Control of the Switching Speed of Photochromic Naphthopyrans through Restriction of Double Bond Isomerization

An efficient synthesis of photochromic fused-naphthopyrans was developed. UV–vis or sunlight irradiation of these uncolored compounds in solution led to the formation of a single colored photoisomer along with an unusual and uncolored bicyclic compound formed through an intramolecular photochemical...

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Bibliographic Details
Published in:Journal of organic chemistry 2017-12, Vol.82 (23), p.12028-12037
Main Authors: Sousa, Céu M, Berthet, Jerome, Delbaere, Stephanie, Polónia, André, Coelho, Paulo J
Format: Article
Language:English
Subjects:
Chemical Sciences
or physical chemistry
Theoretical and
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Summary:An efficient synthesis of photochromic fused-naphthopyrans was developed. UV–vis or sunlight irradiation of these uncolored compounds in solution led to the formation of a single colored photoisomer along with an unusual and uncolored bicyclic compound formed through an intramolecular photochemical Diels–Alder reaction. Both species faded thermally in the dark to the initial form. A mechanism for this transformation is proposed based on NMR studies of irradiated solutions. The new fused-naphthopyrans have been incorporated into hybrid organic–inorganic matrices affording light-yellow materials that develop intense red colorations under UV light and return to the initial uncolored state in just a few seconds, in the dark, at room temperature. These results are useful for the development of fast switching materials used in the production of photochromic lenses.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.7b01669