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For the first time, we report intense X-ray scintillation enabled by a series of isotypic lanthanide (Eu and Tb) based metal–organic frameworks, initially showing a very efficient X-ray to visible light luminescence conversion. By systematic adjusting of the molar ratio of Eu3+ and Tb3+ in the same MOF structure as a traditional strategy for color-tuning in lanthanide-based photoluminescent materials, linear multicolor visualization of X-ray radiation from red to green can be facilely achieved, providing a new class of scintillating materials with continuous color tunability that can be customized for desired purposes. Moreover, these lanthanide–organic framework based scintillators exhibit excellent radiation resistance and humidity stability, in comparison with the state of the art and commercially-available X-ray scintillator, CsI:Tl. [ABSTRACT FROM AUTHOR]

Cooperative performance of mixed-valent Eu2+/Eu3+ in single-compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu2+ oxidation. Using the tunable nature of the metal-ion nodes in metal-organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu2+/Eu3+ with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic- and sensitized-emissions of Eu2+ and Eu3+, and long-lived luminescence from charge transfer. Color rendering can be easily achieved by fine-tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu2+/Eu3+ emissions provides outstanding properties for applications as self-calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb3+ into the MOFs results in white light, utilizing all Eu2+,Tb3+, and Eu3+ emissions in a single crystalline lattice. [ABSTRACT FROM AUTHOR]

Abstract We report here the investigation of using a luminescent europium organic framework, [Eu 2 (MTBC)(OH) 2 (DMF) 3 (H 2 O) 4 ]·2DMF·7H 2 O (denoted as compound 1), for detecting of both Cu2+ and UO 2 2+ with high sensitivity. Based on the spectroscopy analysis, compound 1 could selectively respond to Cu2+ and UO 2 2+ ions among other selected monovalent, divalent, trivalent metal cations based on a turn-off mechanism. The detection limit of compound 1 towards Cu2+ ion was as low as 17.2 μg/L, which is much lower than the maximum tolerable concentration of Cu2+ in drinking water (2 mg/L) defined by United States Environmental Protection Agency. On the other hand, the detection limit towards UO 2 2+ ions is 309.2 μg/L, which could be used for detecting uranium in relative severely contaminated areas. The concentration-dependent luminescence intensity evolution process could be fully understood by the absorption kinetics and isotherm investigations. Furthermore, the quenching mechanism was elucidated by the UV-vis, excitation, luminescence, and lifetime studies. Compound 1 , as the first MOF based luminescence probe for both Cu2+ and UO 2 2+ ions, provides insight into developing MOF-based multifunctional sensors for both nonradioactive and radioactive elements. Graphical abstract fx1 Highlights • A new lanthanide metal organic framework was used for both radioactive UO 2 2+ and nonradioactive Cu2+ detection. • The detection limits toward UO 2 2+ and Cu2+ are 17.2 ppb and 309.2 ppb respectively. • The material could be used for directly detecting UO 2 2+ and Cu2+ contamination in a wide concentration range. • The detection mechanism was systematically investigated by bath experiments, spectroscopy and lifetime studies. [ABSTRACT FROM AUTHOR]