Panchromatic Light‐Capturing Bis‐styryl BODIPY‐Perylenediimide Donor‐Acceptor Constructs: Occurrence of Sequential Energy Transfer Followed by Electron Transfer

Abstract

Two wide‐band capturing donor‐acceptor conjugates featuring bisstrylBODIPY and perylenediimide (PDI) have been newly synthesized and the occurrence of ultrafast excitation transfer from the 1PDI* to BODIPY, and a subsequent electron transfer from the 1BODIPY* to PDI has been demonstrated. Steady‐state fluorescence and excitation spectral recordings provided evidence of singlet‐singlet energy transfer in these dyads, and quenched fluorescence of bisstyrylBODIPY emission in the dyads suggested additional photo‐events. The electrostatic potential surfaces of the S1 and S2 states, derived from time‐dependent DFT calculations, supported excited charge transfer in these dyads. Spectroelectrochemical studies on one‐electron oxidized and one‐electron reduced dyads and the monomeric precursor compounds were also performed in a thin‐layer optical cell under corresponding applied potentials. From this study, both bisstrylBODIPY.+ and PDI.‐ were possible to spectrally characterize and were subsequently utilized in characterizing the electron transfer products. Finally, pump‐probe spectral studies were performed in dichlorobenzene under selective PDI and bisstyrylBODIPY excitation to secure energy and electron transfer evidence. The measured rate constants for energy transfer, kENT were in the range of 1011 s‐1 while the electron transfer rate constants, kET were in the range of 1010 s‐1 highlighting their potential use in solar energy harvesting and optoelectronic applications.

Excited Charge Separation in a π-Interacting Phenothiazine–Zinc Porphyrin–Fullerene Donor–Acceptor Conjugate

“…This computational study confirms the occurrence of charge transfer involving both the S 1 and S 2 states in SPS-PPY-C 60 , with the phenothiazine-porphyrin unit acting as an electron donor and fullerene as an electron acceptor. 47 This observation correlates well with the earlier discussed absorption spectral results, wherein charge transfer type interactions were observed for both the soret and visible bands of the triad.…”

Symmetry breaking charge transfer leading to charge separation in a far-red absorbing bisstyryl-BODIPY dimer

“…In the molecular design, two phenyl-styryl entities on each BODIPY are appended to shift the absorption and emission to the 650 nm range. 43–46 As summarized below, efficient SBCS is indeed observed in the dimer in polar solvents with appreciable lifetimes of the charge-separated species.…”