Concealed Coronoid Hydrocarbons with Enhanced Antiaromatic Circuit Contributions as Models for Schottky Defects in Graphenes

Abstract

Coronoids with holes shaped like an odd carbon benzenoid have antiaromatic holes and antiaromatic conju- gated circuits. Another class of concealed diradical coronoids has been identified. They are Huckel molecular orbital dira- dicals (HOMO = LUMO = 0, each with a single electron occupancy) that have VB (valence-bond) structures (K � 0).This new class of concealed diradical coronoids have more enhanced antiaromatic contributions. The smallest holes in graphe- nes are spin polarized and have antiaromatic characteristics.