TY - JOUR
T1 - Ionizable (this)calix(4)crowns as highly selective 226RA2+ ionophores
AU - van Leeuwen, F.W.B.
AU - Beijleveld, H.
AU - Miermans, Cornelis J.H.
AU - Huskens, Jurriaan
AU - Verboom, Willem
AU - Reinhoudt, David
PY - 2005
Y1 - 2005
N2 - The 226Ra2+ selectivity of the ionizable (thia)calix[4]crowns 1-4 was determined in the presence of a large excess of the most common alkali and alkaline earth cations. Selective 226Ra2+ (2.9 × 10-8 M) extraction occurs even at extremely high Mn+/226Ra2+ ratios of 3.5 × 107 [Mn+ = Na+, K+, Rb+, Cs+, Mg2+, Ca2+, and Sr2+ (1 M)] and an ionophore concentration of 10-4 M. The selectivity coefficients log(KRaex/KMex) are ~3.5 for Mg2+, Ca2+, and Sr2+. In the presence of Ba2+, which has very similar chemical properties, only the thiacalix[4]crown-6 derivative 4 showed a selectivity for 226Ra2+. In addition to the remarkable 226Ra2+ selectivities, the effective pH range (pH 8-13) of the thiacalix[4]crown dicarboxylic acids (3 and 4) allows for full regeneration of the ionophores at lower pH values (pH <6).
AB - The 226Ra2+ selectivity of the ionizable (thia)calix[4]crowns 1-4 was determined in the presence of a large excess of the most common alkali and alkaline earth cations. Selective 226Ra2+ (2.9 × 10-8 M) extraction occurs even at extremely high Mn+/226Ra2+ ratios of 3.5 × 107 [Mn+ = Na+, K+, Rb+, Cs+, Mg2+, Ca2+, and Sr2+ (1 M)] and an ionophore concentration of 10-4 M. The selectivity coefficients log(KRaex/KMex) are ~3.5 for Mg2+, Ca2+, and Sr2+. In the presence of Ba2+, which has very similar chemical properties, only the thiacalix[4]crown-6 derivative 4 showed a selectivity for 226Ra2+. In addition to the remarkable 226Ra2+ selectivities, the effective pH range (pH 8-13) of the thiacalix[4]crown dicarboxylic acids (3 and 4) allows for full regeneration of the ionophores at lower pH values (pH <6).
U2 - 10.1021/ac050524n
DO - 10.1021/ac050524n
M3 - Article
VL - 77
SP - 4611
EP - 4617
JO - Analytical chemistry
JF - Analytical chemistry
SN - 0003-2700
IS - 14
ER -