Au₂₅ Cluster-Based Atomically Precise Coordination Frameworks and Emission Engineering through Lattice Symmetry

The atomically precise metal nanoclusters (NCs) have attracted significant attention due to their superatomic behavior originating from the quantum confinement effect. This behavior makes these materials suitable for various photoluminescence-based applications, including chemical sensing, bioimaging, and phototherapy, owing to their intriguing optical properties. Especially, the manipulation of inter- or intracluster interaction through cluster-assembled materials (CAMs) presents significant pathways for modifying the photophysical properties of NCs. Herein, two distinct CAMs, Au-Zn-Hex and Au-Zn-Rod, were synthesized via forming a coordination bond between [Au₂₅(p-HMBA)₁₈]^- (p-H₂MBA = 4-mercaptobenzoic acid) and Zn²⁺. Au-Zn-Rod exhibited a 6-fold higher luminescence intensity in the near-infrared region compared to Au-Zn-Hex, attributed to synergistic inter- and intracluster interactions that induce exciton delocalization and structure rigidification at the atomic scale. This study highlights the potential of diverse lattice symmetries in cluster-based frameworks for tuning the photophysical properties, contributing to a deeper understanding of the structure-property relationship in Au NCs.