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 [Cu₅₈ H₂₀ PET₃₆ (PPh₃ )₄ ]²⁺ (Cu₅₈ ; PET: phenylethanethiolate; PPh₃ : triphenylphosphine) nanocluster-an atomically precise nanoparticle-that can be transformed into the surface-defective analog [Cu₅₇ H₂₀ PET₃₆ (PPh₃ )₄ ]⁺ (Cu₅₇ ). Both nanoclusters are virtually identical, with five concentric metal shells, save for one missing surface copper atom in Cu₅₇ . Remarkably, the loss of this single surface atom drastically alters the reactivity of the nanocluster. In contrast to Cu₅₈ , Cu₅₇ shows promising activity for click chemistry, particularly photoinduced [3+2] azide-alkyne cycloaddition (AAC), which is attributed to the active catalytic site in Cu₅₇ 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.