Thermochromism systems

Mancini, I. Guella, G. Ddjitus, C. Duhet, D. Pietra, F. (1994A)Imidazolone and imidazolidinraie artifacts of a pivotal imidazolthiwje, zyzzin, from the poecilosclerid sponge Zyzza massalis fixHn the Coral Sea. The first thermochromic systems of marine wigin. Helv. Chim. Acta, 77, 1886-94. 

Chapter 8 (Perimidinespirocyclohexadienones). This series constitutes a rather new photochromic or thermochromic system based on proton transfer involving valence and prototropic tautomeric intramolecular reactions (Scheme 8). 

Thermochromic systems will not be considered here, and we will assume that the product A is stable. 

F. M. Menger and M. Perinis, Acid catalysis in a thermochromic system Tetrahedron Lett. 47,... 

Aitken, D., Burkinshaw, S.M., Grifiths, J., Towns, A.D., 1996h. Textile apphcations of thermochromic systems. Review in Progress of Coloration 26 (1), 1478—4491. 

Maclaren, D.C., White, M.A., 2003h. Competition between dye-developer and solvent-developer interaction in a reversible thermochromic system. Journal of Materials Chemistry 13, 1701-1704. 

A phase-change thermochromic system has been designed through the reversible transformation of the 4-substituted flavylium dye... 

The most widely-used industrial thermochromic system is the referred to as the leuco dye type. The term leuco describes a dye that can acquire two forms, one of which is colourless. This micro-encapsulated composite system relies on colour formation from the interaction of three materials a colour former (the leuco dye), an acidic developer and a low-melting, non-volatile hydrophobic solvent, a set of ingredients similar to those used in thermally-sensitive paper as described above. However, in the leuco dye thermochromic systems, it is curious that, even though similar chemistry is involved, the composite material is coloured at low temperatures and decolourises as the temperature is raised. To explain this effect, a mechanism illustrated in simplified form in Scheme 11.4 has been proposed. At temperatures below the melting point of the solvent, the system is heterogeneous with the colour former existing as the coloured... 

Scheme 11.4 Schematic representation of the mechanism of colour change in a microencapsulated leuco dye thermochromic system.

This methodology can also be extended to other thermochromic systems based either on nickel (13), cobalt (14) or other metals (15) and non-metals (16). 

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