Leucopterin, the white pigment in butterfly wings: structural analysis by PDF fit, FIDEL fit, Rietveld refinement, solid-state NMR and DFT-D.

Leucopterin (CHNO) is the white pigment in the wings of Pieris brassicae butterflies, and other butterflies; it can also be found in wasps and other insects. Its crystal structure and its tautomeric form in the solid state were hitherto unknown. Leucopterin turned out to be a variable hydrate, with 0.

First crystal structure of a Pigment Red 52 compound: DMSO solvate hydrate of the monosodium salt.

Pigment Red 52, Na[CHClNOS], is an industrially produced hydrazone-laked pigment. It serves as an inter-mediate in the synthesis of the corresponding Ca and Mn salts, which are used commercially for printing inks and lacquers. Hitherto, no crystal structure of any salt of Pigment Red 52 is known.

Two monosodium salt hydrates of Colour Index Pigment Red 48.

We report herein the crystal structures of a monohydrate of Colour Index Pigment Red 48 (P.R.48) (systematic name: monosodium 2-{2-[3-carboxy-2-oxo-1,2-dihydronaphthalen-1-ylidene]hydrazin-1-yl}-4-chloro-5-methylbenzenesulfonate monohydrate), Na·CHClOS·HO, and a dihydrate, Na·CHClOS·2HO.

Crystal structure of sodium ethoxide (CHONa), unravelled after 180 years.

As early as 1837, Liebig synthesised solid C2H5ONa. Today, C2H5ONa is one of the standard bases in organic synthesis. Here, we report the identification of different solid phases and the crystal structures and phase transformations of C2H5ONa and C2H5ONa·2C2H5OH.

Absolute Configuration of Pharmaceutical Research Compounds Determined by X-ray Powder Diffraction.

The absolute configuration of active pharmaceutical ingredients (APIs) was determined by generating salts of the active pharmaceutical ingredient (API) with counterions of known chirality, and determining the crystal structures by X-ray powder diffraction. This approach avoids the (often tedious) growth of single crystals, and is successful with very limited quantities of material (less than 1 mg). The feasibility of the method is demonstrated on five examples, and its limitations are discussed as well.

Crystallographic and Dynamic Aspects of Solid-State NMR Calibration Compounds: Towards ab Initio NMR Crystallography.

The excellent results of dispersion-corrected density functional theory (DFT-D) calculations for static systems have been well established over the past decade. The introduction of dynamics into DFT-D calculations is a target, especially for the field of molecular NMR crystallography. Four (13) C ss-NMR calibration compounds are investigated by single-crystal X-ray diffraction, molecular dynamics and DFT-D calculations.