Ion vs. ion pair receptor: NMR and DFT study of the interaction of Thallium and Cesium ions and ion pairs with meso-octamethylcalix[4]pyrrole

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• 作者：Jaroslav K艡í ; 啪^a ; ^{kriz@imc.cas.cz} ; Ji艡í ; Dybal^a ; Emanuel Makrlí ; k^b ; Zde艌ka Sedlá ; ková ; ^a
• 关键词：Calix[4]pyrrole ; Thallium ion receptor ; Cesium bromide receptor ; NMR ; DFT
• 刊名：Chemical Physics
• 出版年：2012
• 期刊代码：18_03010104
• 类别：ch
• 出版时间：25 May, 2012
• 卷：400
• 期：Complete
• 页码：19-28
• 文件大小：2558 K

摘要

Binding interaction of Tl⁺, Cs⁺, Li⁺Br^{鈭?/sup>, and Cs+Br鈭?/sup> with meso-octamethylcalix[4]pyrrole (boldFont">1) in nitrobenzene-d₅ was studied using 1H, 13C, 7Li, and 133Cs NMR spectroscopy and DFT quantum-chemical calculations. Although originally declared as typical anion and ion pair receptor, boldFont">1 is shown to bind fairly strongly Tl+ cations (equilibrium constant K = 1600 卤 80 mol鈭? L鈭?). The binding of Cs+ is much weaker (K = 370 卤 18 mol鈭? L鈭?). Neither of these cations invert the conformation of boldFont">1. Li+Br鈭?/sup> binds to boldFont">1 (K = 1790 卤 160 mol鈭? L鈭?) forming at least four energetically close complexes without much change in its conformation. Cs+ Br鈭?/sup> prepared in situ from Li+Br鈭?/sup> and the cesium salt of dicarbollyl cobaltate in the presence of boldFont">1 binds strongly to boldFont">1 (K = 103514 卤 4000 mol鈭? L鈭?, log K = 5.015) in spite of the slight competition of Li+ ions. The cooperative binding of Cs+ and Br鈭?/sup> ions is shown, in accord with a recent suggestion in literature, to invert the natural conformation of boldFont">1, the four NH groups binding to Br鈭?/sup> by hydrogen bonds and the aromatic rings forming a cup binding the embedded Cs+ by its interaction with the 蟺 electron orbitals.}