The geometry-dependent self-assembling features of two PAHs, 1 and 2, are reported. The more planar 1 forms H-type supramolecular polymers, in a highly cooperative fashion, by a combination of H-bonding and π-stacking, with rod-like morphology. However, the highly distorted 2 interacts only by means of H-bonding with no contact between the aromatic units, yielding lamellar supramolecular structures.