Lighting Up Copper Sulfide Nanoclusters via Thioacetamide Introduction

Atomically precise copper sulfide nanoclusters (Cu-S NCs) are of great interest, yet research on their controllable synthesis methods and luminescent properties remains limited. Herein, we report the syntheses and structures of two novel Cu-S NCs: [Cu₂₀S(AT)₈(dppm)₄(H)₈](ClO₄)₂ (Cu₂₀-H) and [Cu₂₀S₃(AT)₁₂(dppm)₂](ClO₄)₂ (Cu₂₀-S), (HAT = 1-adamantanethiol, dppm = bis(diphenylphosphino)methane), with Cu₂₀-S being the first Cu-S NCs prepared via a sulfide-release approach involving thioacetamide. Both clusters exhibit unique structures with regiospecific organic surface coverage: dppm ligands are distributed at both ends of Cu₂₀-H and at one end of Cu₂₀-S. The core of Cu₂₀-H is chiral with D₂ symmetry, whereas the core of Cu₂₀-S exhibits only mirror symmetry. Cu₂₀-H is nearly nonemissive, while Cu₂₀-S exhibits orange luminescence with a high photoluminescence quantum yield (PLQY) of 23.54% and a long lifetime of 10.08 μs at room temperature. The boost in the brightness of Cu₂₀-S can be attributed to its rigid and polar structure, which results from the additional sulfide ions. This work presents a novel approach for constructing Cu-S NCs, enriches the copper cluster family, and provides insights into the luminescent properties of Cu-S NCs.