Conformational control of electron tranafer states: Induction of molecular photodiode behaviour

Abstract

Fluorescence raie constants of various donor-acceptor biphenyl model compounds were compared with their corresponding absorption spectra in solvents of different polarity and analysed with respect to their molecular conformations in ground and excited states. For a pretwisted derivative, the typical behaviour of a molecular photodiode was observed Le, allowed access to the excited stale but forbidden return to the ground state. This is interpreted by assuming a structural relaxation towards an orbitally-decoupled conformation. Implications regarding similar observations for the photosynthetic reaction center are discussed. © VCH Verlagsgcsellschaft mbH,.