Organic chemistry of π-conjugated polycyclic aromatic hydrocarbons: Acenes and phenacenes

Polycyclic aromatic hydrocarbons (PAHs) are of great importance from the aspect of fundamental sciences as well as materials science, especially in organic electronics. In this chapter, the electronic features, synthesis strategies, and representative reactions of two series of π-conjugated PAHs, acenes and phenacenes, are described. In the last two decades, pentacene has been widely investigated as an organic electronic material, e.g., as the active layer of organic field-effect transistors (OFETs). Picene, which is an isomer of pentacene with a phenacene structure, was also found to serve as an active layer in high-performance OFETs. While pentacene is unstable under exposure to light and oxygen, picene is quite stable under such conditions. The electronic and chemical features of acene and phenacene are thus compared to understand the differences in the nature of the two structural categories of PAHs.