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Synthesis of a Photochromic Fused 2 H ‐Chromene Capable of Generating a Single Coloured Species
Author(s) -
Sousa Céu M.,
Pina João,
Seixas de Melo João,
Berthet Jerome,
Delbaere Stephanie,
Coelho Paulo J.
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201101702
Subject(s) - chemistry , photochromism , pyran , ring (chemistry) , double bond , kinetics , photochemistry , benzene , irradiation , stereochemistry , organic chemistry , physics , quantum mechanics , nuclear physics
A new photochromic fused 2 H ‐chromene that has a dehydropyran bridge between the pyran double bond and the benzene ring was prepared. Unlike standard 2 H ‐chromenes that give rise to two coloured species (one short‐ and one long‐lived) under UV irradiation, flash photolysis studies on this particular 2 H ‐chromene show that the opening of the pyran ring led to the formation of a single, coloured, open species that bleaches to the uncoloured initial form in <1 ms. The design of this fused 2 H ‐chromene avoids the formation of the undesirable long‐lived, transoid–trans , coloured, open form; therefore, the colour fades very quickly, according to monoexponential kinetics, without the persistence of any residual colour commonly observed in 2 H ‐chromenes. Acid treatment of 4‐[(ethoxycarbonyl)methyl]‐2 H ‐chromenes led to the formation of lactones.