| Summary: | Fingerprint plots of Hirshfeld surfaces were used to locate and analyze the deficiencies in various methodologies employed in the determination of the relative energies of five polymorphs of 1,8-dihydroxyanthraquinone. Nine crystallographically independent molecules were characterized by X-ray crystallography and Hirshfeld surfaces were derived from the X-ray structures. The space groups and number of independent molecules (Z') for each of the polymorphs (1-5) is as follows: (1) P41 (or P43),Z' ) 1; (2) Pca21, Z' ) 2; (3) P1 j, Z' ) 4; (4) P21/n, Z' ) 1; (5) P41212 (or P43212), Z' ) 0.5. Form 1 is the most thermodynamically stable among the reproducible structures, as established by competitive solubility tests, followed by 2 and then 4. The unrestrained structures of the five polymorphs were computed using the CVFF and COMPASS force fields as well as with the density functionalcode, SIESTA.
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