Chiral Dominance in Supramolecular Co-assemblies via Cation-π Driven Stereochemical Locking.

Controlling supramolecular chirality in multicomponent systems remains a significant challenge due to competing stereochemical interactions. In this study, we report a case of competitive chiral dominance in binary co-assemblies composed of enantiomeric tartaric acid derivatives (a1 and a2) and enantiomeric pyridine derivatives (R/S-py). The dibenzoyl-substituted tartaric acid (a1) is capable of overriding the chirality of the co-assemblies by protonating the chiral pyridines to form pyridinium-carboxylate pairs. This interaction induces in situ cation-π interactions, leading to the formation of stereoconfiguration-locked H-aggregates. In contrast, the pivaloyl-substituted tartaric acid (a2) exhibits chirality bias governed by the enantiopure pyridine derivatives, attributed to its increased steric bulk and the absence of cation-π interactions. These findings not only advance the fundamental understanding of stereochemical communication but also offer a new strategy for controlling hierarchical chirality in complex supramolecular systems.