Modification of Extended Open Frameworks with Fluorescent Tags for Sensing Explosives: Competition between Size Selectivity and Electron Deficiency
Modification of Extended Open Frameworks with Fluorescent Tags for Sensing Explosives: Competition between Size Selectivity and Electron Deficiency
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DOI：
10.1002/chem.201302455
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发表时间：
2014-02-17
影响因子：
4.3
通讯作者：
Mukherjee, Partha Sarathi
中科院分区：
文献类型：
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作者：
Gole, Bappaditya;Bar, Arun Kumar;Mukherjee, Partha Sarathi
利用带有芳香标签的配体合成了三种新的富电子金属有机骨架（MOF-1-MOF-3）。所选择的芳香族标记物的关键作用是增强发光MOFs的电子密度。单晶X射线结构显示，这些MOFs形成三维多孔网络，芳香标签向内突出到孔中。这些高发光的富电子MOFs已被成功地用于检测爆炸性硝基芳香化合物（NAC）的荧光猝灭的基础上。尽管所有制备的MOFs都可以作为NAC的传感器，但与2，4，6-三硝基甲苯（TNT）和1，3，5-三硝基苯（TNB）相比，MOF-1和MOF-2对4-硝基甲苯（4-NT）和2，4-二硝基甲苯（DNT）表现出上级灵敏度。另一方面，M0 F-3示出了根据基板的电子缺陷的灵敏度的顺序。为了理解这种异常行为，我们彻底分析了与这些相互作用相关的稳态和时间分辨荧光猝灭。静态Stern-Volmer常数（K-S）以及碰撞常数（K-C）的测定表明，M0 F-1和M0 F-2与4-NT相比具有更高的K-S值，而对于M0 F-3，观察到相反的顺序。这种明显的反常现象得到了理论计算的充分证实。此外，可回收性和敏感性研究表明，这些MOFs可以重复使用多次，其对TNT溶液的敏感性为十亿分之一（ppb）水平。
Three new electron-rich metal-organic frameworks (MOF-1-MOF-3) have been synthesized by employing ligands bearing aromatic tags. The key role of the chosen aromatic tags is to enhance the -electron density of the luminescent MOFs. Single-crystal X-ray structures have revealed that these MOFs form three-dimensional porous networks with the aromatic tags projecting inwardly into the pores. These highly luminescent electron-rich MOFs have been successfully utilized for the detection of explosive nitroaromatic compounds (NACs) on the basis of fluorescence quenching. Although all of the prepared MOFs can serve as sensors for NACs, MOF-1 and MOF-2 exhibit superior sensitivity towards 4-nitrotoluene (4-NT) and 2,4-dinitrotoluene (DNT) compared to 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitrobenzene (TNB). MOF-3, on the other hand, shows an order of sensitivity in accordance with the electron deficiencies of the substrates. To understand such anomalous behavior, we have thoroughly analyzed both the steady-state and time-resolved fluorescence quenching associated with these interactions. Determination of static Stern-Volmer constants (K-S) as well as collisional constants (K-C) has revealed that MOF-1 and MOF-2 have higher K-S values with 4-NT than with TNT, whereas for MOF-3 the reverse order is observed. This apparently anomalous phenomenon was well corroborated by theoretical calculations. Moreover, recyclability and sensitivity studies have revealed that these MOFs can be reused several times and that their sensitivities towards TNT solution are at the parts per billion (ppb) level.