DFT study of caesium ion complexation by cucurbit[n]urils (n=5-7)
DFT study of caesium ion complexation by cucurbit[n]urils (n=5-7)
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DOI：
10.1039/c2dt32180g
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发表时间：
2013-01-01
影响因子：
4
通讯作者：
Pichierri, Fabio
中科院分区：
文献类型：
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作者：
Pichierri, Fabio
利用密度泛函理论（DFT）计算和现有的晶体学数据，我们研究了水合Cs+离子与南瓜形葫芦脲大环CB[n] （n = 5-7）的结合。计算表明，除了铯离子与羰基连接的入口之间的相互作用外，配位水分子与大环之间建立的氢键也有助于整体的结合亲和力。尽管其他碱金属离子竞争与铯的结合，但相对较小的与水-铯+键相关的相互作用能可能有利于铯水离子的部分脱水。在大环的腔内包含一个水分子或一个氯阴离子，由于在配合物中分别建立了额外的离子偶极子或离子相互作用，从而增强了Cs+的结合。使用葫芦脲大环从水溶液中隔离铯离子的一个优点是可以通过羰基连接的入口结合两个水合金属离子，从而形成1:2配合物。
Using density functional theory (DFT) calculations and the available crystallographic data we have investigated the binding of hydrated Cs+ ions to the pumpkin-shaped cucurbituril macrocycles, CB[n] with n = 5-7. The calculations indicate that besides the interactions between caesium ions and the carbonyl-laced portals, also the hydrogen bonds established between the coordinated water molecules and the macrocycle do contribute to the overall binding affinity. Although the other alkali metal ions compete for binding with caesium, the partial dehydration of the caesium aqua ions is likely favoured by the relatively small interaction energy associated with the water-Cs+ bond. The inclusion inside the macrocycle's cavity of either one water molecule or one chloride anion enhances the binding of Cs+ due to the additional ion-dipole or ion-ion interactions, respectively, established within the complexes. An advantage in using cucurbituril macrocycles for the sequestration of caesium ions from an aqueous solution is the possibility of binding two hydrated metal ions by the carbonyl-laced portals thereby forming 1 : 2 complexes.