- Pigment Red 170
structures exist.
In the initial α polymorph the molecules are arranged in a herringbone pattern with extensive hydrogen bonding. The φ polymorph is more dense and more stable and produced industrially by thermal treatment in water at 130
°C under pressure. In this phase the molecules are planar and arranged in layers. Extensivehydrogen bonding exists within the layer but between layers the only interactions areVan der Waals force s. Dense crystal structures are preferred for pigments used in coatings because in the event ofPhotochemical decomposition the fragments are locked in place and are able to recombine. Research shows that by replacing theethoxy group in this compound by amethoxy group the crystal structure is less stable and in the final application and the color fades more easily. By careful selection ofsubstituent s it is possible to optimize crystal structure and improve optical properties Ref|Schmidt.References
# "Crystal Structures of Pigment Red 170 and Derivatives, as Determined by X-ray Powder Diffraction " Martin U. Schmidt, Detlef W. M. Hofmann, Christian Buchsbaum, Hans Joachim Metz,
Angewandte Chemie International Edition Volume 45, Issue 8 , Pages 1313 - 1317 2006 [http://dx.doi.org/10.1002/anie.200502468 Abstract]
Wikimedia Foundation. 2010.