Tuning the Formations of Metal鈥揙rganic Frameworks by Modification of Ratio of Reactant, Acidity of Reaction System, and Use of a Secondary Ligand

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• 作者：Qian Gao ; Ya-Bo Xie ; Jian-Rong Li ; Da-Qiang Yuan ; Audrey A. Yakovenko ; Ji-Hong Sun ; Hong-Cai Zhou
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：January 1, 2012
• 年：2012
• 卷：12
• 期：1
• 页码：281-288
• 全文大小：1061K
• 年卷期：v.12,no.1(January 1, 2012)
• ISSN：1528-7505

文摘

Four porous coordination networks (PCNs), {[Zn₃O(H₂O)₃(adc)₃]路2(C₂H₆NH₂)路2(DMF)路3(H₂O)}_n (PCN-131), Zn₂(DMA)₂(adc)₂]路2(DMA)}_n (PCN-132), {[Zn₃O(DMF)(adc)₃(4,4鈥?bpy)]路2(C₂H₆NH₂)路S}_n (PCN-131鈥?/b>), and {[Zn(adc)(4,4鈥?bpy)_0.5]路S}_n (PCN-132鈥?/b>), have been synthesized by the assembly of anthrancene-9,10-dicarboxylic acid (H₂adc) with Zn(II) under different reaction conditions, including modifications of reactant ratio, acidity variations, and the use of a secondary ligand. Single-crystal X-ray diffraction studies reveal that PCN-131, obtained from the dimethylformamide (DMF) solution under acid condition, has a three-dimentional (3D) framework structure with one-dimensional (1D) honeycomb channels. PCN-132 isolated from dimethylacetamide (DMA) solution without adding acid in synthesis is a two-dimensional (2D) layer compound. By employing 4,4鈥?bipyridyl (4,4鈥?bpy) as a secondary ligand, PCN-131鈥?/b> and PCN-132鈥?/b> were synchronously synthesized as a mixture outcome with more PCN-131鈥?/b> than PCN-132鈥?/b>. In PCN-131鈥?/b>, 4,4鈥?bpy acting as a secondary ligand is arranged inside the honeycomb channel of the 3D PCN-131, resulting in an effective improvement of thermal stability of the network, while in PCN-132鈥?/b>, 4,4鈥?bpy ligands link 2D layers of PCN-132 to form a pillared-layer 3D framework. Gas adsorption has been performed for selected materials. The results show that the framework of PCN-131 is thermally unstable after removing the solvent molecules coordinated to their metal sites. While PCN-131鈥?/b> is stable for gas uptake, with an evaluated Langmuir surface area of 199.04 m² g^鈥?, it shows a selective adsorption of CO₂ over CH₄.