A Study on the Aromaticity of [n]Circulene (n = 3–8)

The topological resonance energy method was employed to analyze [n]circulene systems (n = 3–8) and predict their aromaticity. Calculations revealed that all compounds exhibit some aromatic properties. Local aromaticity of each ring was assessed using bond resonance energy (BRE), circuit resonance energy, and magnetically based superaromatic stabilization energy (m-SSE) indices. Our results indicate that the BRE method overestimates the degree of local aromaticity in the central ring. The local aromaticity, as determined by the m-SSE index, has been compared with other ring indices reported in the literature. Additionally, the Hückel–London ring current model was used to study aromaticity, showing that molecular perimeters sustain diamagnetic bond currents, whereas central rings sustain paramagnetic bond currents. For the individual rings, both the energetic and magnetic criteria of aromaticity predict similar trends in the magnitude of local aromatic and antiaromatic states.