Ultrahigh-Brightness Chiral Lanthanide Organic Framework X-ray Scintillators for Circularly Polarized Luminescence and Advanced Anticounterfeiting

In this study, the multifunctional chiral lanthanide organic frameworks (Ln-MOFs, RR/SS-Eu-MOFs) with circularly polarized luminescence (CPL), second-order nonlinear optics (NLO), and high-performance X-ray scintillator applications were constructed using chiral ligands and Eu(NO₃)₃·6H₂O. The RR/SS-Eu-MOFs exhibited a mirror-symmetric CPL signal at 585 nm for the ⁵D₀ → ⁷F₁ level transition of Eu³⁺, with corresponding asymmetry factors (glum values) of 0.0017 and 0.0066, respectively. The particle size-dependent second harmonic generation (SHG) response was measured using the Kurtz-Perry powder method with a 1064 nm fundamental laser and KDP as a reference. The NLO signal of RR-Eu-MOF increased with increasing particle size, and the maximum SHG response was 0.8 times that of KDP. Moreover, relying on the RR-EuxTb(1-x)MOFs, SS-EuxTb(1-x)MOFs, and RR-Eu-MOF@SS-Tb-MOF hetero structure, they demonstrated the efficient multicolor luminescence behavior of a single crystal, thus constructing a complex multilayered intelligent anticounterfeiting system. Notably, the high-performance RR-Eu-MOF X-ray scintillator boasts a light yield of up to 31,327 photons·MeV⁻¹ and a detection limit as low as 52.8 nGy/s (a 104-fold reduction compared to the typical X-ray medical diagnostic dose (5.5 μGy/s)). This study not only opens new horizons for constructing high-performance chiral Ln-MOF scintillators but also provides a new blueprint for developing multifunctional chiral Ln-MOF emitters.