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Ultrafast Dynamics of the Transoid‐ cis Isomer Formed in Photochromic Reaction from 3 H ‐Naphthopyran
Author(s) -
Brazevic Sabina,
Baranowski Mikołaj,
Sikorski Marek,
Rode Michał F.,
Burdziński Gotard
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000294
Subject(s) - photochromism , photoisomerization , isomerization , intersystem crossing , photochemistry , chemistry , ultrafast laser spectroscopy , excited state , singlet state , spectroscopy , organic chemistry , physics , quantum mechanics , nuclear physics , catalysis
Recent efforts in designing new 3 H ‐naphthopyran derivatives have been focused on efficient coloration process with a short fading time of the colored transoid‐ cis TC isomer. It is desirable to avoid photoisomerization of TC leading to transoid‐ trans TT isomers in the photoreaction. Long lifetime of TT can hamper fast applications such as dynamic holographic materials and molecular actuators, the residual color is one of the serious issues for photochromic lenses. Herein we characterize the photophysical and photochemical channels of TC excited state deactivation competing with the unwanted TC → TT isomerization process. Transient absorption spectroscopy reveals a very short lifetime of the singlet excited TC (≈0.8 ps) and its deactivation channels as S 1 →S 0 internal conversion (major), intersystem crossing S 1 →T 1 , pyran ring formation, photoenolization and TC → TT isomerization. Computations support the S 1 →S 0 and T 1 →S 0 channels as responsible for photostabilization of the TC form.