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  • 1
    Electronic Resource
    Electronic Resource
    Approaches for interpreting π electronic states and π electronic transitions (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 235-253 
    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: Scope and limitations of different approaches which enable π electronic systems of topologically equivalent structures to be compared have been examined. Particular attention has been paid to analyses in terms of molecular subsystems.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170207
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  • 2
    Electronic Resource
    Electronic Resource
    MO-LCAO-Calculations on polymethines. V. PPP-type calculations and configuration analyses of simple prototype dyes in terms of molecular subsystems (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 11 (1977), S. 259-269 
    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: In order to elucidate certain controversies in interpreting the π-electronic structure of some simple quinone and indigo dyes the Pariser-Parr-Pople SCβ,γ-wave-functions have been subjected to configuration analyses. Whereas 2,5-diamino-quinone (1) can be excellently represented by coupling of two trimethine-merocyanine chains, the analogous consideration is less appropriate with bispyrrolindigo (2). In this case the results of the configuration analyses indicate clearly the limited applicability of the Longuet/Higgins-Murrell-method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560110206
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  • 3
    Electronic Resource
    Electronic Resource
    MO-LCAO-calculations on polymethines. XIIIPaper XII: J. Fabian, J. prakt. Chem. 322, 1 (1980).. Spectral Effects Resulting from the Cyclization of Cyanine Chains (1981)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 551-560 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO-Berechnungen an Polymethinen. XIII. Spektrale Effekte infolge einer Cyclisierung der PolymethinketteCyclisierung von Streptopolymethinen zu aromatischen oder heterocyclischen Ringen führt entweder zu einer bathochromen oder hypsochromen Verschiebung der Farbbande. Nach PPP-Berechnungen werden die spektralen Effekte durch die Einelektronen-MO-theorie richtig wiedergegeben, ausgenommen einige erste Vertreter der untersuchten vinylogen Reihen. Molekülorbital- und Konfigurationsanalyse stützen die Brauchbarkeit des Polymethinkonzeptes. Das alternative Konzept substituierter Aromaten ist jedoch dann überlegen, wenn spektrale Charakteristika iso-π-elektronischer Strukturen verschiedener Serien verglichen werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19813230404
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  • 4
    Electronic Resource
    Electronic Resource
    MO-LCAO-Berechnungen an Polymethinen. IXVIII. Mitteilung: A. Mehlhorn, J. Sauer, in Vorbereitung. V. und VI. Mitteilung: [1, 2].. Zur Farbigkeit gekoppelter Oxonol- und Cyaninfarbstoffe (1978)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 320 (1978), S. 361-376 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO Calculations on Polymethines. IX. On the Chromaticity of Coupled Oxonol and Cyanine DyesStreptopolymethines display low-energy electronic transitions with a high transition probability and possess, moreover, a high capability to accept or to release electrons. These properties account for the absorption colour of polymethine dyes consisting of two molecular fragments. Scope and limitations of a composite-molecule approach can be recognized by subjecting the electronic wavefunctions to the so-called configuration analysis. Colour-structure relationships are derived from inspection of key orbital interactions between the molecular fragments.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19783200303
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  • 5
    Electronic Resource
    Electronic Resource
    Colour and constitution of organic molecules. J. Griffiths, 1. Aufl., 281 S., 53 Abb., 29 Tab., Academic Press, London/New York/San Francisco 1976. geb., 9, 50£ (1978)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 320 (1978), S. 878-879 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19783200524
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  • 6
    Electronic Resource
    Electronic Resource
    MO-LCAO-Berechnungen an schwefelhaltigen π-Elektronensystemen. L. Synthese und UV/S-spektrale Eigenschaften von 1H-PerimidinthioncarbonsäurederivatenProf. Dr. habil. R. Mayer zum 60. Geburtstag gewidmet (1986)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 812-823 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO Calculations on Sulfur-containing π-Electron Systems. L. Synthesis and UV/VIS Spectral Properties of Derivatives of 1H-Perimidine-2-thioncarbonic AcidEsters of the 1H-perimidine-2-dithiocarbonic acid are easily accessible from 1.8-diamino-naphthalene and chloroacetyl chloride and subsequent thiolation of the reaction product under mild conditions and alkylation. The dithioesters react with aliphatic and aromatic amines to form thioamides. Both the resulting dithioesters and thioamides are clearly distinguished by their colour from the vast majority of known derivatives of thioncarbonic acids. While dithioesters and thioamides are generally red and yellow, respectively, in solution the corresponding derivatives of the 1H-perimidine are blue and red, respectively. The detailed examination of the experimental data has revealed that the colour determining longest wavelength absorption bands are due to the π→π* rather than to the n→π* transitions. Due to the efficient mixing of the lowest energy locally excited (LE) state of the heterocyclic moiety and the lowest energy perimidine-to-substituent charge transfer (CT) state the low-intensity longwavelength π→π* transition of perimidine undergoes a pronounced red shift by acceptor substituents of high electron affinity in 2-position. This interpretation of the deep colour of the 1H-perimidine-2-thiocarbonic acid is in harmony with substituent effects and fully born out by Pariser-Parr-Pople(PPP) type calculations completed by additional analyses of electronic state (Baba-Suzuki-Takemura analysis) and electronic transitions (Ohta-Kuroda-Kunii analysis).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19863280521
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  • 7
    Electronic Resource
    Electronic Resource
    MO-LCAO-calculations on polymethines. XIVPaper XIII: J. FABIAN, J. prakt. Chem. 323, 551 (1981).. Alternative Fragmentation Modes in Describing Benzenoid Chromophores (1981)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 561-570 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO-Berechnungen an Polymethinen. XIV. Alternative Fragmentierung bei der Beschreibung benzoider ChromophoreDie Lichtabsorption donator-acceptor-substituierter Benzene wird allgemein an Hand des Benzenchromophors interpretiert. Ein alternatives Konzept, welches zumindest einen Teil der Verbindungen in die Betrachtung einbezieht, nimmt auf ein Polymethin-Teilchromophor Bezug. Wie durch PPP-Berechnungen (einschließlich Konfigurationsanalyse) an ortho-Aminobenzonitrilen gezeigt wird, führen Donator- wie auch Acceptorsubstituenten in jenen Ringstellungen des ortho-Aminobenzonitrils zu einer bathochromen Verschiebung, die im Heptamethin-Teilchromophor ein gleichartiges Verhalten zeigen. Dieser Befund stützt die Ansicht von DÄHNE, daß sowohl die KAUFFMANNsche wie auch die CALIEZYsche Farbregel durch das Polymethinkonzept verständlich werden.Vorhersagen werden jedoch dann schwierig, wenn Polymethinketten sehr stark in cyclische Strukturen eingeschlossen sind, wie beispielsweise im para-Aminobenzonitril. Dann führen Donator- und Acceptorsubstituenten in beiden freien Ringstellungen zu einer bathochromen Verschiebung. Wie kürzlich für ähnliche Fälle in der Literatur gezeigt wurde, widerspricht dieser Befund auch den DEWAR-KNOTTschen Farbregeln.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19813230405
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  • 8
    Electronic Resource
    Electronic Resource
    MO-LCAO-Calculations on Polymethines. XXIPaper XX: A. MEHLHORN and J. FABIAN, J. Molec. Struct., in press.. Electrono-dative, electrono-captive, and electrono-ambident polymethine radicals (1984)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 326 (1984), S. 443-456 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [N + 1]π-polymethine radicals with nitrogen containing terminal groups (violenes) display electron transfer reactions. Modification of the simple chain structures results in distinct changes of the molecular electronegativity and, consequently, of the redox properties. Based on the formerly defined non-bonding singly occupied MO (SOMO) of ideal polymethines, the various polymethine derivatives are classed into electrono-dative and electrono-captive polymethine radicals. Electrono-dative radicals are prone to release electrons, whereas electrono-captive radicals are prone to accept electrons. This classification reflects experimental results presented by HÜNIG and coworkers, which have been formerly discussed in terms of aromaticity rather than of MO theory. A third class of radicals embraces compounds in which the redox properties of the simple chain polymethine radicals are less changed upon structural modification. These radicals have been termed as electrono-ambident radicals because they are both inclined to release and to accept an electron. HÜNIG and coworkers obviously found the first representatives of this series of radicals. Electronoambident radicals also encounter in VIEHE-type radicals suggesting a more general definition of the latter ones.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19843260313
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  • 9
    Electronic Resource
    Electronic Resource
    MO-LCAO-Berechnungen an schwefelhaltigen π-Elektronensystemen. XLIX. Tetramethinverbrückte Oxalsäurederivate - neue farbige Pigmente von indigoider StrukturProf. Dr. habil. R. Mayer zum 60. Geburtstag gewidmet (1986)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 805-811 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO Calculations on Sulfur-containing π-Electron Systems. XLIX. Tetramethine Bridged Derivatives of the Oxalic Acid - Novel Coloured Pigments of Indigoid StructureWhereas thioamides react with the oxalylchloride to Δ2-thiazoline-4,5-diones 1, which are precursors of the versatile thioacylisocyanate 2 synthons, the analogous reaction between thioamides and oxalyl-bis(arylimidchlorides) completely fails. In the case of aliphatic thioamides the intermediate 2-methyl-Δ2-thiazoline-4,5-diimides 3 undergo oxydative dimerization. The poorly soluble products are tetramethine bridged heteroanalogous oxalates 4 or isomers. The u.v./vis spectra of the blue compounds are in favour with structure 4 rather than with structure 6. This conclusion has been drawn from the results of Pariser-Parr-Pople(PPP) type calculations. According to the calculated position of the colour band of the pigments and of different molecular subunits, and the correspondence of their electronic states involved in the excitation, the dye molecules can be thought as consisting of two symmetrically crossed polymethine chains. This structural feature is inherent to the H indigo chromophore.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19863280520
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  • 10
    Electronic Resource
    Electronic Resource
    Über die Protonierung iso-π-elektronischer Thiotropone (1968)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 37 (1968), S. 41-46 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird die Protonierung der mit Thiotroponen iso-π-elektronischen Trithione (I), Isotrithione (II) und α-Dithiopyrone (III) sowie die Protonierung des Dithiobenzoesäure-methylesters (IV) und der cyclischen Trithiocarbonate (V) in wäßriger Schwefelsäure untersucht. Die H0-Werte der Halbprotonierung werden spektrophotometrisch abgeleitet und die Basizitäten mit den HMO-Elektronendichten verglichen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19680370107
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