Excitation energy transfer between J-aggregates of cyanine dyes in Langmuir-Blodgett films and liposomes

Abstract

LB films and liposomes incorporating J-aggregates of two kinds of cyanine dyes at the same membrane surface have been prepared. Four cyanine dyes, 1,1′-diethyl-2,2′-cyanine chloride or iodide (dye-I), 5,6,5′,6′-dibenzo-1,1′-diethyl-2,2′-cyanine chloride (dye-II), 5,5′-dichloro-3,3′-diethyl-9-phenylthiacarbocyanine chloride (dye-III), 3,3′-dimethyl-9-phenyl-4,5,4′,5′-naphthothiacarbocyanine chloride (dye-IV) were employed. In the case of a couple of dye- II: dye- III aggregates, quenching of resonance fluorescence of dye-II aggregate and sensitization of resonance fluorescence of dye-III aggregate, due to excitation energy transfer, were observed. The energy transfer also occurs in the dye- I: dye- III, dye- I: dye- IV, dye- II: dye- IV aggregates. In these cases, quinocyanine dye (dye-I, dye-II) aggregates and thiacarbocyanine dye (dye-III, dye-IV) aggregates act as the energy donor and acceptor, respectively.