Pentacene oxidation, product

In particular, it was shown that 6,13-pentacenequinone (the product of pentacene oxidation) forms electronic defects in pentacene, and careful purification of the commercially available material by vacuum sublimation is required to achieve a significant reduction of this impurity [85]. Following an extensive purification procedure, it has been estimated from SCLC measurements that the bulk density of traps in ultrapure pentacene crystals can be as low as 2 10" cm. However, the density of traps can be considerably larger close to the crystal surface, which is normally exposed to the environment during the OFET assembly. 

Recently the preparation of 2,3,9,10-tetrakis(trimethylsilyl)pentacene 14 was reported [28]. Although this compound is significantly more soluble than 12 and 13, it was reported to be quite unstable, surviving only a week in deoxygenated solution and for a few days in the crystalline state. The oxidation potential of this compound is 725 mV (vs. SCE), significantly higher than that reported for pentacene. The structure of this compound was confirmed by crystallographic analysis of one of the decomposition products - the butterfly dimer 15 (Fig. 3.4). 

Bernstein et al. have used IR spectroscopy and mass spectrometry to study the products formed from photochemical transformation of naphthalene, anthracene, chrysene, phenanthrene, pyrene, tetracene, pentacene, perylene, benzo(e)pyrene, benzo(ghi)perylene, and coronene in water ices using ultraviolet radiation under astrophysical conditions [27]. The results of their investigation have revealed that peripheral carbon atoms can be oxidized to produce aromatic alcohols, ketones, ethers (when bay region is present,... 

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