Lanthanide(III)‐Cu4I4 Organic Framework Scintillators Sensitized by Cluster‐Based Antenna for High‐Resolution X‐ray Imaging

Scintillator‐based X‐ray imaging has attracted great attention from industrial quality inspection and security to medical diagnostics. Herein, a series of lanthanide(III)‐Cu4I4 heterometallic organic frameworks (Ln‐Cu4I4 MOFs)‐based X‐ray scintillators are developed by rationally assembling X‐ray absorption centers ([Cu4I4] clusters) and luminescent chromophores (Ln(III) ions) in a specific manner. Under X‐ray irradiation, the heavy inorganic units ([Cu4I4] clusters) absorb the X‐ray energy to populate triplet excitons via halide‐to‐ligand charge transfer (XLCT) combined with the metal‐to‐ligand charge‐transfer (MLCT) state (defined as the X/MLCT state), and then the 3X/MLCT excited state sensitizes Tb3+ for intense X‐ray‐excited luminescence via excitation energy transfer. The obtained Tb‐Cu4I4 MOF scintillators exhibit high resistance to humidity and radiation, excellent linear response to X‐ray dose rate, and high X‐ray relative light yield of 29 379 ± 3000 photons MeV−1. The relative light yield of Tb‐Cu4I4 MOFs is ≈3 times higher than that of the control Tb(III) complex. X‐ray imaging tests show that the Tb‐Cu4I4 MOFs‐based flexible scintillator film exhibits a high spatial resolution of 12.6 lp mm−1. These findings not only provide a promising design strategy to develop lanthanide‐MOF‐based scintillators with excellent scintillation performance, but also exhibit high‐resolution X‐ray imaging for biological specimens and electronic chips. A series of lanthanide(III)‐Cu4I4 heterometallic organic frameworks (Ln‐Cu4I4 MOFs)‐based X‐ray scintillators is developed by rationally assembling X‐ray absorption centers ([Cu4I4] clusters) and luminescent chromophores (Ln(III) ions) in a specific manner. High‐efficient excitation energy transfer from the cluster‐based antenna to the Ln(III) ions enables Ln‐Cu4I4 MOFs and their flexible film with excellent scintillation performance and high spatial resolution of 12.6 lp mm−1.