Effect of chain length on stoichiometry of complex formation between α,ω-diphenylpolyenes and N,N-dimethylaniline in excited state

In order to study the effect of size on the stoichiometry of complexes formed as intermediates in photoinduced electron transfer (PET) reaction we considered electron transfer between three α,ω-diphenylpolyenes; all-s-trans-1,4-diphenylbuta-1,3-diene (DPB), all-s-trans-1,6-diphenylhexa-1,3,5-triene (DPH) and all-s-trans-1,8-diphenylocta-1,3,5,7-tetraene (DPO) and N,N-dimethylaniline (DMA). Two types of complexes, exciplex and triplex, were identified with the help of an external magnetic field. These results were further supported by steady-state fluorescence study, where the spectra showed existence of both complexes depending on concentration of DMA and chain length of the polyenes.