5-(4-hydroxy-3-methoxyphenyl)-1-phenyl-pent-4-ene-1,3-dione

In the crystalline state, the title molecule, C18H16O4, exists in the enolized form and displays a strong intramolecular hydrogen bond. The molecular structure, as well as theoretical calculations, support the hypothesis that the conjugation in the molecule is a determining factor for the position of the enol H atom. The packing of the molecules is dominated by interactions between 3-methoxy-4-hydroxyphenyl- and enol groups, thus forming planar molecular chains. These interactions include normal O-H...O bonds, as well as weak C-H...O interactions and van der Waals forces.