Constructing Lanthanide‐Organic Complexes for X‐ray Scintillation and Imaging

Abstract The photoluminescent properties of lanthanide complexes have been thoroughly investigated; however, there have been much fewer studies showcasing their potential use in ionizing radiation detection. In this work, we delve into the photo‐ and radio‐induced luminescence of a series of lanthanide‐bearing organic‐inorganic hybrids and their potential as a platform for X‐ray scintillation and imaging. The judicious synergy between lanthanide cations and 2,6‐di(1H‐pyrazol‐1‐yl)isonicotinate (bppCOO−) ligands affords six new materials with three distinct structures. Notably, Eu‐bppCOO‐1 and Tb‐bppCOO‐2 display sharp fingerprint X‐ray‐excited luminescence (XEL), the intensities of which can be linearly correlated with the X‐ray dose rates over a broad dynamic range (0.007–4.55 mGy s−1). Moreover, the X‐ray sensing efficacies of Eu‐bppCOO‐1 and Tb‐bppCOO‐2 were evaluated, showing that Tb‐bppCOO‐2 features a lower detection limit of 4.06 μGy s−1 compared to 14.55 μGy s−1 of Eu‐bppCOO‐1. Given the higher X‐ray sensitivity and excellent radiation stability of Tb‐bppCOO‐2, we fabricated a flexible scintillator film for X‐ray imaging by embedding finely ground Tb‐bppCOO‐2 in the polydimethylsiloxane (PDMS) polymer. The resulting scintillator film can be utilized for high‐resolution X‐ray imaging with a spatial resolution of approximately 7 lp mm−1.