Benzenoid polycyclic hydrocarbons with an open-shell biradical ground state

This Focus Review describes the recent progress, from both theoretical and experimental perspectives, on four types of benzenoid polycyclic hydrocarbons with an open-shell biradical ground state: 1) acenes, 2) periacenes and anthenes, 3) zethrenes, and 4) extended p-quinodimethane derivatives. These interesting molecules have provided excellent platforms to investigate the electronic structures of nanographenes and represent promising candidates for the next generation of molecule-based materials in the field of electronics, spintronics, and non-linear optics. The focus of this article will be put on the structural significance, the physical properties relevant to the open-shell electronic configurations, and potential applications.