136809-42-2Relevant articles and documents
Why triple bonds protect acenes from oxidation and decomposition
Fudickar, Werner,Linker, Torsten
, p. 15071 - 15082 (2012/11/06)
An experimental and computational study on the impact of functional groups on the oxidation stability of higher acenes is presented. We synthesized anthracenes, tetracenes, and pentacenes with various substituents at the periphery, identified their photooxygenation products, and measured the kinetics. Furthermore, the products obtained from thermolysis and the kinetics of the thermolysis are investigated. Density functional theory is applied in order to predict reaction energies, frontier molecular orbital interactions, and radical stabilization energies. The combined results allow us to describe the mechanisms of the oxidations and the subsequent thermolysis. We found that the alkynyl group not only enhances the oxidation stability of acenes but also protects the resulting endoperoxides from thermal decomposition. Additionally, such substituents increase the regioselectivity of the photooxygenation of tetracenes and pentacenes. For the first time, we oxidized alkynylpentacenes by using chemically generated singlet oxygen (1O2) without irradiation and identified a 6,13-endoperoxide as the sole regioisomer. The bimolecular rate constant of this oxidation amounts to only 1 × 10 5 s-1 M-1. This unexpectedly slow reaction is a result of a physical deactivation of 1O2. In contrast to unsubstituted or aryl-substituted acenes, photooxygenation of alkynyl-substituted acenes proceeds most likely by a concerted mechanism, while the thermolysis is well explained by the formation of radical intermediates. Our results should be important for the future design of oxidation stable acene-based semiconductors.
Synthesis and Absorption/Emission Spectroscopic Properties of Bis(phenylethynyl)benzenes and 9,10-Bis(phenylethynyl)anthracenes
Nakatsuji, Shin'ichi,Matsuda, Kosei,Uesugi, Yukiko,Nakashima, Kenichiro,Akiyama, Shuzo,Fabian, Walter
, p. 755 - 758 (2007/10/02)
A series of bis(phenylethynyl)benzenes 3 and 9,10-bis(phenylethynyl)anthracenes 4 was synthesized by bromination-dehydrobromination reaction or newly developed direct triple bond formation reaction from styrylstilbenes 1 or distyrylanthracenes 2.Subsequently systematic investigations were carried out on their absorption and fluorescence spectra, and their chemiluminescence properties.The following points are apparent; (a) a linear relationship between and Hammett's ?P of compounds 3 and 4 was observed, (b) a significant relationship between Stokes' shift of 4 and ?P was observed and (c) in the series of compounds 4 the electron-donating ability of the substituents has a pronounced effect on the chemiluminescence properties.