Intramolecular Aggregation-Induced Surface Coupling of Metal Nanoclusters: Structure Elucidation and Photoluminescence Manipulation

The restriction of the molecular motion has been extensively exploited in tailoring the photoluminescence (PL) of metal nanoclusters, while the activation of such a restriction at the molecular level remains highly challenging. In this work, a two-step strategy, that is, surface activating and surface coupling, was proposed to induce the restriction of the molecular motion of nanoclusters at the molecular level, and the corresponding nanoclusters underwent emission appearance and enhancement. The peripheral phosphine ligand functionalization and alkali metal cation introduction gave rise to a series of structural-correlated M⁺-incorporated Cu₁₄ nanoclusters (M = Li, Na, K, Rb, Cs) with a surface-aggregation characteristic, among which the K⁺-participating nanocluster displayed the strongest fluorescence intensity in both solution and crystal states. Atomic-level structure–property correlations were investigated to rationalize the PL comparisons. Overall, this work offers a new perspective for regulating the PL of metal nanoclusters via restricting their molecular motions, hopefully providing insight into the fabrication of highly emissive metal nanoclusters and cluster-based nanomaterials.