Solvatochromism of Amphiphilic Au₂₅(SR)₁₈ Nanoclusters Based on Supramolecular Ligand–Thiolated Crown Ether

Atomically precise nanoclusters find multiple applications in, for example, bioimaging or as catalysts due to their remarkable molecule-like properties which are tightly bound to their strictly defined structures. However, their physicochemical characterization and broad utilization in the aforementioned areas are often challenging due to the limited solubility. Herein, we report the synthesis of Au₂₅ nanoclusters (NCs) capped with 2-mercaptomethyl-12-crown-4 ether, imparting amphiphilic properties that confer solubility in both polar and nonpolar solvents. UV-vis spectroscopy confirmed the stability of the Au₂₅ framework in polar protic and apolar aprotic solvents. Moreover, FTIR analysis suggests that our supramolecular ligand responds to solvent polarity and protic/aprotic conditions, adjusting its conformation on the cluster surface. Furthermore, accompanying variations in photoluminescence underscore their potential utility as environmentally responsive polarity-sensitive probes. These findings establish a versatile Au₂₅ nanocluster platform for investigating structure-property relationships in diverse chemical environments without requiring additional chemical modifications to the cluster structure.