Acenes, higher, oxidation

Copolymers 113 and 114 containing tetracene and pentacene units show emission from the acene units to give green (A.max = 520 nm) and red (A-max = 623 nm) PL and EL, respectively [220]. However, due to rapid degradation of the acenes by oxidation their emission rapidly turns blue and the emission efficiency drops markedly. The pentacene copolymer 114 shows a lower turn-on voltage and higher efficiency with 1 mol % as opposed to 10 mol % of pentacene. 

Oxidation of anthracene or higher acenes also occurs in the absence of a dye, since the same substrates act as sensitizers in singlet oxygenation [9c,42a]. These compounds react mainly at the mexo-positions of the aromatic nucleus [49a], but electron-donating groups have a strong directing effect when placed at the 1- and 4-positions (Sch. 33) [49b]. 

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