Study of lateral electron transfer in Langmuir–Blodgett films containing cyanine and viologen amphiphiles

The efficiency of the lateral photo-induced electron transfer between cyanine (electron donor) and viologen (electron acceptor) amphiphiles (Cy and V, respectively) was examined by observing the absorption and emission spectra of V doped Cy LB films. The sharp J-band observed in the absorption and fluorescence spectra indicated the efficient formation of J-aggregate of the cyanine chromophore even in the mixed LB monolayers with V. The fluorescence intensities of the J-band decreased monotonously with the increase of V concentration but the dependence of the electron transfer efficiency on the film composition was rather complicated. The efficiency of the lateral electron transfer estimated at the composition region of the lower V ratios, where V molecules are expected to disperse homogeneously into the Cy monolayer, was such that ca. 90 molecules of Cy would be quenched by one center molecule of V.