Synthesis and Characterization of Quarteranthene: Elucidating the Characteristics of the Edge State of Graphene Nanoribbons at the Molecular Level

The characteristics of the edge state, which is a peculiar
magnetic
state in zigzag-edged graphene nanoribbons (ZGNRs) that originates
from electron–electron correlation in an edge-localized π-state,
are investigated by preparing and characterizing quarteranthene molecules.
The molecular geometry that was determined from the X-ray analysis
is consistent with a zigzag-edge-localized structure of unpaired electrons.
The localized electrons are responsible for the peculiar magnetic
(room-temperature ferromagnetic correlation), optical (the lowest-lying
doubly excited state), and chemical (peroxide bond formation) behaviors.
On the basis of these distinguishing properties and a careful consideration
of the valence bonding, insight into the edge state of ZGNRs can be
gained.