Synthesis and cation-mediated electron transfer in intramolecular fluorescence quenching of donor-acceptor podands: observation of Marcus inverted region in forward electron transfer reactions

The synthesis of a series of donor-acceptor podands is described. The dependence of the rate constants of intramolecular photoinduced electron transfer on the exothermicity of the reaction was studied by stationary and time-resolved fluorescence spectroscopy. H-1 NMR and computational studies suggest that the conformational change of the podands is restricted by K+ binding. As a result, the occurrence of highly exothermic photoinduced electron transfer reaction within the Marcus inverted region was observed.