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Verfasst von:Jiang, Man [VerfasserIn]   i
 Paul, Nicholas [VerfasserIn]   i
 Buckup, Tiago [VerfasserIn]   i
 Motzkus, Marcus [VerfasserIn]   i
Titel:Photocleavage of coumarin dimers studied by femtosecond UV transient absorption spectroscopy
Verf.angabe:Man Jiang, Nicholas Paul, Nikolai Bieniek, Tiago Buckup, Norbert Hampp, Marcus Motzkus
E-Jahr:2017
Jahr:18 January 2017
Umfang:10 S.
Fussnoten:Published on 18 January 2017 ; Gesehen am 27.08.2018
Titel Quelle:Enthalten in: Physical chemistry, chemical physics
Ort Quelle:Cambridge : RSC Publ., 1999
Jahr Quelle:2017
Band/Heft Quelle:19(2017), 6, Seite 4597-4606
ISSN Quelle:1463-9084
Abstract:Coumarins are a class of UV absorbing compounds which exhibit fast, photoinduced cyclobutane ring formation and cleavage reactions. The photophysics behind such processes hold significant relevance for biomedical and photoresponsive materials research. In order to further understand the underlying dynamics of the cleavage reaction, and develop strategies for increasing the reaction efficiency, UV transient absorption spectroscopy was applied to three unsubstituted, isomeric coumarin dimers: anti-head-to-head (anti-hh), syn-head-to-head (syn-hh) and syn-head-to-tail (syn-ht). The experiments performed under 280 nm excitation and broadband (300-620 nm) probing revealed that the cleavage reaction of coumarin dimers occurs through non-radiative, short-lived (<200 fs) singlet states. From the data, two branched kinetic models were developed to describe the monomer formation and dimer relaxation dynamics, identify possible intermediate states, and determine the quantum yields of the dimer cleavage. The anti-hh dimer shows the highest cleavage efficiency with a value of about 20%. The differences in the cleavage efficiency for the three isomers are interpreted in terms of differing steric hindrances of the benzene groups attached to the cyclobutane ring and charge delocalisation of the intermediate state.
DOI:doi:10.1039/C6CP08076F
URL:Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.

Volltext ; Verlag ; Resolving-System: https://pubs.rsc.org/en/content/articlelanding/2017/cp/c6cp08076f
 Volltext: http://dx.doi.org/10.1039/C6CP08076F
 DOI: https://doi.org/10.1039/C6CP08076F
Datenträger:Online-Ressource
Sprache:eng
K10plus-PPN:1580402240
Verknüpfungen:→ Zeitschrift

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