Wang, Zhijia and Toffoletti, Antonio and Hou, Yuqi and Zhao, Jianzhang and Barbon, Antonio and Dick, Bernhard (2021) Insight into the drastically different triplet lifetimes of BODIPY obtained by optical/magnetic spectroscopy and theoretical computations. CHEMICAL SCIENCE, 12 (8). pp. 2829-2840. ISSN 2041-6520, 2041-6539
Full text not available from this repository. (Request a copy)Abstract
The triplet state lifetimes of organic chromophores are crucial for fundamental photochemistry studies as well as applications as photosensitizers in photocatalysis, photovoltaics, photodynamic therapy and photon upconversion. It is noteworthy that the triplet state lifetime of a chromophore can vary significantly for its analogues, while the exact reason was rarely studied. Herein with a few exemplars of typical BODIPY derivatives, which show triplet lifetimes varying up to 110-fold (1.4-160 mu s), we found that for these derivatives with short triplet state lifetimes (ca. 1-3 mu s), the electron spin polarization (ESP) pattern of the time-resolved electron paramagnetic resonance (TREPR) spectra of the triplet state is inverted at a longer delay time after laser pulse excitation, as a consequence of a strong anisotropy in the decay rates of the zero-field state sublevel of the triplet state. For the derivatives showing longer triplet state lifetimes (>50 mu s), no such ESP inversion was observed. The observed fast decay of one sublevel is responsible for the short triplet state lifetime; theoretical computations indicate that it is due to a strong coupling between the T-z sublevel and the ground state mediated by the spin-orbit interaction. Another finding is that the heavy atom effect on the shortening of the triplet state lifetime is more significant for the T-1 states with lower energy. To the best of our knowledge, this is the first systematic study to rationalize the short triplet state lifetime of visible-light-harvesting organic chromophores. Our results are useful for fundamental photochemistry and the design of photosensitizers showing long-lived triplet states.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TIME-RESOLVED EPR; INTRAMOLECULAR CHARGE-TRANSFER; ELECTRON-PARAMAGNETIC-RES; EXCITED-STATES; UP-CONVERSION; FLUORESCENCE; ABSORPTION; TRANSIENT; DYNAMICS; PHOTOSENSITIZERS; |
| 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 08:15 |
| Last Modified: | 13 Sep 2022 08:15 |
| URI: | https://pred.uni-regensburg.de/id/eprint/47275 |
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