title: Local structure in the disordered solid solution of cis- and trans-perinones.
abstract: The cis- and trans-isomers of the polycyclic aromatic compound perinone, C26H12N4O2, form a solid solution (Vat Red 14). This solid solution is isotypic to the crystal structures of cis-perinone (Pigment Red 194) and trans-perinone (Pigment Orange 34) and exhibits a combined positional and orientational disorder: In the crystal, each molecular position is occupied by either a cis- or trans-perinone molecule, both of which have two possible molecular orientations. The structure of cis-perinone exhibits a twofold orientational disorder, whereas the structure of trans-perinone is ordered. The crystal structure of the solid solution was determined by single-crystal X-ray analysis. Extensive lattice-energy minimizations with force-field and DFT-D methods were carried out on combinatorially complete sets of ordered models. For the disordered systems, local structures were calculated, including preferred local arrangements, ordering lengths, and probabilities for the arrangement of neighbouring molecules. The superposition of the atomic positions of all energetically favourable calculated models corresponds well with the experimentally determined crystal structures, explaining not only the atomic positions, but also the site occupancies and anisotropic displacement parameters.
authors.affiliation: Institut für Anorganische und Analytische Chemie der Goethe-Universität, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Jaroslav L
authors.initials: JL
authors.lastname: Teteruk
authors.affiliation: Institut für Anorganische und Analytische Chemie der Goethe-Universität, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Glinnemann
authors.affiliation: Sanofi-Aventis, D-65926 Frankfurt am Main, Germany.
authors.forename: Winfried
authors.initials: W
authors.lastname: Heyse
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Kristoffer E
authors.initials: KE
authors.lastname: Johansson
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Jacco
authors.initials: J
authors.lastname: van de Streek
authors.affiliation: Institut für Anorganische und Analytische Chemie der Goethe-Universität, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Martin U
authors.initials: MU
authors.lastname: Schmidt
keywords: density functional theory; disorder; lattice energy minimization; local structure; organic pigment