کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
673964 | 1459536 | 2012 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Host–guest interactions between 4-sulfonatocalix[8]arene and 1-alkyl-3-methylimidazolium type ionic liquids Host–guest interactions between 4-sulfonatocalix[8]arene and 1-alkyl-3-methylimidazolium type ionic liquids](/preview/png/673964.png)
The inclusion of 1-alkyl-3-methylimidazolium ions (Cnmim+) in 4-sulfonatocalix[8]arene was studied by isothermal titration calorimetry in aqueous solution at 298 K. Sequential formation of 1:1 and 2:1 complexes occurred in enthalpy driven reactions. The alteration of the molecular structure of the guest barely affected the driving force of the confinement of the first Cnmim+. However, the binding affinity of the second Cnmim+ went through a maximum when the number of carbon atoms in the side chain was increased. The enthalpy and entropy change diminished linearly with the length of the aliphatic substituent of Cnmim+ for 1:1 complexation, but reached a minimum for the hexyl homologue in the case of 2:1 inclusion. Linear entropy–enthalpy correlations were found with smaller slope and intercept for the second binding step.
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► 1-Alkyl-3-methylimidazolium forms 1:1 and 2:1 complexes with sulfonatocalix[8]arene.
► Length of the alkyl group of the guest barely affects the stability of 1:1 complex.
► ΔG of 2:1 association goes through a minimum in the series of the guests.
► ΔH and ΔS of 1:1 binding show parallel decrease as the alkyl group of is lengthened.
► ΔH and ΔS of 2:1 inclusion reach minimum in the homologous series of guests.
Journal: Thermochimica Acta - Volume 548, 20 November 2012, Pages 76–80