Ordered co-assembly based on chiral phenylalanine derivatives and achiral coumarin derivatives

The self-assembly of small molecules into supramolecular hydrogels is of great significance in mimicking biological systems. In this study, we investigated the formation and structure change of supramolecular hydrogels based on the self-assembly behavior of an achiral coumarin derivative (G1) and a chiral phenylalanine derivative (ALP). It was observed that G1 and ALP can self-assemble at various molar ratios, resulting in distinct nanostructured morphologies. Specifically, at a molar ratio of G1/ALP (4 : 1), the achiral G1 molecules initially bifurcate and diverge, ultimately forming a dendritic microstructure at the G1 termini. When the G1/ALP ratio was adjusted to 2 : 1, a chrysanthemum-like microstructure emerged. UV-light can destroy the self-assembled gel structure of different G1/ALP ratios, changing it from gel to sol. The emergence of these higher-order chiral structures during self-assembly was attributed to hydrogen bonding and π-π stacking interactions between the molecules. This research offers valuable insights into the understanding of biological self-assembly processes and the design of artificial biomedical materials.