π‑Extended Corannulene-Based Nanographenes: Selective Formation of Negative Curvature

A geometrically selective bottom-up
synthesis of curved nanographenes
is described. The synthetic methodology used involves the extension
of the π-system of positively curved corannulene by a [4+2]
cycloaddition reaction followed by cyclodehydrogenation (Scholl oxidation).
By selecting the conditions for the Scholl oxidation, the formation
of a seven-membered ring that also confers negative curvature to the
resulting nanographene can be activated, offering two topologically
distinct, curved nanographenes from a common precursor. Additionally,
the structure–property relationship in these new nanographenes
is explored via theoretical, electrochemical, photophysical, Raman,
and X-ray crystallographic studies.