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A new look at two polymorphic crystal structures of dibenzoylmethane: relationship between the crystal packing and the hydrogen atom position revealed by quantum chemistry and quantum crystallography methods
Author(s) -
Wojtulewski Sławomir,
Strawa Jakub Wladyslaw,
Tomczyk Michal,
Gawel Magdalena,
Brzezinski Krzysztof
Publication year - 2020
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/s2052520620012196
Subject(s) - dibenzoylmethane , orthorhombic crystal system , tautomer , monoclinic crystal system , chemistry , crystallography , crystal structure , density functional theory , atom (system on chip) , crystal (programming language) , hydrogen atom , hydrogen bond , molecule , computational chemistry , stereochemistry , group (periodic table) , organic chemistry , computer science , programming language , embedded system
Chalcones, including dibenzoylmethane, are an important subgroup of natural polyphenolic compounds that exhibit a wide spectrum of pharmacological and industrial applications. Dibenzoylmethane was isolated from Hottonia palustris L. (Primulaceae). The compound was crystallized in two polymorphic forms: in monoclinic space group P 2 1 / c and orthorhombic space group Pbca . Crystal structures of the polymorphs were solved and refined against diffraction data measured at 100 and 293 K. In both crystal structures, the chalcone occurs in its keto–enol tautomeric form with the hydroxyl H atom mutually bound by two oxygen atoms rather than covalently attached to a particular oxygen atom. To explain this phenomenon in more detail, density functional theory and quantum theory of atoms in molecules based quantum chemistry calculations were applied. Additionally, high‐resolution experimental data of very high quality measured for the monoclinic and orthorhombic crystals at 100 K allowed the engagement of the quantum crystallography method, based on Hirshfeld atom refinement, to determine the position of each individual H atom. It is suggested that the presence of the particular tautomeric form of dibenzoylmethane with a centred H atom position results from the π‐stacking interaction between the phenyl ring and the malondialdehyde quasi‐ring causes delocalization of the electron density in the latter.