Single crystal X-ray structure of the artists' pigment zinc yellow

• Published in: Journal of molecular structure 2017-08, Vol.1141, p.322-327
• Main Authors: Simonsen, Kim Pilkjær, Christiansen, Marie Bitsch, Vinum, Morten Gotthold, Sanyova, Jana, Bendix, Jesper
• Format: Article
• Language: English
• Subjects: Artists' pigment; FTIR; H3O2; PXRD; X-ray structure; Zinc yellow
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2017.03.108

The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2− moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type. [Display omitted] •Single crystal X-ray structure analysis of the artists' pigment zinc yellow.•Characterisation of zinc yellow by Raman, SEM-EDS, ATR-FTIR and PXRD.•Discovery of a unique structure among chromate based pigments.