Open-shell polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) with unpaired or partially unpaired electrons will display open-shell radical character (monoradical, biradical, polyradical). This will lead to special features in electronic structures, magnetic properties and crystalline packing, which endow them with great potential as a new generation of materials. Stability issues are always the focus on the way towards functionalized open-shell PAHs, and chemists have made huge endeavours in synthesizing stable PAHs with open-shell characters. In this article, we summarize recent developments on open-shell PAHs covering both theoretical advances and experimental progresses, and touch on a few examples of them for practical applications.