Lanthanide(Ⅲ)-Cu_4I_4 Organic Framework Scintillators Sensitized by Cluster-Based Antenna for High-Resolution X-ray Imaging

摘要

Scintillator-based X-ray imaging has attracted great attention from industrialquality inspection and security to medical diagnostics. Herein, a series oflanthanide(Ⅲ)-Cu_4I_4 heterometallic organic frameworks (Ln-Cu_4I_4 MOFs)-based X-ray scintillators are developed by rationally assembling X-ray absorptioncenters (Cu_4I_4 clusters) and luminescent chromophores (Ln(Ⅲ) ions) ina specific manner. Under X-ray irradiation, the heavy inorganic units (Cu_4I_4clusters) absorb the X-ray energy to populate triplet excitons via halide-toligandcharge transfer (XLCT) combined with the metal-to-ligand chargetransfer(MLCT) state (defined as the X/MLCT state), and then the 3X/MLCTexcited state sensitizes Tb~(3+) for intense X-ray-excited luminescence via excitationenergy transfer. The obtained Tb-Cu_4I_4 MOF scintillators exhibit highresistance to humidity and radiation, excellent linear response to X-ray doserate, and high X-ray relative light yield of 29 379 ± 3000 photons MeV~(?1). Therelative light yield of Tb-Cu_4I_4 MOFs is ≈3 times higher than that of the controlTb(Ⅲ) complex. X-ray imaging tests show that the Tb-Cu_4I_4 MOFs-basedflexible scintillator film exhibits a high spatial resolution of 12.6 lp mm~(?1).These findings not only provide a promising design strategy to developlanthanide-MOF-based scintillators with excellent scintillation performance,but also exhibit high-resolution X-ray imaging for biological specimens andelectronic chips.