'Broken-hearted' carbon bowl via electron shuttle reaction: energetics and electron coupling†

Unprecedented one-step C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 C bond cleavage leading to opening of the buckybowl (π-bowl), that could provide access to carbon-rich structures with previously inaccessible topologies, is reported; highlighting the possibility to implement drastically different synthetic routes to π-bowls in contrast to conventional ones applied for polycyclic aromatic hydrocarbons. Through theoretical modeling, we evaluated the mechanistic pathways feasible for π-bowl planarization and factors that could affect such a transformation including strain and released energies. Through employment of Marcus theory, optical spectroscopy, and crystallographic analysis, we estimated the possibility of charge transfer and electron coupling between “open” corannulene and a strong electron acceptor such as 7,7,8,8-tetracyanoquinodimethane. Alternative to a one-pot solid-state corannulene “unzipping” route, we reported a nine-step solution-based approach for preparation of novel planar “open” corannulene-based derivatives in which electronic structures and photophysical profiles were estimated through the energies and isosurfaces of the frontier natural transition orbitals.
An electron shuttle contributed to breaking corannulene's heart through a unique one-step reductive CC bond cleavage in the traditionally robust π-bowl. The heartbreak did not stop there as “broken analogs” were developed through a solution-phase route.