T. Toupance et al., IONOELECTRONICS - CATION-INDUCED NONLINEAR COMPLEXATION - CROWN-ETHER-SUBSTITUTED AND POLY(ETHYLENE-OXIDE)-SUBSTITUTED LUTETIUM BISPHTHALOCYANINES, Journal of the American Chemical Society, 116(12), 1994, pp. 5352-5361
Lutetium bisphthalocyanines symmetrically substituted with crown ether
macrocycles ([(15-C-5)(4)Pc]Lu-2, [(18-C-6)(4)Pc]Lu-2) or linear poly
(ethylene oxide) chains ([(RO)(8)Pc]Lu-2) have been synthesized and ch
aracterized. An unsymmetrical complex ([(15-C-5)(4)Pc]Lu[Pc(OR)(8)]) i
s also described. The selectivity of complexation toward alkali cation
s is determined by the picrate extraction method. Titration curves hav
e been obtained by UV-visible spectroscopy, showing that large alkali
cations induce the formation of aggregates via a positive cooperativit
y effect. A sigmoidal titration curve is obtained for the couple [(18-
C-6)(4)Pc]Lu-2/Rb+. The shape of the curve is very similar to the one
obtained for the complexation of O-2 by hemoglobin, where a nonlinear
binding process is well established. The obtainment of this phenomenon
is a key step toward the realization of ionoelectronics networks.