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- Title
Control of the Photo-Isomerization Mechanism in 3 H -Naphthopyrans to Prevent Formation of Unwanted Long-Lived Photoproducts.
- Authors
Brazevic, Sabina; Nizinski, Stanisław; Sliwa, Michel; Abe, Jiro; Rode, Michał F.; Burdzinski, Gotard
- Abstract
In the photochromic reactions of 3H-naphthopyrans, two colored isomers TC (transoid-cis) and TT (transoid-trans) are formed. In terms of optimized photo-switchable materials, synthetic efforts are nowadays evolving toward developing 3H-naphthopyran derivatives that would not be able to photoproduce the long-living transoid-trans, TT, photoproduct. The substitution with a methoxy group at position 10 results in significant reduction of the TT isomer formation yield. The TC photophysics responsible for TT suppression were revealed here using a combination of multi-scale time resolved absorption UV-vis spectroscopy and ab initio calculations. The substitution changes the TC excited-state potential energy landscape, the bicycle-pedal isomerization path is favored over the rotation around a single double bond. The bicycle-pedal path is aborted in halfway to TT formation due to S1→S0 internal conversion populating back the TC species in the ground electronic state. This is validated by a shorter TC S1 state lifetime for methoxy derivative in comparison to that of the parent-unsubstituted compound (0.47 ± 0.05 ps vs. 0.87 ± 0.09 ps) in cyclohexane.
- Subjects
DOUBLE bonds; PERMUTATION groups; ISOMERS; ULTRAVIOLET-visible spectroscopy; METHOXY group; PHOTOCHROMISM; TIME-resolved spectroscopy
- Publication
International Journal of Molecular Sciences, 2020, Vol 21, Issue 21, p7825
- ISSN
1661-6596
- Publication type
Article
- DOI
10.3390/ijms21217825