Surpassing homochiral assemblies in chiroptical activity through enantiomeric imbalance

Amplifying asymmetry via supramolecular self-assembly is essential for understanding homochirality in biology and developing functional chiroptical materials. While the “majority rules” dictates the handedness of heterochiral assemblies, their chiroptical signals are typically weaker than those of homochiral ones. Here, we demonstrate that controlled enantiomeric imbalance can enhance chiroptical activity beyond that of homochiral assemblies. Using dansyl-glutamic acid diamide enantiomers, we show that fine-tuning enantiomeric excess (ee) triggers structural reorganization, yielding maximum circular dichroism (CD) and circularly polarized luminescence (CPL) intensities exceeding those of pure enantiomer assemblies at specific ee values. Simulations reveal that the incorporation of the minority enantiomer constructively forms “chiral oligomers”, which are composed of different ratios of enantiomers and optimize local chromophore alignment via effective pitch angle to amplify the chiroptical activity. This strategy overcomes the conventional signal attenuation from racemic or near-racemic mixing, enabling chiral imbalance–driven asymmetric amplification and offering a rational design principle for high-performance chiroptical materials. While the “majority rules” dictates the handedness of heterochiral assemblies, their chiroptical signals are typically weaker than those of homochiral ones. Here, the authors demonstrate that controlled enantiomeric imbalance can enhance chiroptical activity beyond that of homochiral assemblies.