State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin 300071, China.
Anal Chem. 2021 Feb 23;93(7):3559-3566. doi: 10.1021/acs.analchem.0c05040. Epub 2021 Feb 11.
Sensitivity, selectivity, visible detection, and rapid response are the main concerns for an analytical method. Herein, we reported a metal-organic framework (MOF)-based ratiometric fluorescence detection strategy for hypochlorous acid (HClO). The MOF was prepared with dual ligands, 2-aminoterephthalic acid (BDC-NH) and dipicolinic acid (DPA) and Eu ions as a metal node, denoted as Eu-BDC-NH/DPA. The dual-ligand strategy realized the dual emission for ratiometric sensing and visual detection, adjusted the size and morphology of MOFs to obtain a good dispersion for a rapid response, and provided an amino group for the special recognition of HClO. Thus, the MOF exhibited a dual emission derived from BDC-NH and Eu ions at 433 and 621 nm, respectively, under a single excitation at 270 nm. A hydrogen bond forms between an -NH group and HClO to weaken the blue fluorescence at 433 nm, while the antenna effect emission from Eu ions kept stable, so ratiometric sensing was realized with an easy-to-differentiate color change for visible detection. The ratiometric sensing showed a self-calibration effect and reduced the background. Thus, the high sensitivity, visual detection, low detection limit (37 nM), and short response time (within 20 s) for the detection of HClO were realized with the MOF as a probe. The analysis of real samples demonstrated the practical application of the MOF for HClO. The introduction of mixed ligands is an effective strategy to regulate the emission behaviors of MOFs for the improved analytical performance.
灵敏度、选择性、可见检测和快速响应是分析方法的主要关注点。在此，我们报道了一种基于金属有机骨架（MOF）的比率荧光检测次氯酸（HClO）的策略。该 MOF 由双配体 2-氨基对苯二甲酸（BDC-NH）和二吡啶酸（DPA）以及 Eu 离子作为金属节点制备，记为 Eu-BDC-NH/DPA。双配体策略实现了比率传感和可视化检测的双发射，调整了 MOF 的尺寸和形态以获得快速响应的良好分散性，并提供了一个氨基用于 HClO 的特殊识别。因此，MOF 在 270nm 单激发下分别在 433nm 和 621nm 处表现出源自 BDC-NH 和 Eu 离子的双发射。NH 基团与 HClO 之间形成氢键，从而削弱了 433nm 处的蓝色荧光，而 Eu 离子的天线效应发射保持稳定，因此实现了比率传感，具有易于区分的颜色变化进行可见检测。比率传感具有自校准效应并降低了背景。因此，MOF 作为探针实现了对 HClO 的高灵敏度、可见检测、低检测限（37 nM）和短响应时间（20 秒内）。实际样品的分析证明了 MOF 在 HClO 分析中的实际应用。混合配体的引入是调节 MOF 发射行为以提高分析性能的有效策略。
