Excitation energy transfer from symmetric cyanine dyes to unsymmetric merocyanine aggregated in functionalized Langmuir–Blodgett films by time-resolved fluorescence spectroscopy

The fluorescence decays and ultrafast time-resolved spectra in mono- and multilayered Langmuir–Blodgett (LB) films were measured to explore the dynamics of excitation energy transfer between the monomer and aggregates of symmetric and unsymmetric cyanine dyes. J- and H-aggregate formation of a long-chain merocyanine dye depends upon the constituent of the molecular matrix. Steady-state and time-resolved spectroscopic studies of these dyes embedded in suitably designed monolayer assemblies revealed that a monomeric cyanine fluorescence is quenched by the aggregates of the merocyanine in the fatty acid–octadecane ternary system, indicating efficient energy transfer mechanism from the monomeric cyanine to the J-aggregates of merocyanine via the H-aggregates.