SPECTROSCOPIC STUDIES OF SUPRAMOLECULE FORMATION THROUGH CATION-INDUCED AGGREGATION OF PHTHALOCYANINE WITH 4 CROWN-ETHER VOIDS

The alkali cation complexation of phthalocyanine substituted with four crown ether rings (H(2)CRPc) was studied by UV-visible absorption and fluorescence spectroscopy. Cation-induced aggregation of the crowned phthalocyanine occurred in solution. When the diameters of the cations (K+, Rb+) slightly exceeded that of the crown ether ring, they acted cooperatively leading to the formation of a cofacial dimer. Smaller ca tions (Li+, Na+), which could be encapsulated into the cavity of the c rown ether voids, were unable to cause complete conversion to a cofaci al dimer. Large Cs+ ions induced sandwich-like aggregation in solution more rapidly. The monomer-dimer equilibrium formation constants for K +-and Rb+-induced aggregation were calculated to be of the order of 10 (9) l(2) M(-2).