Studies of energy/electron transfer in the photoluminescence process of bipolar Al-complex containing phenothiazine group

The photophysical properties of three bipolar complexes, Al(PHQ)3 (1), AlQ(PHQ)2 (2), and AlQ2(PHQ) (3) (Q = 8-hydroxyquinoline, PHQ = 5-[(phenothiazine-9′-yl)methyl]-8-hydroxyquinoline) were studied by UV–vis absorption and fluorescent spectra. The results showed that both energy transfer and electron transfer from phenothiazine (Ptz) group to Alq3-center had taken place in the photoluminescence (PL) process of the bipolar Al-complex. Förster non-radiative energy transfer theory together with fluorescent spectra were applied to investigate the energy transfer process of these bipolar Al-complexes. Additionally, thermodynamic analysis validated the possibility of the photo-induce electron transfer (PET) process. To further confirm the PET process, Cu2+ ion was used to oxidize aromatic amine of phenothiazine group to observe the variation of both the absorption and emission spectra of Al(PHQ)3. Moreover, dynamics of the PET process were also studied by dynamic fluorescence, and some dynamic constants were obtained.

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► Bipolar Al-complexes containing Alq3-center and phenothiazine group.
► Photophysical properties of the complexes were studied.
► Both energy transfer and electron transfer take place in the PL of the complexes.
► Thermodynamics and dynamics of electron transfer were studied.