Single‐Site Metal‐Nonmetal Microenvironment Regulation of Copper Nanoclusters with Atomic Precision for X‐Ray Imaging

Abstract The intramolecular microenvironment regulation in metal nanoclusters has typically occurred with the same attribute factors—like metal‐to‐metal or ligand‐to‐ligand control—while the regulation with different‐attribute factors, e.g., from metal to nonmetal, remains challenging, not to mention the different‐attribute microenvironment regulation at the single‐site level. Herein, we report the single‐site metal‐nonmetal microenvironment regulation of copper nanoclusters based on structurally comparable Cu 10 and Cu 11 nanoclusters with the same skeleton but different vacancy‐filling elements. The quantum‐size effects endow Cu 10 and Cu 11 with distinctly different photophysical properties in terms of their photoluminescence and radioluminescence. Such differences have been rationalized by exploiting the femtosecond transient absorption analysis, demonstrating that the slower non‐radiative decay rate and weaker electron‐phonon coupling contribute to the superior emission characteristics of the Cu 11 cluster. Accordingly, the Cu 11 ‐based film demonstrated effective X‐ray imaging capabilities, marking the first application of cluster‐based nanomaterials for X‐ray imaging in the infrared region. This research highlights the potential for regulating different‐attribute microenvironments in metal nanoclusters and provides an atomic‐level understanding of how to modulate the photophysical properties of cluster‐based nanomaterials.