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  • 11
    Electronic Resource
    Electronic Resource
    Electronic states of benzo[a]pyrene. Linear and magnetic circular dichroism, polarized fluorescence, and quantum chemical calculations (1992)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 114 (1992), S. 1942-1949 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00032a003
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  • 12
    Electronic Resource
    Electronic Resource
    The alternant hydrocarbon pairing theorem and all-valence electrons theory. An approximate LCOAO theory for the electronic absorption and MCD spectra of conjugated organic compounds, part 2 (1997)
    Springer
    Theoretical chemistry accounts 98 (1997), S. 137-153 
    Details
    ISSN: 1432-2234
    Keywords: Key words: All-valence electrons MO theory ; AO orthogonalization effects ; Alternant hydrocarbon pairing symmetry ; Electronic transitions ; Magnetic circular dichroism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. An approximate linear combination of orthogonalized atomic orbitals (LCOAO) all-valence electrons theory is described, based on a previously suggested partitioning of the Fock operator. Kinetic energy and penetration terms are evaluated explicitly in a Löwdin OAO basis, while two-electron repulsion terms are treated according to the conventional neglect of differential overlap (NDO) approximation. One-electron and penetration integrals are parameterized explicitly to predict approximate alternant pairing symmetry for the π-systems of benzene and napthalene. Application of the resulting LCOAO theory to a variety of alternant and non-alternant hydrocarbons demonstrates significant improvements in the prediction of MCD B-terms and transition moment directions, particularly for alternant (4N+2)- or 4N-perimeter π-systems for which traditional NDO procedures fail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002140050287
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  • 13
    Electronic Resource
    Electronic Resource
    Orbital interactions in anti- and syn- tricyclooctadienes and their homoderivatives (1978)
    Springer
    Theoretical chemistry accounts 50 (1978), S. 145-158 
    Details
    ISSN: 1432-2234
    Keywords: Tricyclooctadienes, PE spectra and MO calculations of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photoelectron spectroscopy and molecular orbital calculations of the Extended Hückel, MINDO/3 and STO-3G Hartree-Fock type have been applied to anti- and syn-tricyclo[4.2.0.02,5]octadiene (1 and 2) and their homo and bishomo derivatives. The resulting ordering of the one-electron levels for 1 and 2 are 7a g (π +), [6b u (σ), 5b u (π−)], 4a u (σ), 3a u (σ) and 7a 1(π+), 5b 2(σ), 6b 2(π−), 3a 2(σ), 4b 1(σ), respectively. The present results differ substantially from those previously published.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00550187
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  • 14
    Electronic Resource
    Electronic Resource
    Structure and solvation of nitrobenzene and 1,4-dinitrobenzene radical anions (1979)
    Springer
    Theoretical chemistry accounts 51 (1979), S. 65-78 
    Details
    ISSN: 1432-2234
    Keywords: INDO method with inclusion of an effective solvent field ; Nitrobenzene ; 1,4-dinitrobenzene radical anions, spin distribution and geometries of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An INDO method extended to include a contribution from the solvent by means of an effective solvent field (INDO-ESF) and based on properly optimized geometries is applied to the nitrobenzene and 1,4-dinitrobenzene radical anions. The hyperfine couplings and their solvent sensitivities are reproduced within a planar structure of the radicals. The behaviour of14N and17O splittings in derivatives with twisted nitro groups is accounted for with no difficulty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554232
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  • 15
    Electronic Resource
    Electronic Resource
    Structure and solvation of nitrobenzene and 1,4-dinitrobenzene radical anions (1979)
    Springer
    Theoretical chemistry accounts 51 (1979), S. 65-78 
    Details
    ISSN: 1432-2234
    Keywords: INDO method with inclusion of an effective solvent field ; Nitrobenzene ; 1,4-dinitrobenzene radical anions, spin distribution and geometries of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An INDO method extended to include a contribution from the solvent by means of an effective solvent field (INDO-ESF) and based on properly optimized geometries is applied to the nitrobenzene and 1,4-dinitrobenzene radical anions. The hyperfine couplings and their solvent sensitivities are reproduced within a planar structure of the radicals. The behaviour of14N and17O splittings in derivatives with twisted nitro groups is accounted for with no difficulty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399131
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  • 16
    Electronic Resource
    Electronic Resource
    INDO Calculations with inclusion of an effective solvent field. Application to benzosemiquinones (1978)
    Springer
    Theoretical chemistry accounts 47 (1978), S. 315-328 
    Details
    ISSN: 1432-2234
    Keywords: INDO method with a contribution from the solvent ; Benzosemiquinones, spin densities and geometries of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An INDO method extended to include a contribution from the solvent by means of an effective solvent field (ESF) is applied to the three isomeric benzosemiquinones and some of their alkyl derivatives. The calculations lead to a satisfactory description of the hyperfine coupling constants, in contrast to traditional calculations. The results imply that the spin distribution in p- and o-semiquinones is largely determined by the influence of the solvent; in particular, the influence is able to invert the order of the spin densities at the 3 and 4 positions in 1,2-benzosemiquinone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549261
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  • 17
    Electronic Resource
    Electronic Resource
    Electronic states of the [2 n ]cyclophanes (1983)
    Springer
    Theoretical chemistry accounts 64 (1983), S. 187-203 
    Details
    ISSN: 1432-2234
    Keywords: [2 n ]Cyclophanes ; Excited states of∼ ; Through-bond and through-space interactions in ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Low energy singlet and triplet states for a series of [2 n ]cyclophanes are discussed in terms of the results of a simple model calculation. Experimental trends can be explained under the assumption of significant σ-π interaction involving the saturated bridges. This interaction destabilizes low energy “excimer” states, in contrast to the usual red shift observed for alkylbenzenes. The observed near-constancy of the onset of the absorption spectra can be explained by near-cancelation of through-bond and through-space contributions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00551396
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  • 18
    Electronic Resource
    Electronic Resource
    On bridging the gap between extended Hückel and NDO Type LCAO-MO theories (1980)
    Springer
    Theoretical chemistry accounts 55 (1980), S. 165-172 
    Details
    ISSN: 1432-2234
    Keywords: Orthogonalization effects in NDO theories ; representation of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The possibility of incorporating overlap effects as well as electron interaction terms in simple LCAO-MO theories is discussed. A recent suggestion by de Bruijn is criticized and a revised scheme is developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576960
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  • 19
    Electronic Resource
    Electronic Resource
    The molecular and electronic structure of dibenzo[g,p]chrysene: A twisted case (1994)
    Springer
    Theoretical chemistry accounts 89 (1994), S. 301-309 
    Details
    ISSN: 1432-2234
    Keywords: Transition moments ; Linear dichroism ; Dibenzo[g,p]chrysene, conformation and UV spectra of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Studies of the electronic structure and spectrum of dibenzo [g,p]chrysene, carried out in 1965 and 1985, were not fully conclusive. They are repeated here by means of improved linear dichroism spectroscopy, quantum mechanical calculations of the spectra, and structural studies. Based on the new evidence, especially the observed transition moment directions, it is concluded that the molecule is nonplanar with D2 symmetry. The experimentally determined transition moment directions also allow a complete assignment of all significant transitions in the region 25 000 to 45 000 cm−1. All three possible (perpendicular) transition moment directions are represented among the observed electronic transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01114103
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  • 20
    Electronic Resource
    Electronic Resource
    Electronic States of Phenylene and Naphthylene Bicyclobutanes. Linear Dichroism in Stretched Polyethylene (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 676-686 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Excited singlet states of bicyclobutylene-benzene (2), 1,2:4,5-bis (bicyclo-butylene)benzene (3), 2,3-bicyclobutylene-naphthalene (4), and 1,8-bicyclobutylene-naphthalene (5) are investigated by means of linear dichroic absorption spectroscopy of molecules oriented in stretched polyethylene films and by semiempirical model calculations. The results indicate a strong hyperconjugative impact of the bicyclobutylene group on the aromatic chromophores in these compounds. Valence isomerization to aromatic products is predicted as the preferred photochemical pathway.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660231
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