5-(4-Hydro­xy-3-methoxy­phenyl)-1-phenyl­pent-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.