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  • 1
    Electronic Resource
    Electronic Resource
    Charge-Transfer-Komplexe mit Polymeren aus substituierten Spirocyclopropan-1.9′-fluoren-Verbindungen. 1. Mitt. Modellverbindungen und Oligomere (1971)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 146 (1971), S. 195-205 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Complex formation, ε-values and stoichiometry of charge-transfer complexes of TCNE and TCNQ respectively with substituted spiro-cyclopropane-1.9′-fluorene derivatives as well as with a dimer and a oligoester of the same type have been determined. In general, TCNQ complexes show CT-bands at longer wavelengths than TCNE complexes. TCNE-complexes of the cis-isomers have been proven to be more stable than those of the trans-isomers.
    Notes: Komplexbildungskonstanten, molare Extinktionskoeffizienten und Stöchiometrie der CT-Komplexe von Tetracyanäthylen (TCNE) und Tetracyanchinodimethan (TCNQ) mit substituierten Spirocyclopropan-1.9′-fluoren-Verbindungen sowie mit einem Dimeren und einem Oligoester wurden mittels spektroskopischer Methoden bestimmt. Die TCNQ-Komplexe haben längerwellige CT-Banden als die TCNE-Komplexe. Die TCNE-Komplexe der cis-Isomeren sind stabiler als die der trans-Isomeren.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1971.021460120
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  • 2
    Electronic Resource
    Electronic Resource
    Radikalionenbildung in Lösungen von TCNQ und Polyvinylalkoholacetalen von Naphthalinaldehyd (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1369-1372 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790527
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of Self-Assembly of Amphiphilic Redox-Chromophores on Photoionization Processes (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2036-2047 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A surfact derivative of phenothiazine was synthesized which is capable of micelle formation in aqueous solution. Concomitantly with micellization, strong changes in the photochemical behaviour occur. In particular, monophotonic photoionization is only observed above the critical micelle concentration (CMC.). Cooperative effects associated with self-assembly of this amphiphilic redox chromophore leading to local electrostatic barriers are evoked to explain these effects.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640708
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  • 4
    Electronic Resource
    Electronic Resource
    Singlet Oxygen and Superoxide: Experimental Differentiation and Analysis (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 722-733 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Superoxide produced by either pulse radiolysis or from KO2 undergoes no reaction with furfuryl alcohol competitive to the corresponding endo-peroxide formation with singlet oxygen. Thus, furfuryl alcohol can be used as a specific chemical quencher of singlet oxygen.Superoxide can be quantitatively analyzed by its electron transfer reaction with 1, 4-benzoquinone.The differentiation of the two activated species of oxygen has been realized in microemulsions. Singlet oxygen is known to penetrate the interfaces of surfactant aggregates and may be analyzed in the hydrophobic core by known methods. Charged surfaces on such aggregates, specially those formed by anionic surfactants, prevent the passage of superoxide and restrict its presence and the need for analysis to the bulk aqueous phase.Hydrated electrons may penetrate the interface depending on the dose per pulse applied. 2, 5-Di (t-butyl)-1, 4-benzoquinone has been taken as an acceptor for electron transfer reactions within the hydrophobic core.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660236
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  • 5
    Electronic Resource
    Electronic Resource
    The Formulation of Four-Components Practically Perfluorinated Microemulsions (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 1183-1188 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microheterogeneous systems consisting of sodium perfluorooctanoate (1), 2, 2, 3, 3, 4, 4, 4-heptafluoro-1-butanol (2), perfluorohexane (3) and water, representing the first practically perfluorinated microemulsions based on ionic surfactants have been formulated. A pseudoternary phase diagram shows a central region of turbid or transparent gels and two regions of monophasic systems (O/W- and W/O-microemulsions) which have been characterized by NMR. spectroscopy.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660420
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  • 6
    Electronic Resource
    Electronic Resource
    Singlet-Oxygen Quenching by Carotenoids: Steady-state luminescence experiments (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1005-1010 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The near-infrared luminescence of singlet oxygen (1O2) has been measured in order to determine the efficiency of 1O2 quenching by two carotenoid compounds, β-carotene and canthaxanthin. 1H-Phenalen-1-one and rose bengal have been used as photosensitizers in those steady-state luminescence experiments. Stern-Volmer analysis of the 1O2 luminescence in solutions of CCl4 and CD3OD, containing different concentrations of the carotenoids, has shown a very efficient quenching by canthaxanthin. The rate constants are about a factor of 2 below the diffusion limited values for the given solvents, confirming earlier results in benzene. In comparison, the efficiency of 1O2 quenching by β-carotene is slightly lower than that by canthaxanthin in non-polar solvents and is reduced by an order of magnitude in CD3OD, due to the aggregation of this quencher.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710510
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  • 7
    Electronic Resource
    Electronic Resource
    Laser Flash Photolysis of Phthalocyanines in Solution and Microemulsion (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1800-1806 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triplet state formation (Φisc) and properties (εT-T, τT) of phthalocyanine (HPC) and zinc phthalocyanine (ZnPC) have been characterized in homogeneous solutions (1-chloronaphthalene, 1-propanol) and in microemulsion by investigating the variation of the transient optical density as a function of the intensity of the exciting laser. Experimental results follow the theoretically predicted dependence only for very low intensities of the exciting pulse. At higher intensities, a more complicated scheme of primary reactions has to be taken into account, implicating qualitative restrictions in the application of saturation experiments. The observed transients at high-intensity excitation are interpreted as being perturbed by aggregational phenomena.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640610
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of the Quantum Yield of Intersystem Crossing of Rose Bengal (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1760-1773 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (ϕet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · ϕet = Φ(1O2), with ϕet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700712
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  • 9
    Electronic Resource
    Electronic Resource
    Solvent Isotope Effect on the Rate Constants of Singlet-Oxygen Quenching by edta and Its Metal Complexes (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 859-868 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactivity of singlet oxygen (O2(1Δg)) with edta and its metal complexes with Al3+, Cu2+, Fe3+, and Mn2+ was investigated. The emission of singlet oxygen at 1270 nm in D2O was measured in order to determine the quenching efficiency of edta and edta-metal complexes for different metal/edta ratios. The sum of the rate constant (kr + kq) of the chemical reaction between singlet oxygen and the acceptor (kr) and of the physical quenching of singlet oxygen by the acceptor (kq) was obtained by a Stern-Volmer analysis. Measurements of the oxygen consumption in H2O were used to determine quantum yields of the sensitized photooxidation, and the combined results of these experiments allowed the determination of kr and kq separately. A strong isotope effect was observed between the deuterated and the hydrogenated solvents. This effect was shown to be independent of the analytical procedure used. The isotope effect, as well as the reactivity of edta and its metal complexes, depend markedly on the complexed metal ion.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770325
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  • 10
    Electronic Resource
    Electronic Resource
    Zum Mechanismus der Photoreduktion von Wasser mit Ruthenium-trisbipyrazil als Sensibilisator (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2652-2655 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Mechanism of the Photoreduction of Water with Ruthenium-trisbipyrazil as SensitizerOxidative and reductive primary steps can be differentiated in using Ru(bipy)32+ and Ru(bipz)32+, respectively, as sensitizers in a photochemically induced, Pt-catalyzed sacrificial water reduction. Experimental evidence for the reductive primary step and kinetic data are given for the electron transfer to methylviologen as relay compound.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660833
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