The accumulation of photochromic energy acceptor species in A–S dyad Langmuir–Blodgett films

Fluorescence and absorption spectra were measured on Langmuir–Blodgett (LB) films containing acceptor–sensitizer (A–S) dyads. In the dyads, the length of hydrocarbon bridges interconnecting acceptor (viologen) and sensitizer (pyrene) were synthetically changed. In the LB films, the accumulation of viologen cation radical which can quench the excited pyrene moiety as an energy acceptor was observed during UV irradiation under N 2 . The rate constant of photoinduced intramolecular electron transfer in the LB films was estimated from the fluorescence intensities by taking the energy transfer quenching into consideration.