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Structure of Pigment Yellow 181 dimethylsulfoxide N ‐methyl‐2‐pyrrolidone (1:1:1) solvate from XRPD + DFT‐D
Author(s) -
van de Streek Jacco
Publication year - 2015
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520615000724
Subject(s) - rietveld refinement , triclinic crystal system , crystal structure , crystallography , density functional theory , powder diffraction , hydrogen bond , molecule , valence (chemistry) , materials science , chemistry , computational chemistry , organic chemistry
With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal‐structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N ‐methyl‐2‐pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom, was determined in three stages by a combination of simulated annealing, partial Rietveld refinement with dummy atoms replacing the solvent molecules and further simulated annealing. The θ phase not being of commercial interest, additional experiments were not economically feasible and additional dispersion‐corrected density functional theory (DFT‐D) calculations were employed to confirm the correctness of the crystal structure. After the correctness of the structure had been ascertained, the bond lengths and valence angles from the DFT‐D minimized crystal structure were fed back into the Rietveld refinement as geometrical restraints (`polymorph‐dependent restraints') to further improve the details of the crystal structure; the positions of the H atoms were also taken from the DFT‐D calculations. The final crystal structure is a layered structure with an elaborate network of hydrogen bonds.