Browsing by Author "Kesmarszky, Thomas"

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    Die Acylierung von (Trimethylsilyl)enolethern mit Malonyldichlorid - Darstellung von 4-Hydroxy-2H-pyran-2-onen (Enolether ; 17)
    (1986) Effenberger, Franz; Ziegler, Thomas; Schönwälder, Karl-Heinz; Kesmarszky, Thomas; Bauer, Bernd
    (Trimethylsilyl)enolether von Aldehyden 1 und nichtcyclischen bzw. cyclischen Ketonen 4 bzw. 10 lassen sich mit Malonyldichlorid bei Raumtemperatur bzw. bereits bei -60°C acylieren. Hierbei entstehen nach wäßriger Aufarbeitung aus den 1-(Trimethylsiloxy)alkenen 1 die bislang nur schwer zugänglichen 6-unsubstituierten 4-Hydroxy-2H-pyran-2-one 3 und aus den 1-(Trimethylsiloxy)cycloalkenen 10 die 5,6-Alkylen-überbrückten 4-Hydroxy-2H-pyran-2-one 11. Die Acylierung von 2-(Trimethylsiloxy)-1-propen (4a) und 3-(Trimethyl-siloxy)-2-penten (4b) führt zu Gemischen aus 4-(Trimethylsiloxy)-2H-pyran-2-onen 5 (Hauptprodukte) und Phloroglucin-tris(trimethylsilylethern) 6 (Nebenprodukte).
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    Intramolecular energy transfer through linear polyenes : effect of spacers
    (1990) Blessing, Gerd; Holl, Norbert; Port, Helmut; Wolf, Hans Christoph; Effenberger, Franz; Kesmarszky, Thomas; Schlosser, Hubert
    The optical properties of linear polyenes terminally substituted with different molecules (mainly anthryl- and TPP-substituents) have been studied. Bicyclic spacers within the polyene chain affect the quantum yields but do not interrupt intramolecular energy transfer between the endgroups.
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    Lowest excited singlet states of α-9-anthrylpolyenes
    (1993) Holl, Norbert; Emele, Peter; Port, Helmut; Wolf, Hans Christoph; Strobel, Hartmut; Kesmarszky, Thomas; Effenberger, Franz
    Properties of the electronically excited states of α-9-anthrylpolyenes are studied in n-hexane solutions by using optical absorption, emission and fluorescence excitation spectroscopy. The absorption spectra reveal a complex structure with contributions of both anthracene and polyene type bands but also of bands with mixed anthracence/polyene character. Small amounts of remaining impurities are chemically not separable but can be detected via fluorescence measurements. By computer-aided decomposition of spectra measured under variable selective excitation the actual, clearly chain-length dependent, fluorescences could be obtained.
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    Synthese und optische Eigenschaften endständig substituierter konjugierter Polyene mit Bicyclo[2.2.2]octan als Spacer
    (1992) Effenberger, Franz; Kesmarszky, Thomas
    The conjugated polyenes 10, 11, and 17 respectively, with 9-anthryl- and 2-tetraphenylporphyrinyl (TPP) terminal groups and a bicyclooctane unit incorporated into the polyene chain were synthesized by Wittig olefinations. In all cases it was possible to obtain the all-(E) compounds from the (E)/(Z)-isomeric mixtures by chromatographic purification and several recrystallizations. From the UV/Vis spectra the separation of the TPP group and the polyene chain in 10, 11, and 17 can be deduced whereas in 10 and 11 the two conjugated double bonds are amalgamated into the anthryl group. In 17 the anthryl group is electronically separated from the polyene chain, and a selective excitation therefore is possible.