Influence of multicharged inorganic and organic cations on J-aggregation of polymethine dyes

Abstract

It is shown that the investigated inorganic and organic cations promote a shift in the equilibrium of the dimer ↔ J-aggregate of anionic thiatrimethine cyanine dyes toward J-aggregates. In this case, the ion concentration, which causes the equilibrium shift, depends substantially on the charge of the cation and exponentially decreases with an increase in the charge. It is concluded that the formation of more thermody-namically stable compounds, which include the aggregates of dyes and multicharged cations, contributes to the stabilization of the J-aggregates of dyes. It is show n for the first time that the multicharged cations stabilize both spatial isomers of J-aggregates of meso-ethylthiatrimethine cyanines: J cis and J trans-aggregates.