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

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 Cu₁₀ and Cu₁₁ nanoclusters with the same skeleton but different vacancy-filling elements. The quantum-size effects endow Cu₁₀ and Cu₁₁ 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 Cu₁₁ cluster. Accordingly, the Cu₁₁-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.