6533b7d0fe1ef96bd125a3f0

RESEARCH PRODUCT

Breaking Bonds and Forming Nanographene Diradicals with Pressure.

subject

description

New anthanthrone-based polycyclic scaffolds possessing peripheral crowed quinodimethanes have been prepared. While the compounds adopt a closed-shell butterfly shaped structure in the ground state, a concave-to-convex fluxional dynamic inversion is accessible with a low energy barrier through an open-shell diradicaloid transition-state. Mainly driven by the release of strainattributed to the steric hindrance at the peri position of the anthanthrone core, a low-lying open-shell diradical is accessible through planarization of the core, which can be achieved by thermal excitation in solution. Alternatively, planarization can be achieved by application of mild pressure in the solid state, in which case the diradical remains kinetically trapped in an excited open-shellconfiguration. Cross-information from quantum chemistry, Ramanspectroscopy and magnetic experiments allow us to corroborate thesehypotheses and determine that the resulting nanographene-likestructure possess unpaired electrons mainly localized at the exoanthanthrenecarbons bearing phenyl substituents.