On-Surface Site-Selective Cyclization of Corrole Radicals

ACS Nano. 2017 Mar 28;11(3):3383-3391. doi: 10.1021/acsnano.7b00766. Epub 2017 Mar 1.

Abstract

Radical cyclization is among the most powerful and versatile reactions for constructing mono- and polycyclic systems, but has, to date, remained unexplored in the context of on-surface synthesis. We report the controlled on-surface synthesis of stable corrole radicals on Ag(111) via site-specific dehydrogenation of a pyrrole N-H bond in the 5,10,15-tris(pentafluoro-phenyl)-corrole triggered by annealing at 330 K under ultrahigh-vacuum conditions. We reveal a thermally induced regioselective cyclization reaction mediated by a radical cascade and resolve the reaction mechanism of the pertaining cyclodefluorination reaction at the single-molecule level. Via intramolecularly resolved probing of the radical-related Kondo signature, we achieve real space visualization of the distribution of the unpaired electron density over specific sites within the corrole radical. Annealing to 550 K initiates intermolecular coupling reactions, producing an extended π-conjugated corrole system.

Keywords: corrole; cyclization; defluorination; network; radical cascade reactions; regioselectivity; surface.

Publication types

  • Research Support, Non-U.S. Gov't