VECTORIAL PET IN LB BILAYERS AND IN VESICLES - NANOSECOND FLUORESCENCE AND LASER FLASH-PHOTOLYSIS INVESTIGATION

Vectorial photoinduced electron transfer was investigated in Langmuir- Blodgett bilayers and in vesicles with the same phospholipid compositi on. The donor was covalently bound to one of the hydrophobic chains of the phospholipid in the mimetic membrane, whereas the acceptor was ad sorbed at the polar head group surface. The location of the redox coup le was preliminarily determined studying the photophysical properties of the donor in the phospholipid bilayer as well as the process of ads orption of the acceptor at the phospholipid-water interface. The photo induced electron transfer reaction was studied measuring the quenching of pyrene fluorescence in the presence of increasing concentrations o f acceptor, the process was studied both with steady-state and time-re solved fluorescence emission in the nanosecond time scale. The reactio n transient species formed upon photoexcitation were identified perfor ming nanosecond laser-flash photolysis experiments in vesicle systems. The dynamics of the charge recombination process following photoinduc ed electron transfer, was investigated studying the kinetic of decay o f the absorption signal of the transient species.