20 октября, 2015 
Pokraskin Terence Chamberlain
The general class of compounds known as dioxazines, or more systematically as triphenodioxazines, exhibit colors ranging from yellow to violet, in the solid state, as a manifestation of their respective chemical and crystallographic structures [1].
The class is characterized by the parent of the series 1, a condensed pentacyclic structure in which two oxazine rings with opposite orientation are sandwiched between three aromatic carbocycles of which the central one is quininoid:
1
The symmetrical planar and conjugated quininoid structure is a very efficient chromophore, thus imparting intense coloration to those compounds of which it is a structural component.
The sulfonated derivatives of the parent structure, discovered in 1928 (Kranzlein et al., Farbewerke Hoechst), afford colorants which can be used as direct dyes on cotton, but the parent triphenodioxazine, an orange solid, has no technical importance as a colorant. It was not until 1952, however, that a tinctorially strong violet pigment derived from a 9,10-dichlorotriphenodioxazine was patented [2] and ultimately designated as Pigment Violet 23.
12.1.1
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