A Schiff base functionalized Cu(II)-based metal–organic framework (MOF) denoted as Cu-L, was developed via a solvothermal method using low-cost starting material, i.e., Schiff base linker, 4,4'-(hydrazine-1,2-diylidenedimethylylidene)dibenzoic acid (L). Good crystallinity and thermal stability of synthesized Cu-L was confirmed by the crystallographic and thermogravimetric studies. An excellent photoluminescent properties of Cu-L ensure their suitability for the ultrafast detection of Fe³⁺ ions and nitrobenzene via a turn-off quenching response. The remarkable sensitivity of Cu-L towards Fe³⁺ ions and nitrobenzene was certified by the low limit of detection (LOD) of 47 ppb and 0.004 ppm, respectively. With incorporated free azine groups, this MOF could selectively capture Fe³⁺ ions and nitrobenzene in aqueous solution. The plausible mechanistic pathway for the quenching in the fluorescence intensity of the Cu-L in the presence of Fe³⁺ ions and nitrobenzene have been explained in detail through the density functional theory calculations, photo-induced electron transfer (PET), fluorescence resonance energy transfer (FRET), and competitive energy adsorption. This present study open a new avenue to synthesize novel crystalline MOF-based sensing materials from cheap Schiff base linkers for fast sensing of toxic pollutants.

Graphical Abstract

中文翻译：

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具有 Lewis Basic Sc​​hiff 碱基的发光 Cu(II)-MOF，用于高选择性和灵敏地检测 Fe3+ 离子和硝基苯

一种席夫碱功能化的基于 Cu(II) 的金属有机骨架 (MOF)，表示为 Cu-L，通过溶剂热法使用低成本起始材料开发，即席夫碱连接剂、4,4'-(肼- 1,2-二亚甲基亚甲基)二苯甲酸(L)。结晶学和热重分析证实了合成的 Cu-L 具有良好的结晶度和热稳定性。Cu-L 出色的光致发光特性确保它们适用于通过关断猝灭响应超快检测 Fe ³⁺离子和硝基苯。Cu-L对Fe ^{3+的显着敏感性}离子和硝基苯的检测下限 (LOD) 分别为 47 ppb 和 0.004 ppm。通过引入游离吖嗪基团，该 MOF 可以选择性地捕获水溶液中的Fe ^{3+离子和硝基苯。}通过密度泛函理论计算、光诱导电子转移 (PET)、荧光共振能量，详细解释了在Fe ³⁺离子和硝基苯存在下 Cu-L 荧光强度猝灭的可能机制途径转移 (FRET) 和竞争性能量吸附。本研究开辟了一条新途径，可以从廉价的席夫碱接头合成新型结晶 MOF 传感材料，用于快速传感有毒污染物。

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