Giant Emission Enhancement of Solid-State Gold Nanoclusters by Surface Engineering

Ligand-induced surface restructuring with heteroatomic doping is used to precisely modify the surface of a prototypical [Au₂₅(SR¹)₁₈]⁻ cluster (1) while maintaining its icosahedral Au₁₃ core for the synthesis of a new bimetallic [Au₁₉Cd₃(SR²)₁₈]⁻ cluster (2). Single-crystal X-ray diffraction studies reveal that six bidentate Au₂(SR¹)₃ motifs (L2) attached to the Au₁₃ core of 1 were replaced by three quadridentate Au₂Cd(SR²)₆ motifs (L4) to create a bimetallic cluster 2. Experimental and theoretical results demonstrate a stronger electronic interaction between the surface motifs (Au₂Cd(SR²)₆) and the Au₁₃ core, attributed to a more compact cluster structure and a larger energy gap of 2 compared to that of 1. These factors dramatically enhance the photoluminescence quantum efficiency and lifetime of crystal of the cluster 2. This work provides a new route for the design of a wide range of bimetallic/alloy metal nanoclusters with superior optoelectronic properties and functionality.