Stable Luminescent Metal–Organic Frameworks as Dual-Functional Materials To Encapsulate Ln³⁺ Ions for White-Light Emission and To Detect Nitroaromatic Explosives

A stable porous carbazole-based luminescent metal–organic framework, NENU-522, was successfully constructed. It is extremely stable in air and acidic/basic aqueous solutions, which provides the strategy for luminescent material encapsulation of Ln3+ ions with tunable luminescence for application in light emission. More importantly, Ln3+@NENU-522 can emit white light by encapsulating different molar ratios of Eu3+ and Tb3+ ions. Additionally, Tb3+@NENU-522 is found to be useful as a fluorescent indicator for the qualitative and quantitative detection of nitroaromatic explosives with different numbers of −NO2 groups, and the concentrations of complete quenching are about 2000, 1000, and 80 ppm for nitrobenzene, 1,3-dinitrobenzene, and 2,4,6-trinitrophenol, respectively. Meanwhile, Tb3+@NENU-522 displays high selectivity and recyclability in the detection of nitroaromatic explosives.本研究成功构筑了一种稳定的咔唑基多孔发光金属有机框架（metal–organic framework，MOF）材料NENU-522。该材料在空气及酸碱水溶液中均具备极佳的稳定性，为封装镧系Ln³⁺离子以制备可调谐发光材料提供了可行方案，可应用于光发射领域。更为关键的是，通过封装不同摩尔比的铕Eu³⁺与铽Tb³⁺离子，Ln³⁺@NENU-522可发射白光。此外，研究发现Tb³⁺@NENU-522可作为荧光指示剂，用于对含不同硝基（−NO₂）基团的硝基芳香族炸药进行定性与定量检测；针对硝基苯、1,3-二硝基苯及2,4,6-三硝基苯酚，其完全淬灭浓度分别约为2000 ppm、1000 ppm与80 ppm。同时，Tb³⁺@NENU-522在硝基芳香族炸药的检测中展现出优异的选择性与循环复用性能。