Highly Water-Stable Uranyl-Cluster Based Metal–Organic Framework for Thermal Adaptive Scintillator

In recent years, uranium-based metal-organic frameworks (MOFs) have garnered particular attention due to the accessible 5f orbitals and diverse coordination geometries of the U atom, as well as the tunability and functionality inherent to MOFs. Herein, we report a 2D-MOF (UO-TTP) featuring a tetranuclear uranyl cluster structure and unique thermal adaptive scintillating characters. UO-TTP exhibits a broad absorption band and can be excited through multiple pathways, from X-ray to one/two-photon excitation. At room temperature, UO-TTP exhibits a continuous emission peak centered at 550 nm, originating from the excited triplet states with hybrid CT characteristics and a long decay lifetime of ∼20 ms. However, at low temperatures, the emission spectra split into finger-type peaks, with lifetimes unexpectedly shortened to microsecond level. This thermal adaptive emission switch was also detected by X-ray excited luminescence (XEL) for the first time. Moreover, UO-TTP shows outstanding stability, with no significant weakening of its luminescence even after soaked in water, and manifests itself as a qualified scintillator in terms of linear response, detection limit, and stability. Based on the excellent optical properties of UO-TTP, we innovatively explored the application of this uranium-organic framework (UOF) in temperature-time dual-correlated information encryption and X-ray imaging under hot water conditions. This work not only reveals the uniqueness and advantages of luminescent UOFs, but also paves the way for in-depth research into actinide chemistry.