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p>ap>p> ; p>p>kriz@imc.cas.czp> ; Ji艡í ; Dybalp>ap> ; Emanuel Makrlí ; kp>bp> ; Zde艌ka Sedl&aacute ; kov&aacute ; p>ap>
• 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 Tlp>+p>, Csp>+p>, Lip>+p>Brp>鈭?/sup>, and Csp>+p>Brp>鈭?/sup> with meso-octamethylcalix[4]pyrrole (1) in nitrobenzene-d₅ was studied using p>1p>H, p>13p>C, p>7p>Li, and p>133p>Cs NMR spectroscopy and DFT quantum-chemical calculations. Although originally declared as typical anion and ion pair receptor, 1 is shown to bind fairly strongly Tlp>+p> cations (equilibrium constant K = 1600 卤 80 molp>鈭?p> Lp>鈭?p>). The binding of Csp>+p> is much weaker (K = 370 卤 18 molp>鈭?p> Lp>鈭?p>). Neither of these cations invert the conformation of 1. Lip>+p>Brp>鈭?/sup> binds to 1 (K = 1790 卤 160 molp>鈭?p> Lp>鈭?p>) forming at least four energetically close complexes without much change in its conformation. Csp>+p> Brp>鈭?/sup> prepared in situ from Lip>+p>Brp>鈭?/sup> and the cesium salt of dicarbollyl cobaltate in the presence of 1 binds strongly to 1 (K = 103514 卤 4000 molp>鈭?p> Lp>鈭?p>, log K = 5.015) in spite of the slight competition of Lip>+p> ions. The cooperative binding of Csp>+p> and Brp>鈭?/sup> ions is shown, in accord with a recent suggestion in literature, to invert the natural conformation of 1, the four NH groups binding to Brp>鈭?/sup> by hydrogen bonds and the aromatic rings forming a cup binding the embedded Csp>+p> by its interaction with the 蟺 electron orbitals.