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The association constants of Na+with dibenzo[3n]crown-nin THF/water using ISE

Authors
Journal
Talanta
0039-9140
Publisher
Elsevier
Publication Date
Volume
64
Issue
4
Identifiers
DOI: 10.1016/j.talanta.2004.03.058
Keywords
  • Potentiometry
  • Ion Selective Electrodes
  • Macrocyclic Ethers
  • Na+Ion Complexes

Abstract

Abstract The Na + association constants, K 11 and β 12, of 1/1 and 1/2 stoichiometry of macrocycles of (1,2)dibenzo[15]crown-5, (1,3)dibenzo[18]crown-6, (1,4)dibenzo[21]crown-7, (2,3)dibenzo[21]crown-7, (2,4)dibenzo[24]-crown-8 and dicyclohexano[24]crown-8 were determined in THF/water, (50/50), mixtures. We used a Methrom Na + ISE for the potentiometric measurements and applied the 1/( β nm [A o +]) n+ m−1 =(1− nP c)(1− mP c)/ P c equation where the P c= P/[1+( m−1) P] and P is the mole fraction of the complexed cation, [A n +L m ] for association constants with linear best fit. Results were in well agreement with the macrocyclic size and cation radii relationships. Measurements showed the role of aromatic groups of macrocyclics in THF/water (50/50) which allowed the macrocyclic molecules more selectively bind Na + compared to the associations those obtained in water.

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