Isostructural Nanocluster Manipulation Reveals Pivotal Role of One Surface Atom in Click Chemistry

Elucidating single-atom effects on the fundamental properties of nanoparticles is challenging because single-atom modifications are typically accompanied by appreciable changes to the overall particle's structure. Herein, we report the synthesis of a [Cu58H20PET36(PPh3)(4)](2+) (Cu-58; PET: phenylethanethiolate; PPh3: triphenylphosphine) nanocluster-an atomically precise nanoparticle-that can be transformed into the surface-defective analog [Cu57H20PET36(PPh3)(4)](+) (Cu-57). Both nanoclusters are virtually identical, with five concentric metal shells, save for one missing surface copper atom in Cu-57. Remarkably, the loss of this single surface atom drastically alters the reactivity of the nanocluster. In contrast to Cu-58, Cu-57 shows promising activity for click chemistry, particularly photoinduced [3+2] azide-alkyne cycloaddition (AAC), which is attributed to the active catalytic site in Cu-57 after the removal of one surface copper atom. Our study not only presents a unique system for uncovering the effect of a single-surface atom modification on nanoparticle properties but also showcases single-atom surface modification as a powerful means for designing nanoparticle catalysts.