Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Atomic, Molecular and Optical Physics  (2)
  • Polymer and Materials Science  (2)
  • 1
    Electronic Resource
    Electronic Resource
    A multi-configuration LCAO-MO study for complex unsaturated molecules. I. General theory and its application to the benzene anionThe material in this paper is taken from a thesis submitted by M. Nakayama in partial fulfilment of the requirements for the doctor's degree at Tokyo Kyoiku University. (1970)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 4 (1970), S. 21-42 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multi-configuration LCAO-MO approach using a π-bond order-bond length linear relation is introduced to predict the geometrical structures for the electronic ground and excited states of unsaturated hydrocarbons. The procedure is designed to include configuration interaction in each iterative computation where the π-electron approximation is employed under the Pariser-Parr type semi-empirical treatment.The π-bond order-bond length relation is determined as rpq = 1.523 - 0.193Ppq, when the bond lengths of ethylene, benzene and naphthalene are used and the groundstate functions including the singly and doubly excited configurations are taken into account to obtain the bond orders Ppq.The iterative calculation is applied to the ground state and the two lowest excited states of the benzene anion in both D6h and D2h molecular geometries. The geometrical structures and the π-electron energies are computed for the ground and excited states of the anion; for the latter, two types of configuration species are used. It is found that the first lowest excited state is not subjected to the Jahn-Teller effect and the calculated excited state energies do not agree with the observed values (c. 1.0 ∼ 2.5 eV higher than the observed values). The latter point is discussed in detail. It is also found that the resultant ground state energy depression due to configuration mixing is not very large and the two types of configuration species used give different CI effects on the energy levels of the two lowest excited states of the anion.Finally, the stabilization energy due to the Jahn-Teller distortion is estimated for the ground state of the anion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560040104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A multi-configuration LCAO-MO study for complex unsaturated molecules. II. Application to the benzene cationThe material in this paper is taken from a thesis submitted by M. Nakayama in partial fulfilment of the requirements for the doctor's degree at Tokyo Kyoiku University. (1970)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 4 (1970), S. 43-55 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of the MC-LCAO-MO approach, described in the preceding paper, is further applied to the benzene cation. Through the iteration process the π-electron energies and the molecular shapes are computed for the ground and two lowest excited states of the cation in both D6h and D2h geometries. A remarkable fact obtained is that a comparatively small variation of the geometrical structure (c. 0.010 - 0.013 Å bond length difference) brings about a considerable change of the energy value (c. 0.85 - 1.25 eV).The π-electronic excitation energies obtained from the iteration process are compared with the transition energies calculated from the usual method in which the structures of the excited states are assumed to be the same as the corresponding ground state structures. The difference in the excitation energy between the cation and the anion, and the CI effect on the excited states, are discussed. It is found that the doubly excited configurations play an important role in CI, which is somewhat different from that of the singly excited configurations. The stabilization energy due to the Jahn-Teller distortion is estimated for the ground state of the cation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560040105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and separation characteristics of strongly basic anion-exchange resins prepared from different monomers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 517-522 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Chloromethylstyrene-ethylene glycol dimethacrylate (EGDMA) copolymer beads (PCMS) and dimethylaminomethylstyrene-EGDMA copolymer (PDAMS) were synthesized by suspension polymerization as noble polymer matrices. The chemical and physical properties of the quaternized resins (PCMS-Q and PDAMS-Q) were approximately equal. The characteristics of both resins were examined by high-performance liquid chromatography using columns packed with the resins. These resins served as conventional anion-exchange resins for small organic anions, but indicated markedly different retention for large molecular anions, namely, PDAMS-Q retained proteins having a negative net charge, but PCMS-Q did not. It was suggested that the chemical and physical structures on the external surfaces of ion exchangers are very important in ion-exchange chromatography of proteins.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460318
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Molecular and crystal structures of Aib-containing oligopeptides Boc-Leu4-Aib-Leu4-OBzl and Boc-(Leu4-Aib)2-OBzl (1991)
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 975-985 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sample peptides Boc-Leu4-Aib-Leu4-OBzl and Boc-(Leu4-Aib)2-OBzl, were crystallized by the solvent-evaporation method. Both crystals are monoclinic, with space group of P21 and Z = 2. The cell parameters are a = 16.580(7), b = 21.105(7), c = 11.583(4) Å, and β = 104.90(3)° (Boc-Leu4-Aib-Leu4-OBzl), and a = 15.247(9), b = 19.04(l), c = 16.311(9) Å, and β = 117.10(1)° [Boc-(Leu4-Aib)2-OBzl]. Crystal structures were solved by the direct method and refined to R values of 0.096 (the former peptide) and 0.112 (the latter). Peptide backbones fold into a right-handed α-helix, except for the C-terminal Aib residue in Boc-(Leu4-Aib)2-OBzl. Both peptide molecules are stabilized by six (the former) or seven (the latter) intramolecular (5 → 1) hydrogen bonds, and arranged in the head-to-tail fashion, which makes an infinite column. In this column, one (the former) or two (the latter) intermolecular hydrogen bonds link the neighboring molecules. In the case of Boc-Leu4-Aib-Leu4-OBzl, the solvent molecule N, N-dimethylformamide was found in the difference Fourier map. There was a hydrogen bond between peptide and solvent molecule. Along the lateral direction, only hydrophobic contacts were observed between adjacent peptide molecules.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360310807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...