Average structures of the disordered β-phase of Pigment Red 170: a single-crystal X-ray diffraction study

Rangana Warshamanage, Anthony Linden, Martin U. Schmidt, Hans-Beat Bürgi
  • Acta Crystallographica Section B Structural Science Crystal Engineering and Materials, March 2014, International Union of Crystallography
  • DOI: 10.1107/s2052520614000407

Crystal structure of beta-Pigment Red 170

What is it about?

beta-Pigment Red 170 is a colourant used in plastics. The colour fades over time in sunlight. Understanding the local arrangement of the molecules in the material may allow new materials with better light-stability to be developed. The crystal structure is highly disordered due to variations in the layer stacking of the planar molecules. This paper presents the elucidation of the average crystal structure for the pigment.

Why is it important?

The X-ray diffraction pattern from a single crystal displays very strong rods of diffuse scattering, so that some of the Bragg reflections are barely distinguishable from the diffuse signals. Routing crystal structure analysis is at the limit of what it can do to obtain the average structure of this material. Two possible average structure models were found and it cannot easily be decided which description is the most appropriate one. Is there even a classic average structure in this case?

The following have contributed to this page: Anthony Linden

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