State Key Laboratory of Sensor Technology, and Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, P. R. China.
Dalton Trans. 2020 Dec 28;49(48):17737-17744. doi: 10.1039/d0dt03781h. Epub 2020 Nov 25.
Recently, exploring new luminescent metal-organic frameworks (LMOFs) to selectively detect nitro-aromatic compounds (NACs) has been a hot topic of research. Simultaneously, it is still a challenging issue to understand the sensing mechanism of luminescent MOFs interacting with NACs at the molecular level. In this work, highly fluorescent Sc-tetracarboxylate frameworks (Sc-EBTC) have been successfully synthesized through a solvothermal method. The as-prepared Sc-EBTC crystals have good thermal stability, chemical stability as well as strong fluorescence (λ = 320 nm and λ = 400 nm), and they can detect various NACs rapidly (as short as 30 s), selectively and efficiently by the "turn-off" fluorescence mechanism. The detection limits of Sc-EBTC toward 2,4-DNP and 4-NP are quantified to be 5.71 ppb and 6.26 ppb, respectively. Furthermore, to better understand the sensing mechanism, we attempt to use solid-state NMR and X-ray photoelectron spectroscopy to vividly characterize the charge transfer caused by the interaction between NAC molecules and the MOF at the molecular level. Additionally, test strips were made successfully for the practical detection of the NACs. This study demonstrates that the MOF constructed from the HEBTC ligands might be a promising candidate for the detection of trace NACs.
最近，探索新的发光金属-有机骨架（LMOFs）以选择性检测硝基芳香族化合物（NACs）一直是研究的热点。同时，在分子水平上理解发光 MOFs 与 NACs 相互作用的传感机制仍然是一个具有挑战性的问题。在这项工作中，通过溶剂热法成功合成了高荧光的 Sc-四羧酸骨架（Sc-EBTC）。所制备的 Sc-EBTC 晶体具有良好的热稳定性、化学稳定性和强荧光（λ=320nm 和 λ=400nm），它们可以通过“关闭”荧光机制快速（最短 30s）、选择性和有效地检测各种 NACs。Sc-EBTC 对 2,4-DNP 和 4-NP 的检测限分别定量为 5.71ppb 和 6.26ppb。此外，为了更好地理解传感机制，我们尝试使用固态 NMR 和 X 射线光电子能谱在分子水平上生动地描绘 NAC 分子与 MOF 之间相互作用引起的电荷转移。此外，还成功制备了用于实际检测 NACs 的测试条。这项研究表明，由 HEBTC 配体构建的 MOF 可能是检测痕量 NACs 的有前途的候选材料。
