Crystal structure and morphology of the bright orange γ-phase of Pigment Red 53:2 from XRPD, DFT+D and TEM

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt

  • Jacco van de Streek
  • Tatiana E. Gorelik
  • Martin U. Schmidt

Pigment Red 53:2 (P R.53:2), the calcium lake of P.R.53, in its γ-phase is a bright orange pigment suitable for printing applications and for the colouration of seeds. The γ-phase forms needle-like, long thin crystals, which are often bent, as seen by transmission electron microscopy (TEM). Its crystal structure was determined from synchrotron X-ray powder diffraction data supported by lattice-energy minimisations with dispersion-corrected density functional theory (DFT+D). The γ-phase is a dihydrate with the chemical composition Ca(C17H12ClN2O4S)2 · 2H2O. The calcium ion is coordinated by seven oxygen atoms, which come from the sulfonate groups of four anions, one carbonyl group and two water molecules. The structure contains columns which are built by the Ca2+ ions, the water molecules, and the pigment anions, with their sulfonate and carbonyl groups directed inward, and their non-polar phenyl and naphthalene groups pointing outwards. All columns are parallel. Neighbouring columns are connected by van der Waals forces only. This explains the observed bent hair-like morphology of the crystals.

OriginalsprogEngelsk
Artikelnummer109456
TidsskriftDyes and Pigments
Vol/bind196
Antal sider10
ISSN0143-7208
DOI
StatusUdgivet - 2021

Bibliografisk note

Funding Information:
The Villum Foundation (Denmark) is gratefully acknowledged for financial support (project No. VKR023111). TEG thanks the financial support from DFG project CRC 1279.

Funding Information:
The authors thank Frank Becker (Clariant, now Colorants Solutions Deutschland GmbH, Frankfurt am Main) for the synthesis of P.R.53:2. Fabia Gozzo (now at Excelsus) is gratefully acknowledged for the collection of the synchrotron X-ray diffraction powder data at SLS. We are grateful to Ute Kolb (University of Mainz, Germany) and Ute Kaiser (University of Ulm, Germany) for providing electron microscopy instrumentation. We thank Manuel Mundszinger (University of Ulm, Germany) for his support with SEM imaging. The Villum Foundation (Denmark) is gratefully acknowledged for financial support (project No. VKR023111). TEG thanks the financial support from DFG project CRC 1279. Final remark: According to our experience with our preceeding manuscript, the layout process is not carefully done at Elsevier. Hence, this manuscript must not be published online in its present state.

Publisher Copyright:
© 2021

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