Triarylborane‐Functionalized Au₈Ag₈(CCR)₁₆ Nanocluster with Enhanced Lewis Acidity

Abstract Functionalization of ligated metal nanoclusters with versatile ligands is highly desired for wide applications. Lewis acids have shown promise in multiple realms such as self‐assembly and catalysis, which may endow nanoclusters with diverse functions. However, metal nanoclusters with Lewis acid surface have not been reported. Here, the functionalization of a bimetallic nanocluster Au₈Ag₈(CCR)₁₆ with triarylborane (TAB) is reported, which exhibits enhanced Lewis acidity. By using single‐crystal X‐ray crystallography, the structure of the nanocluster with 16 boron receptor sites is confirmed, which presents ≈15‐fold enhancement of quenching efficiency in sensing fluoride compared to that of free triarylborane ligand. By the combined analysis using ultrafast transient absorption and photoluminescent (PL) decay measurements, the quenching mechanism of Au₈Ag₈ to fluoride is elucidated. The PL quenching is realized via two pathways with enhanced non‐radiation energy dissipation, i.e., prolonged electron–phonon coupling and reverse intersystem crossing (RISC). This work may open a new route to diverse applications of metal nanoclusters.