Ultrastable Heterocluster Metal‐Organic Framework Scintillator via Reticular Armoring of Iodocuprate Modules for X‐ray Imaging

Metal-organic framework (MOF)-based scintillators promise advanced X-ray detection and imaging by virtue of their structural tunability. However, the simultaneous attainment of high radioluminescence efficiency, ultralow detection limits, and extreme environmental robustness remains a formidable challenge. Herein, we report a heterocluster MOF scintillator, designated CuSI-MPTZ (MPTZ = 2-mercapto-4-(4-pyridinyl)thiazole), constructed through atomically precise assembly of rigid copper-sulfydryl clusters ({Cu₆S₆}) and emissive copper-iodide clusters ({Cu₂I₂}). This innovative heterocluster design synergistically combines efficient triplet metal-halide-to-ligand charge transfer emission from the Cu-I clusters with intrinsic framework-level protection conferred by hydrophobic tert-butylthiolate shells and rigid Cu-S nodes. The resulting material exhibits unprecedented stability, retaining crystalline integrity after prolonged exposure to 1 M HCl, 10 M NaOH, boiling water for one week, and ambient air for over two years. Under X-ray excitation, CuSI-MPTZ delivers a high light yield exceeding 37600 photons MeV⁻¹, an ultralow detection limit of 81.84 nGy s⁻¹, and a rapid response with minimal afterglow. Large-area flexible composite screens from CuSI-MPTZ achieve a spatial resolution of 11.82 lp mm⁻¹, enabling high-contrast imaging of complex internal structures. This work establishes a transformative paradigm for stable, high-performance, lead-free MOF scintillators, paving the way for practical applications in low-dose medical diagnostics, security screening, and radiation detection in harsh-environments.