A Comprehensive Enhancement of the Photochemical Properties of Metal Nanoclusters via Ligand‐Tailoring and Fluorine‐Incorporation

ABSTRACT Metal nanoclusters have garnered significant research interest over the past two decades due to their unique photochemical properties. Herein, we synthesize Au 25 nanoclusters with various previously unused surface ligands. By systematically comparing their photoinitiation, photoluminescence, and photothermal effects, combined with comprehensive analysis of prior research findings, we elucidated a comprehensive, systematic structure‐activity relationship between ligand structure and nanocluster photochemistry. Notably, a new Au 25 (S‐Ph‐CF 3 ) 18 − (HS‐Ph‐CF 3 : 4‐trifluoromethyl‐benzenethiol) demonstrates exceptional performance across all the three photochemical processes, particularly in photoluminescence. It exhibits remarkable near‐infrared (NIR‐II) solid‐state fluorescence quantum yield of 10–13% at 1100 nm wavelength under room temperature, representing a competitive value among related materials to date at this wavelength range, and it also displays a high photothermal conversion efficiency of 56.2%. In terms of photoinitiation, Au 25 (S‐Ph‐CF 3 ) 18 − not only maintains the original printing sensitivity during two‐photon initiation, it also produces finer structures with enhanced formability. Single‐crystal X‐ray diffraction analysis reveals six distinct π···π stacking interactions between the thiophenol ligands in Au 25 (S‐Ph‐CF 3 ) 18 − , which effectively suppress intramolecular vibrational and rotational motions, leading to the enhanced quantum yield. This study systematically investigates ligand‐engineered Au 25 nanoclusters, providing in‐depth insights into their different photochemical characteristics. Furthermore, it develops a fluorine‐containing gold nanocluster with superior integrated optical properties.