Experimental and predicted crystal structures of Pigment Red 168 and other dihalogenated anthanthrones

The crystal structures of 4,10‐dibromo‐anthanthrone (Pigment Red 168; 4,10‐dibromo‐dibenzo[def,mno]chrysene‐6,12‐dione), 4,10‐dichloro‐ and 4,10‐diiodo‐anthanthrone have been determined by single‐crystal X‐ray analyses. The dibromo and diiodo derivatives crystallize in P21/c, Z = 2, the dichloro der...

Full description

Saved in:
Bibliographic Details
Published inActa crystallographica. Section B, Structural science Vol. 66; no. 5; pp. 515 - 526
Main Authors Schmidt, Martin U., Paulus, Erich F., Rademacher, Nadine, Day, Graeme M.
Format Journal Article
LanguageEnglish
Published 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.10.2010
Blackwell Publishing Ltd
Subjects
Online AccessGet full text

Cover

Loading…
More Information
Summary:The crystal structures of 4,10‐dibromo‐anthanthrone (Pigment Red 168; 4,10‐dibromo‐dibenzo[def,mno]chrysene‐6,12‐dione), 4,10‐dichloro‐ and 4,10‐diiodo‐anthanthrone have been determined by single‐crystal X‐ray analyses. The dibromo and diiodo derivatives crystallize in P21/c, Z = 2, the dichloro derivative in , Z = 1. The molecular structures are almost identical and the unit‐cell parameters show some similarities for all three compounds, but the crystal structures are neither isotypic to another nor to the unsubstituted anthanthrone, which crystallizes in P21/c, Z = 8. In order to explain why the four anthanthrone derivatives have four different crystal structures, lattice‐energy minimizations were performed using anisotropic atom–atom model potentials as well as using the semi‐classical density sums (SCDS‐Pixel) approach. The calculations showed the crystal structures of the dichloro and the diiodo derivatives to be the most stable ones for the corresponding compound; whereas for dibromo‐anthanthrone the calculations suggest that the dichloro and diiodo structure types should be more stable than the experimentally observed structure. An experimental search for new polymorphs of dibromo‐anthanthrone was carried out, but the experiments were hampered by the remarkable insolubility of the compound. A metastable nanocrystalline second polymorph of the dibromo derivative does exist, but it is not isostructural to the dichloro or diiodo compound. In order to determine the crystal structure of this phase, crystal structure predictions were performed in various space groups, using anisotropic atom–atom potentials. For all low‐energy structures, X‐ray powder patterns were calculated and compared with the experimental diagram, which consisted of a few broad lines only. It turned out that the crystallinity of this phase was not sufficient to determine which of the calculated structures corresponds to the actual structure of this nanocrystalline polymorph.
Bibliography:ark:/67375/WNG-LFTTHSP4-R
istex:60E9A444F80415C8C83002DF68351621C22D326D
ArticleID:AYBOG5041
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ObjectType-Article-2
ObjectType-Feature-1
ISSN:0108-7681
2052-5192
1600-5740
2052-5206
DOI:10.1107/S0108768110028247