Broadband visible light harvesting BODIPY-perylene dyad and triad: Synthesis, photophysical properties, and photooxidation applications

In this study, diiodo boron dipyrromethene (BODIPY) is employed as the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride (PDA) as the energy acceptor, enabling the synthesis of two new compounds: a BODIPY-perylene dyad named Pl, and a triad named P2. To investigate the impact of the energy donor on the photophysical processes of the system, P1 comprises one diiodo-BODIPY unit and one PDA unit, whereas P2 contains two dhodo-BODIPY moieties and one PDA unit. Due to the good spectral complementarity between diiodo-BODIPY and PDA, these two compounds exhibit excellent light-harvesting capabilities in the 400–620 nm range. Steady-state fluorescence spectra demonstrate that when preferentially exciting the diiodo-BODIPY moiety, it can effectively transfer energy to PDA; when selectively exciting the PDA moiety, quenching of PDA fluorescence is observed in both P1 and P2. Nanosecond transient absorption results show that both compounds can efficiently generate triplet excited states, which are located on the PDA part. The lifetimes of the triplet states for these two compounds are 103 and 89 μs, respectively, significantly longer than that of diiodo-BODIPY. The results from the photooxidation experiments reveal that both P1 and P2 demonstrate good photostability and photooxidation capabilities, with P2 showing superior photooxidative efficiency. The photooxidation rate constant for P2 is 1.3 times that of P1, and its singlet oxygen quantum yield is 1.6 times that of P1. The results obtained here offer valuable insights for designing new photosensitizers.