Spectroscopic and structural studies of cyanine dyes in functionalized Langmuir-Blodgett films: Electron and energy transfer processes

Formation of the J-aggregates with redshifted bands and the H-aggregates with blue-shifted bands for a long-chain merocyanine (MC) could be controlled by mixing the molecular matrix components in the monolayer assembly. The binary Langmuir-Blodgett (LB) film containing MC and Cd arachidate (AA) provided the J-aggregates which have a sharp fluorescence with less Stokes shift. The ternary LB system having MC-AA and octadecane (OD) showed the H-aggregates in addition to the J-aggregates. The structures of the J- and H-aggregates were studied by atomic force microscopy and X-ray diffraction analysis. Additionally, the photo-induced electron transfer from the MC J-aggregate donor to a long-chain bipyridilium and the energy transfer from another cyanine dye donor to the MC H-aggregate acceptor were investigated in the hetero-LB films by varying the separation between the donor and acceptor layers.