Bergwinkl, Sebastian and Nuernberger, Patrick and Dick, Bernhard and Kutta, Roger Jan (2024) Enhanced Intersystem Crossing in a Thiohelicene. CHEMPHOTOCHEM, 8 (7). ISSN 2367-0932,
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The photophysics of a helicene derivative in which two benzene units are replaced by thiophene units (thiohelicene, 6H) was studied by steady state and transient absorption and emission spectroscopies covering time ranges from femtoseconds to minutes. Efficient intersystem crossing (ISC) to the triplet state was observed, by far exceeding that of the parent helicene and the corresponding oxo-helicene. Quantum chemical calculations indicate that the helical distortion and the heavy atom effect of sulfur cooperate in promoting spin-orbit coupling, and that the most efficient decay channel involved the T2 or even the T3 state. These insights can help in the design of more efficient triplet sensitizers for many applications. Photolabile 6-Iodo-thiohelicene forms thiohelicene. In both molecules, cooperative helical distortion and internal heavy-atom effect lead to efficient triplet formation with a rather long lifetime for thiohelicene emitting detectable phosphorescence at room temperature in degassed solution. The biradical triplet decays in a bimolecular reaction at high triplet concentration putatively resulting in a ring closure mediated by an excited state complex. image
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ONE HUNDRED YEARS; STEREOSELECTIVE SYNTHESES; CIRCULAR-DICHROISM; ABSORPTION; IDENTIFICATION; DERIVATIVES; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) 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: | 28 Jul 2025 09:12 |
| Last Modified: | 28 Jul 2025 09:12 |
| URI: | https://pred.uni-regensburg.de/id/eprint/63843 |
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