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Cationic Metal–Organic Frameworks Based on Linear Zwitterionic Ligands for Cr2O72– and Ammonia Sensing
Crystal Growth & Design ( IF 3.8 ) Pub Date : 2020-04-02 , DOI: 10.1021/acs.cgd.0c00247
Zhiyuan Li 1 , Wenyan Cai 1 , Xiaoman Yang 1 , Aling Zhou 1 , Yi Zhu 1 , Huan Wang 1 , Xin Zhou 1 , Kecai Xiong 1, 2 , Qingfu Zhang 3 , Yanli Gai 1, 2
Affiliation  

A series of cationic lanthanide-based metal–organic frameworks (MOFs), {[Ln3(bcbp)3(NO3)7]·NO3·ClO4}n (Ln = Tb (1), Gd (2), Eu (3); H2bcbpCl2 = 1,1′-bis(4-carboxyphenyl)(4,4′-bipyridinium) dichloride), have been synthesized under solvothermal conditions and structurally characterized. Single-crystal X-ray diffraction analyses reveal that compounds 13 are isostructural, in which Ln3-SBUs (SBUs = secondary building units) are connected with six adjacent Ln3-SBUs by six protonated bcbp ligands, leading to cationic lanthanide-based metal–organic frameworks. In addition, the counteranions (nitrate anions and perchlorate anions) reside in the frameworks via weak C–H···O hydrogen bonds. Furthermore, Eu-MOF displays strong red luminescence, which is further proven to be a highly selective and sensitive luminescent sensor toward Cr2O72– with a high quenching coefficient and low detection limit. Interestingly, Eu-MOF is also sensitive to ammonia and exhibits a rapid color change from yellow to blue-gray that can be distinguished by the naked eye when it is exposed to ammonia vapor. The UV–vis, IR, Raman, and EPR data reveal that the color change can be ascribed to an electron-transfer process and the radical generation caused by the nucleophilic attack of ammonia molecules.

中文翻译:

基于线性两性离子配体的Cr 2 O 7 2–和氨感测的阳离子金属有机框架

一系列基于阳离子镧系元素的金属有机骨架(MOF),{[Ln 3(bcbp)3(NO 37 ]·NO 3 ·ClO 4 } n(Ln = Tb(1),Gd(2), Eu(3); H 2 bcbpCl 2 = 1,1'-双(4-羧苯基)(4,4'-联吡啶鎓二氯化物),已在溶剂热条件下合成并进行了结构表征。单晶X射线衍射分析表明,化合物1 - 3是同构的,其中LN 3-SBU(SBU =二级建筑单元)通过六个质子化的bcbp配体与六个相邻的Ln 3 -SBU连接,从而形成基于阳离子镧系元素的金属有机骨架。此外,抗衡阴离子(硝酸根阴离子和高氯酸根阴离子)通过弱的C–H··O氢键存在于骨架中。此外,Eu-MOF显示出很强的红色发光,这进一步证明是对Cr 2 O 7 2–的高度选择性和灵敏的发光传感器。淬灭系数高,检出限低。有趣的是,Eu-MOF对氨也很敏感,并且显示出从黄色到蓝灰色的快速颜色变化,当暴露于氨气时,肉眼可以辨别出这种颜色。UV-vis,IR,Raman和EPR数据表明,颜色变化可归因于电子转移过程以及氨分子的亲核攻击导致的自由基生成。
更新日期:2020-04-02
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