Primary aromatic amines (PAAs), as a class of persistent and highly toxic organic pollutants, have been posing a great threat to human health and the environment. Therefore, the design and preparation of a highly sensitive and selective luminescent probe to detect PAAs among various amines are important but challenging. In this work, by introducing electron-deficient monomer 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzaldehyde (BTDD) with an aggregation-caused quenching behavior into the 2D framework, fluorescent ultrathin covalent triazine framework (F-CTF) nanosheets were constructed. Compared with the aggregated BTDD monomer, the obtained F-CTF-3 nanosheet shows much higher fluorescence quantum yield due to the BTDD fragment being well dispersed in the 2D framework. The F-CTF-3 nanosheet exhibits high stability, high porosity, and high fluorescence performance and has a rich electron-deficient unit in the pore channel, making it an ideal platform for sensing electron-rich PAA molecules. In fact, the F-CTF-3 nanosheet shows high sensitivity and selectivity for PAA detection by fluorescence quenching, among various amines, covering some classic aliphatic amines, heterocyclic amines, secondary aromatic amines and tertiary aromatic amines. To the best of our knowledge, it is the first reported fluorescent sensor for selective sensing of PAAs among various amines. Moreover, F-CTF-3 exhibits unprecedented low detection limits of 11.7 and 1.47 nM toward phenylamine (PA) and p-phenylenediamine (PDA), respectively, surpassing all the reported fluorescent sensors. The combination of experimental analysis and density functional theory (DFT) calculations demonstrates that the unique PAA detection performance of F-CTF-3 can be attributed to the static quenching process, which is confirmed by the formation of a ground-state fluorescence-quenched complex on account of the hydrogen bonding interactions between F-CTF-3 and PAAs. This work not only provides a thiadiazole-based 2D fluorescent organic framework nanosheet, but also an excellent fluorescent sensor with unexpected sensitivity and selectivity for PAA detection.

中文翻译：

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基于噻二唑的共价三嗪骨架纳米片，可在多种胺中进行高度选择性和灵敏的伯芳族胺检测

伯芳香胺（PAA）作为一类持久的剧毒有机污染物，已经对人类健康和环境构成了巨大威胁。因此，设计和制备高灵敏度和选择性的发光探针以检测各种胺中的PAA固然重要，但却具有挑战性。在这项工作中，通过引入缺电子单体4,4'-（苯并[ c具有[2,2]骨架的聚集引起的猝灭行为的] [1,2,5]噻二唑-4,7-二基）二苯甲醛（BTDD），构建了荧光超薄共价三嗪骨架（F-CTF）纳米片。与聚集的DDDD单体相比，由于BTDD片段很好地分散在2D骨架中，因此获得的F-CTF-3纳米片显示出更高的荧光量子产率。F-CTF-3纳米片具有高稳定性，高孔隙率和高荧光性能，并且在孔道中具有丰富的电子缺陷单元，使其成为检测富含电子的PAA分子的理想平台。实际上，F-CTF-3纳米片在各种胺中显示出通过荧光猝灭检测PAA的高灵敏度和选择性，涵盖了一些经典的脂肪族胺，杂环胺，仲芳族胺和叔芳族胺。据我们所知，它是第一个报道的用于选择性检测各种胺中PAA的荧光传感器。此外，F-CTF-3对苯胺（PA）和苯胺（PA）的检测限空前低，分别为11.7和1.47 nM。对苯二胺（PDA）分别超过了所有报道的荧光传感器。实验分析和密度泛函理论（DFT）计算的结合表明，F-CTF-3独特的PAA检测性能可以归因于静态猝灭过程，这可以通过形成基态荧光猝灭复合物来证实。由于F-CTF-3和PAA之间存在氢键相互作用。这项工作不仅提供了基于噻二唑的二维荧光有机框架纳米片，而且还提供了一种出色的荧光传感器，具有出乎意料的灵敏性和对PAA检测的选择性。