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  • Analytical Chemistry and Spectroscopy  (4)
  • luminescence  (1)
  • 1
    ISSN: 1573-9171
    Keywords: spironaphthoxazine ; open form ; lifetime ; activation energy ; absorption spectrum ; luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The insertion of benzo-15-crown-5 or benzo-18-crown-6 as a substituent at the 9'-position of a spironaphthoxazine molecule increases the lifetime of the open form of spironaphthoxazine by a factor ofca. 2. The complex formation between the crown groups and Mg2+ or Ba2+ ions changes the lifetime slightly. The addition of benzo-18-crown-6 at the 5'-position leads to an increase in the lifetime of the open form by an order of magnitude and the appearance of absorption with a maximum at 16420 cm−1 under dark conditions, which testifies to the stabilization of the open form. The addition of Ba2+ ions to this compound results in a further increase in the lifetime byca. 35% due to complex formation. The luminescence of the benzo-15-crown-5-substituted compound is probably caused by both the complexation with Mg2+ and the photochemical reaction induced by photoactive light and is accompanied by the irreversible loss of photochromism.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 493-498 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A series of α-oxobenzimidazolinic merocyanines differently substituted on the ‘phenolate’ part and bearing a paraffinic chain on one heterocyclic nitrogen, has been studied by 13C NMR. Electron donating substituents bring about an increase of the electronic density on the 3 methine carbon and an increase of the alternation of electron density on the 3,4-dimethine bridge. A bathochromic shift of the lower energy electronic transition is also observed. Furthermore, the low field resonance of the 3 methine proton is probably due to a specific interaction between this proton and the ‘phenolate’ oxygen atom. This implies the existence of a favoured trans configuration for merocyanine dyes.
    Notes: Une série de mérocyanines α-oxo benzimidazoliniques diversement substituées sur la partie ‘phénolate’ et possédant une chaǐne grasse sur l'un des azotes hétérocycliques, a été étudiée en RMN du carbone- 13. Des substituants donneurs d'électrons provoquent une augmentation de la densité électronique sur le carbone méthinique C-3 et une augmentation de l'alternance de la distribution de charge sur le pont diméthinique 3,4. Corrélativement un déplacement bathochrome de la transition électronique de plus basse énergie est observé. Par ailleurs, l'apparition de la résonance à champ faible du proton méthinique H-3 semble due à une interaction spécifique intervenant entre ce proton et l'atome d'oxygène ‘phénolate’, ce qui suppose l'existence d'une configuration trans privilégiée pour les mérocyanines.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 10 (1977), S. 39-42 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A 13C n.m.r. study of different heterocyclic spiropyrans has been carried out. We have attempted to describe the specific influence of the heteroatoms on the chemical shift of the neighbouring atoms. Carbon-13 chemical shifts and coupling constants have been also obtained for compounds similar to both parts of the spiropyran molecule: the heterocycle and the benzopyran.
    Notes: Une étude en RMN du carbone-13 d'une série de spiropyrannes qui diffèrent par leur partie hétérocyclique a été réalisée. Nous avons tenté d'évaluer l'influence spécifique des divers hétéroatomes sur le déplacement chimique des atomes voisins. Les déplacements chimiques et les constantes de couplage J(CH) ont également été déterminés pour les composés analogues à chacune des deux parties constitutives de la molécule de spiropyranne: hétérocycle et benzopyranne.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 62-73 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzothiazolinic spiropyrans, merocyanines and photomerocyanines, thermally stabilised to a high degree, have been studied by means of Fourier transform 1H and 13C NMR. The results show the polarity of open forms such as merocyanines and photomerocyanines, their trans configuration, the alternation of the electronic density on the dimethine bridge between the ‘benzothiazolinic’ and ‘phenolate’ part of these molecules, and also a favoured configuration when photomerocyanines have an alkoxy or aryloxy group on the 3 position.
    Notes: Une étude comparative en RMN 13C et 1H par transformée de Fourier a été réalisée sur des spiropyrannes, des mérocyanines et des photomérocyanines hautement stabilisées thermiquement, en série benzothiazolinique. Les résultats obtenus mettent en évidence la polarité des formes ouvertes (mérocyanines et photomérocyanines stables), de façon générale leur configuration trans, la répartition alternée des densités électroniques sur le pont diméthinique reliant les parties ‘benzothiazolinique’ et ‘phénolate’ de ces molécules, l'existence d'une configuration privilégiée dans le cas de photomérocyanines où un groupement alkoxy ou aryloxy occupe la position 3.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 137-138 
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thirty two-linked macrocycle models of natural ionophorus nactin antibiotics were studied by 13C NMR spectroscopy and their chemical shifts are reported.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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