Two 3D Cd(II) Metal–Organic Frameworks Linked by Benzothiadiazole Dicarboxylates: Fantastic S@Cd6 Cage, Benzothiadiazole Antidimmer, and Dual Emission

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• 作者：Qing Cheng ; Xiao Han ; Yue Tong ; Chao Huang ; Jie Ding ; Hongwei Hou
• 刊名：Inorganic Chemistry
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：56
• 期：3
• 页码：1696-1705
• 全文大小：580K
• ISSN：1520-510X

文摘

On the basis of the same benzothiadiazole (BTD) ligand 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H₂L), two new isomers of three-dimensional (3D) BTD-derived Cd(II) metal–organic frameworks 1-2 {[S@Cd₆L₆]·xH₂O}_n were obtained by the different solvothermal reactions, which were structurally similar. Surprisingly, structural analyses reveal that in 1 or 2, one free sulfur atom was fixed in a Cd(II) cluster cage by strong intermolecular interaction to form the secondary building unit (SBU) S@Cd₆. Each SBU S@Cd₆ is connected by six L^2– ligands and further extended into the 3D porous framework. In this work, the BTD antidimmer was evidenced by structural analysis and photophysical study. Furthermore, either 1 or 2 showed the uncommon dual emission, while only one emission was observed in the solution of ligand H₂L. The dual-emission mechanism was also realized by the structural analysis and photophysical study. Interestingly, although there is slight difference in structure (regular octahedral cage in 1 and slightly distorted octahedral cage in 2), the changes in N₂ adsorption capability and photophysical performance between 1 and 2 are obvious, where 2 shows smaller Brunauer–Emmett–Teller surface area, broader absorption of antidimmer, and longer dual-emission lifetimes. Interestingly, either 1 or 2, the dual emission was clearly red-shifted by increasing the solvent polarity or the acidity of ambience, respectively.