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

ABSTRACT 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 ({Cu 6 S 6 }) and emissive copper‐iodide clusters ({Cu 2 I 2 }). 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.