Capturing Ag6 Inner-Core Contraction in Inorganic-Template-Stabilized Ag78 Nanoclusters

Abstract

Abstract Resolving how subangstrom changes in a metal core affect electronic structure and photophysical properties in high-nuclearity silver nanoclusters (NCs) remains challenging, as inner-core variations are often coupled with changes in outer metal shells, surface coordination, or crystal packing. Here, we report a structurally homologous series of Ag78 NCs (Ag78-1–Ag78-4) sharing a common Ag6@Ag24@Ag48 metal architecture stabilized by an S2–/SO42– inorganic template framework. The inorganic template layer stabilizes the metal architecture and reduces structural perturbations from the outer coordination environment, allowing localized Ag6 contraction while largely retaining the overall metal–inorganic architecture. Removal of the central Cl– template in Ag78-1 produces a distinct inward contraction of the Ag6 core in Ag78-2, and surface chloride substitution further accesses more contracted structural states (Ag78-3 and Ag78-4). These structural evolutions are established by single-crystal X-ray diffraction and supported by ESI-MS. Steady-state spectroscopy reveals progressive modulation of low-energy absorption and emission behavior across the series. Theoretical calculations show that central Cl– removal and accompanying Ag6 contraction reorganize low-energy electronic states, and femtosecond transient absorption across the series reveals corresponding changes in excited-state relaxation dynamics. This work establishes an inorganic-template-stabilized Ag78 platform for correlating atomically resolved inner-core structural evolution with electronic structures and excited-state properties in high-nuclearity silver NCs.