title: The association constants of Na(+) with dibenzo[3n]crown-n in THF/water using ISE.
abstract: The Na(+) association constants, K(11) and beta(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/(beta(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.
authors.affiliation: Department of Chemistry, Istanbul Technical University, Maslak, TR-34469, Istanbul, Turkey.
authors.forename: Gülcemal
authors.initials: G
authors.lastname: Yıdız
authors.forename: Gönül
authors.initials: G
authors.lastname: Yapar
authors.forename: Cakıl
authors.initials: C
authors.lastname: Erk