Complexation Thermodynamics of p-tert-Butylcalix[4]arene Derivatives with Light Lanthanoid Nitrates in Acetonitrile

Yu Liu, Shang Li, Xiao Peng Bai, Takehiko Wada, Yoshihisa Inoue

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Calorimetric titrations have been performed for the first time in anhydrous acetonitrile at 25°C to give the complex stability constant (KS) and thermodynamic quantities for the complexation of light lanthanoid(III) nitrates (La-Gd) with 5,11,17,23-tetra-tert-butyl-26,28-bis(cyanomethoxy)-25,27-dihydroxycalix[4]arene (1) and 5,11,1723-tetra-tert-butyl-26, 28-bis(2-aminoethoxy)-25,27-dihydroxycalix[4]arene (2). X-ray crystallographic structures of 1 and 2 were also determined and compared. Possessing the cyanomethoxy and aminoethyl substituants, 1 and 2 displayed strikingly different cation binding abilities and selectivity profiles with much higher KS values for La3+ and Ce3+, which may be related to the original structures in the solid state. Thus, the binding profile for 2 showed a rapid decrease in KS with decreasing ionic diameter from La3+ to Pr3+ and then became flat up to Gd3+, while 1 gave a very flat profile which is superimposable with that for 2 between Pr3+-Gd3+. Thermodynamically, the complexation is driven absolutely by enthalpy which compensates the entropic loss arising from the structural freezing of the calix[4]arene derivatives upon simultaneous binding of lanthanoid ion by the phenolic oxygen and acetonitrile molecule in the cavity. The general validity and the meaning of the compensative enthalpy-entropy relationship observed are discussed.

Original languageEnglish
Pages (from-to)529-537
Number of pages9
JournalSupramolecular Chemistry
Volume13
Issue number4
DOIs
Publication statusPublished - 2001 Jan 1
Externally publishedYes

Keywords

  • Calix[4]arene derivatives
  • Calorimetric titration
  • Complexation thermodynamics
  • Ions selectivities
  • Light lanthanoid cations

ASJC Scopus subject areas

  • Chemistry(all)

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