Aromaticity and superaromaticity in cyclopolyacenes
The topological resonance energy (TRE) method has been applied to linear and zigzag isomers of cyclopolyacenes to investigate their aromatic character. In general, zigzag cyclopolyacenes are found to be highly aromatic. Every linear cyclopolyacene is much less aromatic than the zigzag isomer, and large linear and zigzag cyclopolyacenes are as aromatic as their respective polyacenes. A Hückel-like rule is observed for linear cyclopolyacenes. A super-ring structure scarcely affects the aromatic character of sizeable cyclopolyacenes.