Fluorescence Quenching of 4,4′-Dimethoxytriphenylamine-Substituted Diketopyrrolopyrrole via Intramolecular Photoinduced Electron Transfer

Herein, we report significant fluorescence quenching induced by intramolecular photoinduced electron transfer (PET) in electron donor-acceptor-type π-conjugated organic molecules with methoxy-containing donor moieties. The fluorescence quenching of the diketopyrrolopyrrole (DPP, a well-known highly emissive luminophore) derivatives seemed to be affected by the methoxy moieties. Steady-state optical properties of the synthesized materials were analyzed in the solution, aggregate (N-methyl-2-pyrrolidone/H₂O), and solid states in order to understand the influence of the surrounding environment. The mechanistic aspect of the intramolecular PET process in methoxy-containing DPP derivatives was revealed by singlet oxygen generation measurements and ultrafast femtosecond transient absorption spectroscopy. These results could provide crucial insights toward designing emissive π-conjugated organic molecules.