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. Now, single crystals have been obtained of a dimethyl sulfoxide solvate hydrate of the monosodium salt of Pigment Red 52, namely, monosodium 2-[2-(3-carb-oxy-2-oxo-1,2-di-hydro-naphthalen-1-yl-idene)hydrazin-1-yl]-5-chloro-4-methyl-benz-ene-sulfonate dimethyl sulfoxide monosolvate monohydrate, Na·CHClNOS·HO·CHOS, obtained from in-house synthesized Pigment Red 52. The crystal structure was determined by single-crystal X-ray diffraction at 173 K. In this monosodium salt, the SO group is deprotonated, whereas the COOH group is protonated. The residues form chains ionic inter-actions and hydrogen bonds. The chains are arranged in polar/non-polar double layers.