The Emergence of Chirality in Time and Space: Transient Asymmetry in Supramolecular Polymers Triggered by Visible Light

Asymmetry is a fundamental property in the molecular organization of life, but how it emerges and propagates remains elusive. One-dimensional assemblies formed through reversible, non-covalent interactions can adopt helical conformations and reorganize slowly, making them powerful model systems for studying the emergence and persistence of asymmetry in aqueous environments. Recent studies have shown that chiral surfactants can transfer their stereogenic information, inducing a helical bias in supramolecular polymers. Here, using light as a non-invasive trigger, we demonstrate how two phenomena with different kinetics amplify the asymmetry in coassemblies of racemic supramolecular polymers and chiral surfactants. Upon irradiation, the photoresponsive merocyanine surfactant undergoes quick isomerization into its more hydrophobic spiropyran form, enhancing its interaction with the racemic supramolecular polymer and inducing a helical bias that develops and persists on time scales that far exceed the lifetime of the molecular trigger. This light-driven asymmetry is fully reversible and involves metastable structures, which can be further promoted by brief, well-timed light pulses. These limited light pulses can induce and sustain asymmetric states in water-compatible supramolecular polymers, opening avenues for dynamic supramolecular materials with non-equilibrium features toward life-like adaptive systems.