Engineering the racemization barrier in Z-shaped perylenediimides: axial chirality governs the self-assembly of core-twisted scaffolds.

In this work, we describe the demanding synthesis of two core-twisted Z-shaped perylenediimide derivatives, 1 and 2, together with the separation of their individual M and P enantiomers. Z-PDI 1 exhibits axial chirality as its only source of asymmetry, whereas Z-PDI 2 incorporates also peripheral stereogenic centers. Their self-assembly behavior was examined in detail, and multiple spectroscopic methods collectively indicate that these systems generate luminescent, chiral supramolecular polymers. The assembly process is governed by intermolecular hydrogen bonding among the peripheral trialkoxybenzamide units and occurs without significant π-stacking between the aromatic cores. By combining spectroscopic data with structural characterization and theoretical modeling, we find that axial chirality plays the dominant role in controlling supramolecular organization, surpassing the influence of point chirality. The twist-induced chiral axis dictates both the packing arrangement and the chiroptical response of the assemblies, effectively diminishing the role of the peripheral stereocenters. Overall, these results shed light on the relative importance of different chiral elements in π-conjugated systems and highlight axial chirality as an effective strategy for directing the self-assembly of functional organic materials.