Ternary AOT/water/hexane systems as “micellar sieves” for cyanine dye J-aggregates

We investigate the behavior of J-aggregates of a cyanine dye, 3,3′3,3′-di-(γ  -sulfopropyl)-4,5,4′,5′4,5,4′,5′-dibenzo-9-ethylthiacarbocyanine betaine pyridinium salt, in AOT/water/hexane reverse micelles (W=2–50W=2–50), both during the course of rapid microemulsion formation and then after stabilization of the microemulsions at thermodynamic equilibrium. We suggest a new mechanism for J-aggregate formation in reverse micelle solutions. According to this model J-aggregates are formed in the aqueous phase prior to formation of a stable microemulsion, rather than in the process of intermicellar exchange. Reverse micelles encapsulate only those J-aggregates whose size is smaller than the mean size of the water pool. Larger J-aggregates located in hexane gradually precipitate from solution. It is demonstrated that micellar solutions can be used as “sieves” for selection and stabilization of J-aggregates with a desired size.

Graphical abstractReverse micelle solutions can be used as “sieves” for selection and stabilization of J-aggregates with a desired size: micelles encapsulate J-aggregates whose size is smaller than the water pool size.Figure optionsDownload full-size imageDownload as PowerPoint slide