Dutta, Ranjan ; Ghosh, Pradyut (2012) Encapsulation of fluoride/chloride in the C3v-symmetric cleft of a pentafluorophenyl-functionalized cyanuric acid platform based tripodal amide: solid and solution-state anion-binding studies European Journal of Inorganic Chemistry, 2012 (21). pp. 3456-3462. ISSN 1434-1948
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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/ejic.20...
Related URL: http://dx.doi.org/10.1002/ejic.201200074
Abstract
A simple electron-deficient cyanuric acid based tripodal amide, 1,3,5-tris[2-(2,3,4,5,6-pentafluorobenzamido)ethyl]-1,3,5-triazinane-2,4,6-trione (L), was synthesized and characterized by NMR spectroscopy, ESI mass spectrometry, and single-crystal X-ray crystallographic studies. The binding of various anions towards L was thoroughly examined bysingle-crystal X-ray crystallography as well as solution-state isothermal titration calorimetry (ITC). The crystallographic results show that L has an unsymmetrical cleft, where the third arm is perpendicularly disposed to the other two arms. Interestingly, L upon complexation with tetrabutylammonium fluoride/chloride shows encapsulation of monotopic fluoride/chloride in the C3v-symmetric cleft by means of N–H···X (X = F–, Cl–) hydrogen-bonding interactions in complexes 1 and 2. In complex 2, the encapsulated chloride ion shows evidence of anion–π interactions with the pentafluorophenyl moiety. A detailed solution-state ITC study of L with tetrabutylammonium salts of different halides in acetonitrile showed an exothermic binding profile with 1:1 (host/guest) stoichiometry for fluoride (log Ka = 4.86 M–1), chloride (log Ka = 3.83 M–1), and bromide (log Ka = 2.97 M–1). In the case of iodide, no such binding was observed. Oxyanions like acetate and benzoate also show an exothermic binding profile with a 1:1 (host/guest) binding pattern, whereas other oxyanions like phosphate, sulfate, and nitrate failed to exhibit a 1:1 binding model. The presence of [L(X)]– (X = F, Cl) species as the base peak in the ESI (negative) mass spectra further confirmed the strong binding of the halide ions in the gaseous phase.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons, Inc. |
ID Code: | 102522 |
Deposited On: | 23 Jan 2017 10:05 |
Last Modified: | 23 Jan 2017 10:05 |
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