Superoxide Radical Mediated Branch and Crosslink Growth of FCC Kernel in Gold Nanoclusters.

FCC (face-centered cubic) structures are found to be highly prevalent in both bulk Au and Au nanoclusters, but achieving precise tailoring or the formation of new stacking modes based on FCC structure has proved challenging. Here, we show a radical-induced structure transformation strategy using persulfates that results in the formation of three new nanoclusters: Au41(SR)25, Au46(SR)26, and Au49(SR)27 (SR: thiolate). The double helices of Au4 assemblies in their kernel structures are observed to adopt branch and cross-linked growth beyond that of linear growth in the previous FCC-kernelled structure. The superoxide radicals converted from persulfates are revealed to oxidize the Au44 precursors with a concurrent Au‒S cleavage, leading to the formation of thermodynamically stable nanoclusters, which are confirmed by theoretical calculations and experimental results. This study unveils new perspectives on the reactivity of atomically precise NCs and highlights a radical-based strategy to design more kernel packing structures.