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  • 1985-1989  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Lösungsmittel-, Viskositäts-, Säure- und Substituenteneinflüsse auf die Photoisomerisierung und Relaxation symmetrischer Triazacarbocyanine bei 283 bis 323 K (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1401-1405 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influence of Solvents, Viscosity, Acid, and Substituents on the Photoisomerization and the Relaxation of Symmetrical Triazacarbocyanine Dyes at 283 to 323 KPhotobleaching and the reverse dark reaction of seven symmetrical triazacarbocyanine dyes with different heterocycles were studied dependent on solvent effects (protic and aprotic solvents), on effects of viscosity (glycerol/EtOH mixtures), and on effects of added acid. No effects of dissolved O2 or added I2 has been observed. Kinetic data (ΔH≠, ΔS≠, and ΔG298 K≠) of the reverse reaction are given. The effect of the substituents has been studied on two series of substituted triazacarbocyanine dyes. The mechanism of the reverse reaction is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680532
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Photoisomerisierung und Relaxation symmetrischer Triazacarbocyanine in einem Alkoholgemisch (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1394-1400 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoisomerization and Relaxation of Symmetrical Triazacarbocyanine Dyes in an Alcoholic Mixture at Low TemperatureThe partial photobleaching of a series of symmetrical triazacarbocyanine dyes with different heterocycles in EtOH/MeOH/i-PrOH at low temperature (110 to 250 K) was investigated by UV/VIS spectra. Kinetic data of the dark reaction of photobleached compounds are given. The effect of electron-donating or -accepting substituents, respectively, and of protonation of the photobleached compound on kinetic data and on UV/VIS spectra was studied. Products of photobleaching and mechanisms of the dark reaction are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680531
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Tetrazinodi(heteroarene): Voltammetrische und cyclovoltammetrische Untersuchung der Oxidation in Methanol, Acetonitril und Dichlormethan (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1531-1534 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazinodi(heteroarenes): Voltammetric and Cyclovoltammetric Studies of the Oxidation in Methanol, Acetonitrile, and DichloromethaneThe oxidation of seven symmetrical [1,2,4,5]tetrazinodi(heteroarenes) with different heterocycles has been investigated by means of dc, ac, and cyclic triangular voltammetry in MeCN and CH2Cl2 (containing Bu4NClO4), MeOH (containing LiCl) and in MeOH/H2O (equimolar mixture). The two step oxidation mechanism has been found of type ‘e-e’ with quasi-reversible electrochemical steps. Oxidation potentials and transfer coefficients have been measured (0 to +0.5 V vs. Ag/AgCl/3.5M KCl for the first oxidation step and potential differences of 0.8 to 1.3 V to the second oxidation step), indicating a high radical-ion stability.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690625
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Thermochromie von Heterospiranen und Farbbildnern mit heterocyclischen Teilsystemen und O oder N als Ringschlussatom (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 1583-1589 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on the Thermochromism of a Series of Spirocyclic Compounds and ‘Colourformers’ with Heterocyclic Parts and O or N as the ‘Key’ Atom.The thermochromism of a series of spirocyclic compounds with heterocyclic parts and O or N as the ‘key’ atom and of ‘colourformers’ was investigated in different solvents such as benzyl alcohol, dimethyl phthalate, decaline, toluence, or xylene. Thermodynamic data for the involed equilibria (ΔH°, ΔS°, and ΔG°298k) and VIS-spectroscopic data were determined and discussed in relation to the ones known spiropyrances. Compounds with O as ‘key’ atom behave very similary to the known spiropyrances, compounds with N as ‘key’ atom mostly are unstable undergoing irreversible bleaching. The ‘colour formers’ usually show only small thermochromic effects and very small equilibrium concentration of the coloured form.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720718
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    Paper (German National Licenses)
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