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

Abstract

The crystal structure of the nanocrystalline alpha 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 alpha phase is consistent with the determined crystal structure. The beta 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 beta phase to have a columnar structure with a similar local structure as the alpha phase and a domain size in column direction of approximately 4 nm.

7-Methoxy-2,3-dioxo-1,4-dihydroquinoxalin-6-aminium chloride monohydrate

“…Compound (I) is synthesized from 2,4,5-triamino-1-methoxybenzene and oxalyl chloride. Research on quinoxaline pigments led to Pigment Yellow 213 (Metz & Weber, 1998;Stengel-Rutkowski & Metz, 2000;Metz & Morgenroth, 2009;Schmidt et al, 2009) which is used in water-based automotive coatings. Compound (I) is a dull yellow powder which is poorly soluble; hence, no single crystals have, to date, been grown.…”

Total-Scattering Pair-Distribution Function of Organic Material from Powder Electron Diffraction Data

“…The PDF G(r) represents the probability of finding a pair of atoms with an interatomic distance r, weighted by the scattering power of the individual atoms (Farrow & Billinge, 2009;Egami & Billinge, 2012). Such an approach is equally applicable to amorphous and nanostructured organic materials, as recently demonstrated (Bates et al, 2006;Schmidt et al, 2009;Billinge et al, 2010;Dykne et al, 2011) where for a molecular crystal, the PDF profiles include intramolecular distances as well as the interatomic distances between different molecules.…”

Crystal structure analysis of a star-shaped triazine compound: a combination of single-crystal three-dimensional electron diffraction and powder X-ray diffraction

“…When it turned out that the powder pattern of (I) could not be indexed using conventional approaches, the single-crystal ED data was used to determine a unit cell followed by structure solution using reliable intensities from powder X-ray data. A similar approach was used by Schmidt et al (2009).…”