostatic potentials  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Urea-glutaric acid (2∶1) structural aggregates as building blocks for crystal engineering (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 823-829 
    Details
    ISSN: 1572-8854
    Keywords: Urea-glutaric acid complex ; structural building block ; molecular recognition ; solid state organization ; crystal engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of a 2∶1 urea-glutaric acid cocrystal has been determined. The crystal is monoclinic:C2lc,a=11.954(5),b=10.932(1),c=9.078(3) Å, β=97.86(3)°, withZ=4. The formula unit is a hydrogen-bonded heterotrimeric aggregate consisting of one acid subunit locked between two identical urea subunits. The symmetric arrangement from both sides of the acid allows for retaining the twofold axis primary inherent for the glutaric acid. An additional symmetry element (inversion center) is introduced during the aggregate self-association into one-dimensional chains, which are further organized through glide operations into a well-defined three-dimensional, hydrogen-bonded crystal network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01671077
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  • 2
    Electronic Resource
    Electronic Resource
    A computational analysis of some diaryl ureas in relation to their observed crystalline hydrogen bonding patterns (1991)
    Springer
    Molecular engineering 1 (1991), S. 75-87 
    Details
    ISSN: 1572-8951
    Keywords: Diaryl ureas ; electrostatic potentials ; hydrogen bond patterns ; cocrystal selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We have carried out anab initio self-consistent-field molecular orbital analysis of the structures, atomic charges and electrostatic potentials of 1,3-bisphenylurea, 1,3-bis(m-nitrophenyl)urea and 1,3-bis(p-nitrophenyl)urea. Our results provide insight into the contrasting hydrogen bond patterns and preferences of these molecules in crystalline environments. The tendency for 1,3-bisphenylurea to form homomeric rather than heteromeric (i.e. host-guest) crystals is attributed to a relatively strong and extended homomeric attractive electrostatic interaction between two like molecules. Our calculated internuclear distances and atomic charges indicate that these molecules have some degree of H...O intramolecular hydrogen bonding between the carbonyl oxygen and the nearest aromatic hydrogens when the aromatic and the urea portions of the molecules are coplanar. This interaction is strongest for the meta nitro derivative, consistent with the latter remaining very nearly planar in its cocrystal structures. Our surface electrostatic potentials for the three diaryl ureas are used to interpret their differing crystallization properties and tendencies to form cocrystals with guest molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00625739
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