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, <b>NENU-522</b>, 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, <b>Ln</b>^<b>3+</b><b>@NENU-522</b> can emit white light by encapsulating different molar ratios of Eu³⁺ and Tb³⁺ ions. Additionally, <b>Tb</b>^<b>3+</b><b>@NENU-522</b> 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, <b>Tb</b>^<b>3+</b><b>@NENU-522</b> displays high selectivity and recyclability in the detection of nitroaromatic explosives