Conjugated benzenoid aromatics with large inner cavities and alkyl side chains self‐associate to produce dimers in solution and fibrous materials in the solid state. The self‐association is enthalpically and entropically driven. The compound forms a 1:3 charge‐transfer (CT) complex with 2,4,7‐trinitrofluorenone (TNF) with a microball structure, where a nano‐sized branched structure forms first at the