Atomically Precise Site-Specific Tailoring and Directional Assembly of Superatomic Silver Nanoclusters

Convenient generation of stable superatomic silver clusters and their systematic site-specific tailoring and directional assembly present an enduring and significant challenge. In this work, we prepared a face-centered cubic (fcc) array of Ag₁₄ superatoms protected by face-capping 1,2-dithiolate-o-carborane (C₂B₁₀H₁₀S₂) ligands, each produced from 1-thiol-o-carborane in crystallization with simultaneous reduction of Ag⁺ to Ag⁰. We find that the corner N-donor ligands contribute predominately to the stability and luminescence of the Ag₁₄ superatom. As the first-formed nanocluster [Ag₁₄(C₂B₁₀H₁₀S₂)₆(CH₃CN)₈]·4CH₃CN (NC-1) with labile vertex-coordinated CH₃CN ligands is highly unstable, monodendate pyridine ligands were used to replace these CH₃CN species site-specifically, giving [Ag₁₄(C₂B₁₀H₁₀S₂)₆(pyridine/p-methylpyridine)₈] (NCs-2,3) in gram scale with its core structure intact, which features ultrastability up to 150 °C in air. Moreover, using bidentate N-containing ligands to bridge the superatomic Ag₁₄ building blocks, we constructed an unprecedented hierarchical series of 1D-to-3D superatomic silver cluster-assembled materials (SCAM-1,2,3,4), and SCAM-4 is air-stable up to 220 °C. Furthermore, this series of stable solid-state superatomic-nanocluster materials exhibit tunable dual emission with wide-range thermochromism. The present study constitutes a major step toward the development of ligand-modulation of the structure, stability, assembly, and functionality of superatomic silver nanoclusters.