Xanthene‐Separated 24 π‐Electron Antiaromatic Rosarin Dimer

Abstract

AbstractAntiaromatic molecules have recently received attention because of their intrinsic properties, such as high reactivity and their narrow HOMO–LUMO gaps. Stacking of antiaromatic molecules has been predicted to induce three‐dimensional aromaticity via frontier orbital interactions. Here, we report a covalently linked π‐π stacked rosarin dimer that has been examined experimentally by steady‐state absorption and transient absorption measurements and theoretically by quantum chemical calculations, including time‐dependent density functional theory, anisotropy of induced current density, and nucleus‐independent chemical shift calculations. Relative to the corresponding monomer, the dimer exhibits diminished antiaromaticity upon lowering the temperature to 77 K, a finding ascribed to intramolecular interactions between the macrocyclic rosarin subunits.