Structuring of tricarbocyanine dye molecules in Langmuir-Blodgett films

The problems of formation of stable Langmuir monolayers containingN-sulfopropyl substituted thiatricarbocyanine dyes are considered: the effects of the composition of the mixture applied on the surface of an aqueous subphase and of the extent of compression of the monolayer on processes of ordering of molecular structure. Dyes are introduced into complex monolayers at the water-air interface and then are transferred on solid substrates as multilayered Langmuir-Blodgett (LB) films. For the first time the formation of J-aggregates has been observed for two tricarbocyanine dyes. The structure of J-aggregates depends on the composition of the mixture and the value of the constant pressure at which the transfer occurs. LB films of J-aggregated dyes are optically anisotropic, which is related to the fact that they are formed in the monolayer on the surface and there is no interlayer aggregation during the transfer to substrates. Heterodimers are formed in complex monolayers containing oppositely charged ions of dyes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1278–1283, July, 1995.The work was partially financially supported by the Foundation for Basic Research of the State Committee on Science and Technologies of the Ukraine (Project No. 2.2/48 Normal').