AGGREGATION AND PHOTOISOMERIZATION OF AMPHIPHILIC CROWN-ETHER STYRYL DYE IN MONOLAYERS AT THE INTERFACE

The molecules of trans-isomer of styryl dye la, containing the benzo-1 8-crown-6 moiety and the methoxybenzothiazole residue with the N-octad ecyl substituent, were shown to form stable, highly ordered monolayers at the water/air interface. Increasing the surface pressure of the mo nolayer results in the formation of the H-aggregated molecules of comp ound la. The H-aggregates tend to dissociate to the monomeric trans-fo rm, when the monolayer forms in the Langmuir-Blodgett film (LB film). The light irradiation of the LB films leads to the partially reversibl e trans-cis-photoisomerization of compound la, whose efficiency is muc h lower than that observed in an acetonitrile solution of In. The aggr egation of cis-la isomers in the LB film is suggested to hamper the re verse cis-trans-isomerization. The aggregation of trans-1a molecules i n the LB films does not occur in air, but, after dipping in an aqueous solution, molecules of the LB film slowly form J-aggregates. A model of the structural organization of trans-la molecules in the LB films w as proposed.