ADSORPTION AND AGGREGATION OF A CATIONIC CYANINE DYE ON SMECTITES

The adsorption and aggregate formation of a cationic cyanine dye, 1,1' -diethyl-2,2'-cyanine, on montmorillonite and saponite have been inves tigated for aqueous suspensions and cast films. In aqueous suspensions , the cyanine dye cations formed J-aggregates on montmorillonite, whil e they distribute molecularly on saponite. On the other hand, the dye formed J-aggregates on both montmorillonite and saponite in the cast f ilms. Thus, the spectroscopic features of the cyanine dye reflected th e difference between montmorillonite and saponite in organizing guest species, This difference suggests that the cyanine dye can be organize d in a controlled manner by the selection of host materials. The J-agg regates formed on the layered silicates may be useful for the study of optical properties of the aggregates because of their stable and conf ined microstructure.