Stereochemical preorganization directs triple-helical assembly of Au₄ nanoclusters

Programming hierarchical helicity from molecular stereochemistry remains a major challenge in synthetic materials. Collagen achieves this through conformational preorganization that translates local stereochemical information into homochiral triple helices, a level of hierarchical control rarely realized in artificial systems. Here we show that atomically precise Au₄ nanoclusters encode local stereochemical information into a homochiral triple helix through a collagen-inspired assembly mechanism. A configuration-dependent endo-exo puckering of thiazolidine-2-thione ligands acts as a stereochemical switch, controlling metal-site exposure and biasing Au···Au metallophilic interactions. This intrachain preorganization fixes the torsional geometry of single helices, which then cooperatively braid into left-handed and right-handed triple helices, respectively. Systematic steric modulation redirects the assembly into alternative architectures, demonstrating programmable control over helicity. The triple-helical superstructures exhibit amplified chiroptical responses. These results establish a transferable molecular grammar for hierarchical helicity in metal nanoclusters and identify metallophilicity as a design principle for biomimetic materials.