Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structure of Pigment Yellow 213, C23H21N5O9

The crystal structure of the nanocrystalline phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the phase is consistent with the determined crystal structure. The Β phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the Β phase to have a columnar structure with a similar local structure as the phase and a domain size in column direction of approximately 4 nm. © 2009 International Union of Crystallography.