Unveiling two antiaromatic s-indacenodicarbazole isomers with tunable paratropicity

Abstract

Linear and curved antiaromatic s-indacenodicarbazole isomers were synthesized and characterized to show the tunable paratropicity of s-indacene, as analyzed by NICS(1)_zz and ACID (ring-current) calculations. The curved isomer showed a greater degree of antiaromaticity than the linear isomer, as predicted by the Glidewell–Lloyd rule. This degree of antiaromaticity was further validated by the red-shifted UV-vis absorption and smaller HOMO–LUMO energy gap.