KCS Publications

HOME > Search > Browsing(BKCS) > Archives

Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 25, Number 5
BKCSDE 25(5)
May 20, 2004

Title	An NMR Study on Complexation of Cesium Ion by p-tert-Butylcalix[6]arene Ethyl Ester
Author	Kee-Choo Chung, Hyun Namgoong, Jo Woong Lee*
Keywords	NMR, Calix[6]arene, Cesium, Chemical exchange
Abstract	Complexation of cesium ion by p-tert-butylcalix[6]arene ethyl ester was studied by NMR spectroscopy in nonpolar CDCl₃ and polar acetone-d6 and the results were compared with each other. Analysis of temperature dependent ¹H spectra and titration curves reveals that both solvents result in a 1 : 1 cone-form complex with nonpolar CDCl₃ yielding a more tightly bound one than acetone-d6. Unexpectedly, at very low temperature, we have found that two phenyl ring proton peaks of equal intensity appear both in CDCl₃ and in acetone-d₆ solution which gradually collapse and eventually coalesce into a single line as temperature is raised. This observation could be interpreted in terms of the chemical exchange through direct and/or indirect interconversion between two equivalent conformations possible the complex in both solvents over the temperature range observed. And broadening of ¹³³Cs (I = 7/2) nmr line with increasing temperature has also been observed, indicating the exchange of ¹³³Cs ion between the complex and the solvent. From numerical fitting of lineshape changes for one-dimensional ¹H and ¹³³Cs spectra, the exchange rate constants and other relevant parameters for this conformational interconversion and the complex-solvent exchange were deduced.
Page	609 - 0
Full Text	PDF

How to access to the WOL for The Bulletin of the Korean Chemical Society ?

The Bulletin of the Korean Chemical Society will be co-published with Wiley-VCH from 2015 towards. The online version of the Journal will thus be available on Wiley Online Library, Wiley(-VCH)'s global online platform.

KCS members can get a free online access to the Bulletin of the Korean Chemical Society in WOL.

Free Access to WOL