p-tert-Butylcalix[4]arene Derivatives Containing Azathiol Receptors and Their Recognition towards Hg(II) |
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Authors: | Korakot Navakun Thawatchai Tuntulani Vithaya Ruangpornvisuti |
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Institution: | (1) Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand |
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Abstract: | 25,27(2,2'-bis(ethoxybenzyl))-1,9-diimine-3,7-dithianonane-p-tert-butylcalix4]arene (3),25,27(4,4'-bis(ethoxybenzyl))-1,9-diimine-3,7-dithianonane-p-tert-butylcalix4]arene (4),25,27(2,2'-bis(ethoxybenzyl))-1,8-diimine-3,6-dithianonane-p-tert-butylcalix4]arene (5) and25,27(4,4'-bis(ethoxybenzyl))-1,8-diimine-3,6-dithianonane-p-tert-butylcalix4]arene (6) havebeen synthesized by condensation reactions between25,27(2,2'-bis(ethoxybenzaldehyde))-p-tert-butylcalix4]arene (1) and25,27(4,4'-bis(ethoxybenzaldehyde))-p-tert-butylcalix4]arene (2) and appropriateamines. Reduction of 3 and 4 withNaBH4 and subsequent protonation byHCl/CH3OH resulted in25,27(2,2'-bis(ethoxybenzyl))-1,9-diaza-3,7-dithianonane-p-tert-butylcalix4]arenedihydrogenchloride (7) and25,27(4,4'-bis(ethoxybenzyl))-1,9-diaza-3,7-dithianonane-p-tert-butylcalix4]arenedihydrogenchloride (8), respectively. Complexation studies of 7 and 8 withZn(II), Cd(II) and Hg(II) ions were carried out bypotentiometric titration. Compounds 7 and8 selectively form 1 : 1 complexes with Hg(II), andtheir stability constants (log Ks) were estimated tobe 4.47 ± 0.08 and 3.20 ± 0.13, respectively. From spiecies distribution plots, 7 and 8were found to form the highest amount of 1 : 1 complexes with Hg(II) at pH 8.7 and 9.1, respectively. |
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Keywords: | azathiol p-tert-butylcalix[4]arene potentiometric titration heavy metal ion complexing agents |
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