TY  - JOUR
A1  - Schmidt, Reinhard
T1  - The endoperoxide of tetrabenzopentancene. A new photochromic endoperoxide
T2  - Zeitschrift für Naturforschung, A
N2  - The thermal and the photochemical reactions of the endoperoxide of Tetrabenzo(bc,fg.lm,pq)- pentacene have been investigated with respect to its photochromic properties. The thermal yield of irreversible rearrangement reactions was determined to be Adec = 0.045. From the activation parameters of the thermal cycloreversion. forming the parent hydrocarbon and oxygen, a half life time of 114 years at 20 °C has been extrapolated. For the quantum yield of the irreversible photochemical rearrangement a value of Qdec = 0.03 was obtained. As can be seen from the wavelength dependence of the photocycloreversion quantum yield Q1, cycloreversion occurs not only from the thermalized S2(πccπ*cc) but from higher excited states too. The maximum quantum yield was found at 302 nm to be (Q1 = 0.15. From our results it follows that this endoperoxide is of high quality in respect to the colour change colourless/blue and to thermal stability, whereas the reversibility is only moderate.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/74322
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-743223
SN  - 1865-7109
VL  - 39
IS  - 10
SP  - 998
EP  - 1002
PB  - Verlag der Zeitschrift für Naturforschung
CY  - Tübingen
ER  -