Synthesis, Properties, and Packing Structures of Corannulene-Based π-Systems Containing Heptagons.
Introduction of heptagons into hexagonal carbon lattices can generate negatively curved polycyclic aromatic hydrocarbons, which are of significant interest in the field of exotic molecular nanocarbons. We have successfully synthesized and characterized corannulene-based π-systems containing heptagons (4 and 5) as new negatively curved polycyclic aromatic hydrocarbons as well as possible intermediates in the synthesis of warped nanographene 1. The formation of 4 and 5 represents the first example for which a heptagon is formed under Scholl reaction conditions before all hexagons are formed. Even more interestingly, we discovered that the mode and degree of solid-phase intermolecular π-π interaction can be altered significantly by the degree of ring closure.