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 characterized. An unsymmetrical complex ([(15-C-5)(4)Pc]Lu[Pc(OR)(8)]) is also described. The selectivity of complexation toward alkali cations is determined by the picrate extraction method. Titration curves have been obtained by UV-visible spectroscopy, showing that large alkali cations induce the formation of aggregates via a positive cooperativity 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.