Discipline of Chemistry , Indian Institute of Technology (IIT) Indore , Indore , Madhya Pradesh 453552 , India.
ACS Appl Mater Interfaces. 2019 Mar 6;11(9):9042-9053. doi: 10.1021/acsami.8b20013. Epub 2019 Feb 19.
Luminescent metal-organic frameworks (LMOFs) are promising functional materials for sustainable applications, where an analyte-induced multiresponsive system with good recyclability is beneficial for detecting numerous lethal pollutants. We designed and built the dual-functionalized, three-dimensional Zn(II)-framework [Zn( bpg)( azdc)]·(DMF)·(HO) (CSMCRI-1) using an -OH group-integrated bpg linker and a -N═N- moiety containing H azdc ligand, which functions as a unique tetrasensoric fluorescent probe. The activated CSMCRI-1 (1') represents the hitherto unreported pillar-layer framework for extremely selective fluorescence quenching by nitrofurazone antibiotics as well as explosive nitro-aromatic 2,4,6-trinitrophenol, where ultrasensitive detection is achieved for both the electron-lacking analytes. Impressively, 1' represents the first ever MOF for significant fluorescence "turn-on" detection of toxic and electron-rich 4-aminophenol in the concurrent presence of isomeric analogues. Density functional theory calculations highlight the specific importance of pillar functionalization in the "turn-on" or "turn-off" responses of 1' by electronically divergent toxic organics and provide further proof of supramolecular interactions between the framework and analytes. The fluorescence intensity of 1' dramatically quenches by a trace amount of Fe ions over other competing metal ions, alongside visible colorimetric change of the framework in solid and solution phase upon Fe encapsulation. The sensing ability of 1' remains unaltered for multiple cycles toward all lethal pollutants. The sensing mechanism is attributed to both dynamic and static quenching as well as resonance energy transfer, which strongly comply with the predictions of theoretical simulations. Considering the long-term and real-time monitoring, AND as well as OR molecular logic gates are constructed based on the discriminative fluorescence response for each analyte that provides a platform to fabricate smart LMOFs with multimode logic operations.
发光金属-有机骨架（LMOFs）是可持续应用的有前途的功能材料，其中具有良好可回收性的分析物诱导的多响应系统有利于检测众多致命污染物。我们设计并构建了双功能的三维 Zn(II)骨架[Zn( bpg)( azdc)]·(DMF)·(HO)(CSMCRI-1)，使用了具有 -OH 基团的 bpg 连接体和含有 -N═N-部分的 H azdc 配体，该配体用作独特的四传感荧光探针。激活的 CSMCRI-1(1')代表了迄今为止未报道的层柱骨架，可通过硝基呋喃类抗生素和爆炸物硝基芳香族 2,4,6-三硝基苯酚对其进行极其选择性的荧光猝灭，从而对这两种缺电子分析物进行超灵敏检测。令人印象深刻的是，1'代表了第一个用于在存在异构类似物的情况下对有毒且富电子的 4-氨基酚进行显著荧光"开启"检测的 MOF。密度泛函理论计算突出了柱功能化在 1'的"开启"或"关闭"响应中对电子不同的有毒有机物的特定重要性，并提供了框架与分析物之间超分子相互作用的进一步证据。1'的荧光强度被痕量的 Fe 离子强烈猝灭，而其他竞争金属离子则猝灭，同时在固态和溶液相中，框架的可见颜色发生变化。1'对所有致命污染物的循环传感能力保持不变。传感机制归因于动态和静态猝灭以及共振能量转移，这与理论模拟的预测强烈一致。考虑到长期和实时监测，AND 以及 OR 分子逻辑门是基于每个分析物的区分荧光响应构建的，为具有多模式逻辑操作的智能 LMOFs 提供了一个平台。
