Molecular recognition of amphiphilic p-sulfonatocalix[4]arene with organic ammoniums
The binding abilities and thermodynamic origin for the intermolecular complexation of two water-soluble calixarenes, p
-sulfonatocalix[4]arene (SC4A) and 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(n
-butyl)-calix[4]arene (SC4A-Bu),
with six organic cations: 1,4-diazabicyclo[2,2,2]octane (G1), 3,5,6,8,-tetrahydropyrazino[1,2,3,4-Imn][1,10]phenanthroline (G2), diquat (G3), paraquat (G4), 1-methylpyridin-1-ium (G5) and 1,3-dimethylimidazolium (G6), have been determined by means of isothermal
titration calorimetry in aqueous solutions at pH 7.0, 298.15 K, and their binding modes have been investigated by NMR spectroscopy. The obtained results indicate that the binding modes of SC4A-Bu and SC4A change a little but their binding affinities show great difference, resulting from
the distinguishable binding thermodynamics. The binding selectivity of G1 is up to 688 times for the SC4A/SC4A-Bu hosts, and SC4A-Bu prefers to include planer molecules of large π system with low electron density. The aggregation behaviours of SC4A-Bu before and after complexation
with G3 were then investigated, showing that G3 is able to induce the aggregation of SC4A-Bu.
Keywords: ammonium; amphiphile; calixarene; recognition; thermodynamics
Document Type: Research Article
Affiliations: State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300071, P.R. China
Publication date: 03 June 2015
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