Mahmood, Zafar and Sukhanov, Andrey A. and Rehmat, Noreen and Hu, Mengyu and Elmali, Ayhan and Xiao, Yi and Zhao, Jianzhang and Karatay, Ahmet and Dick, Bernhard and Voronkova, Violeta K. (2021) Intersystem Crossing and Triplet-State Property of Anthryl- and Carbazole-[1,12]fused Perylenebisimide Derivatives with a Twisted pi-Conjugation Framework. JOURNAL OF PHYSICAL CHEMISTRY B, 125 (32). pp. 9317-9332. ISSN 1520-6106, 1520-5207
Full text not available from this repository. (Request a copy)Abstract
Heavy atom-free triplet photosensitizers (PSs) are particularly of interest concerning both fundamental photo-chemistry study and practical applications. However, achieving efficient intersystem crossing (ISC) in planar heavy atom-free aromatic organic compounds is challenging. Herein, we demonstrate that two perylenebisimide (PBI) derivatives with anthryl and carbazole moieties fused at the bay position, showing twisted pi-conjugation frameworks and red-shifted UV-vis absorption as compared to the native PBI chromophore (by 75-1610 cm(-1)), possess efficient ISC (singlet oxygen quantum yield: Phi(Delta) = 85%) and a long-lived triplet excited state (tau(T) = 382 mu s in fluid solution and tau(T) = 4.28 ms in solid polymer film). Femtosecond transient absorption revealed ultrafast intramolecular charge-transfer (ICT) process in the twisted PBI derivatives (0.9 ps), and the ISC takes 3.7 ns. Pulsed laser excited time-resolved electron paramagnetic resonance (TREPR) spectra indicate that the triplet-state wave function of the twisted PBIs is mainly confined on the PBI core, demonstrated by the zero-field-splitting D parameter. Accordingly, the twisted derivatives have higher T-1 energy (E-T1 = 1.48-1.56 eV) as compared to the native PBI chromophore (1.20 eV), which is an advantage for the application of the derivatives as triplet PSs. Theoretical computation of the Franck-Condon density of states, based on excited-state dynamics methods, shows that the efficient ISC in the twisted PBI derivatives is due to the increased spin-orbit coupling matrix elements for the S-1-T-1 and S-1-T-2 states [spin-orbit coupling matrix element (SOCME): 0.11-0.44 cm(-1). SOCME is zero for native PBI], as well as the Herzberg-Teller vibronic coupling. For the planar benzoPBI, the moderate ISC is due to S-1 -> T-2 transition (SOCME: 0.03 cm(-1). The two states share a similar energy, ca. 2.5 eV).
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CYCLOMETALATED IR(III) COMPLEXES; INTRAMOLECULAR CHARGE-TRANSFER; EXCITED-STATE; ELECTRON-TRANSFER; DI(PERYLENE BISIMIDE)S; HIGHLY EFFICIENT; ENERGY-TRANSFER; RADICAL-ANIONS; PHOTOSENSITIZERS; SINGLET; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Bernhard Dick |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 13 Sep 2022 07:17 |
| Last Modified: | 13 Sep 2022 07:17 |
| URI: | https://pred.uni-regensburg.de/id/eprint/47271 |
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