Crystallographic investigation into the self-assembly, guest binding, and flexibility of urea functionalised metal-organic frameworks
Crystallographic investigation into the self-assembly, guest binding, and flexibility of urea functionalised metal-organic frameworks
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DOI：
10.1080/10610278.2017.1370095
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发表时间：
2018-09
影响因子：
3.3
通讯作者：
Ross J. Marshall;Jake McGuire;Claire Wilson;Ross S. Forgan
中科院分区：
文献类型：
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作者：
Ross J. Marshall;Jake McGuire;Claire Wilson;Ross S. Forgan
在金属有机框架中引入氢键功能可以增强客体结合和激活，但是连接子的灵活性和配体间氢键的结合通常会导致产生不需要的结构，而功能被掩盖。在本文中，我们描述了三种材料的自组装，其中Cd2+， Ca2+和Zn2+由N，N + -双（4-羧基苯基）尿素连接，并研究了尿素单元对结构形成，不寻常的二级构建单元的产生，结构灵活性和客结合的影响。在DMF交换CS2时，通过单晶到单晶的转变来探测Zn MOF的灵活性，表明[zn40o (RCO2)6]簇对溶剂化的不稳定性使得尿素连接物在MOF呼吸时采用扭曲的构象，甚至可以在不影响整体拓扑结构的情况下从反式/反式构象旋转到反式/顺式构象。研究结果对了解mof的水解稳定性机理和制备多相有机催化剂具有重要意义。
Abstract Introduction of hydrogen bond functionality into metal-organic frameworks can enhance guest binding and activation, but a combination of linker flexibility and interligand hydrogen bonding often results in the generation of unwanted structures where the functionality is masked. Herein, we describe the self-assembly of three materials, where Cd2+, Ca2+, and Zn2+ are linked by N,Nʹ-bis(4-carboxyphenyl)urea, and examine the effect of the urea units on structure formation, the generation of unusual secondary building units, structural flexibility, and guest binding. The flexibility of the Zn MOF is probed through single-crystal to single-crystal transformations upon exchange of DMF guests for CS2, showing that the lability of the [Zn4O(RCO2)6] cluster towards solvation enables the urea linkers to adopt distorted conformations as the MOF breathes, even facilitating rotation from the trans/trans to the trans/cis conformation without compromising the overall topology. The results have significant implications in the mechanistic understanding of the hydrolytic stability of MOFs, and in preparing heterogeneous organocatalysts.