Local and global aromaticity in a molecular carbon nanobelt: insights from magnetic response properties in neutral and charged species

The formation of carbon nanobelt made exclusively from fused benzene rings has recently been achieved. Our results reveal an interesting shift from a local aromatic character constrained in each of the six aromatic Clar sextets (6π-electron circuit) to a global aromatic character in charged species (+2 and −2) involving the overall π-circuit from the molecular nanobelt. This demonstrates the suppression of the local aromatic character in favor of a global aromaticity by selecting the oxidation state of the carbon nanobelt, giving rise to a shielding cone extended within the structure.