Formation of a leuco Spirolactone from 4-(2-Carboxyphenyl)-7-diethylamino-4′-dimethylamino-1-benzopyrylium: Design of a Phase-Change Thermochromic System Based on a Flavylium Dye
✍ Scribed by Raquel Gavara; César A. T. Laia; A. Jorge Parola; Fernando Pina
- Book ID
- 101840266
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 395 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
A phase‐change thermochromic system was designed through the reversible transformation of the 4‐substituted flavylium dye 4‐(2‐carboxyphenyl)‐7‐diethylamino‐4′‐dimethylamino‐1‐benzopyrylium into its leuco form, in the presence of a developer (ethyldiisopropylamine) and a suitable solvent (e.g., acetonitrile, n‐pentadecanonitrile). The leuco form of the flavylium‐based dye is a spirolactone species whose ring opens at low temperature (below the solvent melting point) to form the blue flavylium cation. Decarboxylation of the lactone to give 4‐phenyl‐7‐diethylamino‐4′‐dimethylamino‐1‐benzopyrylium was observed upon irradiation of the system with UV light, erasing the thermochromic effect.