Interaction of Cesium Ions with Calix[4]arene-bis(t-octylbenzo-18-crown-6): NMR and Theoretical Study

详细信息    查看全文

• 作者：Jaroslav Kr虒i&#769 ; ž ; Jir虒i&#769 ; Dybal ; Emanuel Makrli虂k ; Petr Van虒ura ; Bruce A. Moyer
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：June 16, 2011
• 年：2011
• 卷：115
• 期：23
• 页码：7578-7587
• 全文大小：1053K
• 年卷期：v.115,no.23(June 16, 2011)
• ISSN：1520-5207

文摘

Using ¹H, ¹³C, and ¹³³Cs NMR spectra, it is shown that calix[4]arene-bis(t-octylbenzo-18-crown-6) (L) forms complexes with one (L路Cs⁺) and two (L路2Cs⁺) Cs⁺ ions offered by cesium bis(1,2-dicarbollide) cobaltate (CsDCC) in nitrobenzene-d₅. The ions interact with all six oxygen atoms in the crown-ether ring and the 蟺 electrons of the calixarene aromatic moieties. According to extraction technique, the stability constant of the first complex is log 尾_nb(L路Cs⁺) = 8.8 卤 0.1. According to ¹³³Cs NMR spectra, the value of the equilibrium constant of the second complex is log K_nb⁽²⁾(L路2Cs⁺) = 6.3 卤 0.2, i.e., its stabilization constant is log 尾_nb(L路2Cs⁺) = 15.1 卤 0.3. Self-diffusion measurements by ¹H pulsed-field gradient (PFG) NMR combined with density functional theory (DFT) calculations suggest that one DCC^{鈥?/sup> ion is tightly associated with L路Cs+, decreasing its positive charge and consequently stabilizing the second complex, L路2Cs+. Using a saturation-transfer 133Cs NMR technique, the correlation times 蟿_ex of chemical exchange between L路Cs+ and L路2Cs+ as well as between L路2Cs+ and free Cs+ ions were determined as 33.6 and 29.2 ms, respectively.}