Journal of the American Chemical Society, Vol.118, No.7, 1762-1768, 1996
Solvent and Distance-Dependent Charge Separation in Rigid Trichromophoric Systems
Transient absorption and time-resolved microwave studies have been carried out on a series of D(onor)(2)-[bridge]-D(onor)(1)-[bridge]-A(cceptor) compounds, in which a dimethoxynaphthalene (DMN) primary donor (D-1) and a dicyanovinyl (DCV) acceptor are separated by a rigid norbornylogous bridge eight sigma-bonds in length and an N,N-dimethylaniline secondary donor (D-2) is separated from D-1 by a norbornylogous bridge of variable length (four, six, or eight sigma-bonds). The identity of the charge-separated state populated upon photoexcitation, i.e., from D-1 to A or from D-2 to A, depends on the solvent polarity and the length of the bridge separating both donor chromophores. It was found that the final charge-separated state is formed on a (sub)nanosecond time scale, whereas charge recombination shows strong solvent dependence, due to "inverted region" behavior.
Keywords:PHOTOINDUCED ELECTRON-TRANSFER;PHOTOSYNTHETIC REACTION-CENTER;ACCEPTOR COMPLEXES;ZINC PORPHYRIN;QUINONE TRIADS;DONOR;RECOMBINATION;DYNAMICS;ENERGY;DYADS