Abstract: The induced formation of J-aggregates of ionic cyanines by the J-aggregates of ionic cyanines with opposite charges was studied by vis-absorption spectra in aqueous solutions at room temperature. It was found that the induction effect was more pronounced by dye aggregates than by polyelectrolytes. It was also found that the addition of a polyelectrolyte or an inorganic salt together with the aggregation inducing J-aggregates would reduce the induction effect of the latter owing to the partial depression of its charge. Efficiently inducing action was favored when the two cyanines have closely related structure to facilitate the formation of compatible segregated J-stacks of the two ionic dyes. Amodel with the structural compatible totality of segregated J-stacks for the two oppositely charged ionic cyanine dyes was proposed from the results.

Key words: Absorption spectra, Cyanine dyes, J-aggregate