Ligand‐Driven Structural Modulation and Enhanced Photoluminescence in High‐Nuclearity Ag 56 Nanoclusters

ABSTRACT Atomically precise silver nanoclusters (AgNCs) offer unique opportunities to correlate structure and photophysical properties, yet enhancing their photoluminescence emission remains challenging due to dominance of non‐radiative decay pathways. Here, we report a ligand‐engineering strategy to modulate the optical properties of high‐nuclearity Ag 56 NCs. The synthesized two NCs, Ag 56 S 12 ( t BuS) 20 (CF 3 CO 2 ) 12 (MeCN) 3 (NC‐I) and Ag 56 S 12 ( t BuS) 20 ( n BuSO 3 ) 12 (NC‐II), possess a similar hexagonal‐close‐packed Ag 14 kernel, which is encapsulated by a similar icosahedral S 12 middle‐shell and an outer Ag 42 shell, but differ in overall symmetry and outer Ag‐ligand shell connectivity. Replacement of bidentate CF 3 CO 2 − with tridentate n BuSO 3 − ligands increases overall Ag─ X ( X = O, S, and Ag) bonding interactions, resulting in not only a more rigid and compact outer Ag 42 shell structure but also contraction of cationic Ag 14 core and anionic icosahedral S 12 middle‐shell. These structural modifications enhance radiative decay and suppress non‐radiative pathways, leading to a 17‐fold increase in photoluminescence quantum yield and extended average emission lifetime. Computational analysis confirms that ligand‐induced geometric stabilization and electronic delocalization govern the excited‐state dynamics. This work demonstrates that rational ligand design can synergistically tune cluster geometry, rigidity, and electronic structure, providing a general strategy to improve the photophysical performance of high‐nuclearity AgNCs.