Spin–Orbit Charge‐Transfer Intersystem Crossing in Anthracene–Perylenebisimide Compact Electron Donor–Acceptor Dyads and Triads and Photochemical Dianion Formation

Rehmat, Noreen; Kurganskii, Ivan V.; Mahmood, Zafar; Guan, Qing Lin; Zhao, Jianzhang; Xing, Yong Heng; Gurzadyan, Gagik G.; Fedin, Matvey V.

doi:10.1002/chem.202005285

Cited by 20 publications

(39 citation statements)

References 114 publications

(197 reference statements)

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“…However, our recent studies show that the ESP is not strictly ISC mechanism-specific, that is, the triplet state formed via SOCT-ISC may show the same ESP as that formed by SO-ISC . We also found that the ESP of the triplet-state TREPR spectrum of a chromophore in the electron donor–acceptor dyads is not only dependent on the mutual orientation of the donor and acceptor, as proposed previously, it is also dependent on the structure of the electron donor (or acceptor) and even the number of the electron donors attached on the electron acceptor …”

Section: Resultssupporting

confidence: 76%

Charge Transfer, Intersystem Crossing, and Electron Spin Dynamics in a Compact Perylenemonoimide-Phenoxazine Electron Donor–Acceptor Dyad

et al. 2021

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With phenoxazine (PXZ) as the electron donor and perylene-3,4-dicarboximide (PMI) as the electron acceptor, we prepared a compact, orthogonal electron donor−acceptor dyad (PMI−PXZ) to study the spin−orbit charge transfer-induced intersystem crossing (SOCT-ISC). A weak charge transfer (CT) absorption band, due to S 0 → 1 CT transition, was observed (ε = 2840 M −1 cm −1 at 554 nm, FWHM: 2850 cm −1 ), which is different from that of the previously reported analogue dyad with phenothiazine as the electron donor (PMI−PTZ), for which no CT absorption band was observed. A long-lived triplet state was observed (lifetime τ T = 182 μs) with nanosecond transient absorption spectroscopy, and the singlet oxygen quantum yield (Φ Δ = 76%) is higher than that of the previously reported analogue dyad PMI−PTZ (Φ Δ = 57%). Ultrafast charge separation (ca. 0.14 ps) and slow charge recombination (1.4 ns) were observed with femtosecond transient absorption spectroscopy. With time-resolved electron paramagnetic resonance spectroscopy (TREPR), we confirmed the SOCT-ISC mechanism, and the electron spin polarization phase pattern of the triplet-state TREPR spectrum is (e, e, a, e, a, a), which is dramatically different from that of PMI−PTZ (a, e, a, e, a, e), indicating that the triplet-state TREPR spectrum of a specific chromophore in the electron donor−acceptor dyads is not only dependent on the geometry of the dyads but also dependent on the structure of the electron donor (or acceptor). Even one-atom variation in the donor structure may cause significant influence on the electron spin selectivity of the ISC of the electron donor−acceptor dyads.

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Section: Resultssupporting

confidence: 76%

Charge Transfer, Intersystem Crossing, and Electron Spin Dynamics in a Compact Perylenemonoimide-Phenoxazine Electron Donor–Acceptor Dyad

et al. 2021

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“…Although ISC was observed indirectly for the donor‐PDI dyads through 1 O 2 generation (Table 3), DFT optimized geometries indicated the absence of a perfect donor‐acceptor orthogonality (Table 1), often described as an essential feature in the SOCT‐ISC process [18] . However, recently reported PDI dyads showed the same deviation of the perpendicular donor‐acceptor orientation, while maintaining efficient SOCT‐ISC [9t,w] . To look deeper into the possible pathways for ISC, the quantum‐chemical and photophysical analyses were combined.…”

Section: Resultsmentioning

confidence: 99%

“…Barbon and coworkers developed carbazole‐PDI dyads with the carbazole donor attached to one of the two imide positions, [9t] while Fedin et al . chose to functionalize a bay‐position with a weakly donating anthracene moiety [9w] …”

Section: Introductionmentioning

confidence: 99%

Heavy‐Atom‐Free Bay‐Substituted Perylene Diimide Donor‐Acceptor Photosensitizers

et al. 2021

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Perylene diimide (PDI) dyes are extensively investigated because of their favorable photophysical characteristics for a wide range of organic material applications. Fine-tuning of the optoelectronic properties is readily achieved by functionalization of the electron-deficient PDI scaffold. Here, we present four new donor-acceptor type dyads, wherein the electron donor units -benzo[1,2-b : 4,5-b']dithiophene, 9,9-dimethyl-9,10-dihydroacridine, dithieno[3,2-b : 2',3'-d]pyrrole, and triphenylamineare attached to the bay-positions of the PDI acceptor. Intersystem crossing occurs for these systems upon photo-excitation, without the aid of heavy atoms, resulting in singlet oxygen quantum yields up to 80 % in toluene solution. Furthermore, this feature is retained when the system is directly irradiated with energy corresponding to the intramolecular charge-transfer absorption band (at 639 nm). Geometrical optimization and (time-dependent) density functional theory calculations afford more insights into the requirements for intersystem crossing such as spin-orbit coupling, dihedral angles, the involvement of charge-transfer states, and energy level alignment.

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“…In addition, in the calculation of the vertical excitation energies, several effects that can significantly change the positions of the band maxima in the experimental spectrum were ignored. In particular, these calculations neglect the effects of vibrations (e.g., vibronic coupling and Jahn-Teller distortions) [45], spin-orbit coupling [46], and the environment [47], in cases where the spectra have been measured in solution or in a condensed medium. Hence, without including these additional effects in our calculations, there may be considerable discrepancies between the computed excitation energies and experimental band maxima, even with higher levels of theory and large basis sets.…”

Section: Atz Singlet Electronic Statesmentioning

confidence: 99%

Photochemistry of 1-Phenyl-4-Allyl-Tetrazol-5-One: A Theoretical Study Contribution towards Mechanism Elucidation

2021

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The photodegradation mechanism of 1-phenyl-4-allyl-tetrazol-5-one has been studied using (time-dependent) density functional theory with the M06-HF, B3LYP, and PBE0 functionals and the VDZ basis set. All calculations have been carried out using the polarizable continuum model to simulate the solvent effects of methanol. The reaction pathway evolution on the triplet state has been characterised to validate a previously postulated experimental-based mechanism. The transition states and minimums have been initially located by local scanning in partial constrained optimisation, followed by a fully relaxed search procedure. The UV spectra has shown to be better described with PBE0 functional when compared with the experimental results, having the M06-HF a shift of 40 nm. From the energetic point of view, the postulated mechanism has been validated in this work showing a concerted photoextrusion of the N2 molecule. The intramolecular proton transfer occurs at a later stage of the mechanism after cyclization of the allyl group on a triplet biradical intermediate. The photoproduct observed experimentally, a pyrimidinone, has been characterised. The infrared spectroscopic reaction profile has also been proposed.

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Spin–Orbit Charge‐Transfer Intersystem Crossing in Anthracene–Perylenebisimide Compact Electron Donor–Acceptor Dyads and Triads and Photochemical Dianion Formation

Cited by 20 publications

References 114 publications

Charge Transfer, Intersystem Crossing, and Electron Spin Dynamics in a Compact Perylenemonoimide-Phenoxazine Electron Donor–Acceptor Dyad

Charge Transfer, Intersystem Crossing, and Electron Spin Dynamics in a Compact Perylenemonoimide-Phenoxazine Electron Donor–Acceptor Dyad

Heavy‐Atom‐Free Bay‐Substituted Perylene Diimide Donor‐Acceptor Photosensitizers

Photochemistry of 1-Phenyl-4-Allyl-Tetrazol-5-One: A Theoretical Study Contribution towards Mechanism Elucidation

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