Gold clusters assembled homochiral helical microbowties

Construction of artificial microscale helical superstructures holds great significance for understanding hierarchical evolution of chiral architectures in nature. However, fabricating microscale helical superstructures from metal clusters remains mysterious and challenging. Here, we achieved hierarchically assembled helical bowties with micrometer scale via electrostatic interaction-driven co-assembly of chiral Au₄ clusters and trans-1,4-cyclohexanediamine. The size and conformation matching of chiral Au₄ and trans-1,4-cyclohexanediamine compared to the other amines promotes continuous chirality transfer from Au₄ to nanoplatelets and finally to helical microbowties that follows Au₄ molecular chirality. We elucidated hierarchical evolution mechanism of morphology from nanoplatelets to microcake and to helical microbowties through gradual helical stacking and twisting of nanoplatelets. Furthermore, these helical microbowties exhibited excellent switchable photoluminescence and circularly polarized luminescence characteristics governed by dissociation and recombination of electrostatic interactions. This work demonstrates the formation of controllable metal cluster-based helical microbowties and deepens the understanding of chirality transfer and expression at microscale.