(2E)-1-(3,5-Dihydroxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one

In the title compound, C16H14O4, the benzene rings are inclined to one another by 4.91 (7)°. The conformation about the C=O and C=C bonds is trans and cis, respectively. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(14) ring motif. The dimers are linked via O—H⋯O and C—H⋯O hydrogen bonds, forming undulating two-dimensional networks lying parallel to (10-1). These networks are linked by further C—H⋯O hydrogen bonds, forming a three-dimensional structure.


Comment
Chalcones are one of the secondary metabolites in plants and belong to a class of flavonoid. They have shown diverse biological activities including anticancer (Shenvi et al., 2013), antimicrobial (Sharma et al. 2012), antidiabetic (Hsieh et al., 2012) and antiinflammatory (Sashidhara et al., 2011). As part of our attempt to investigate how the substituent effects of chalcones effect the biological activities of various compounds, the title compound was synthesized and its crystal structure is reported herein.
The molecuar structure of the title compound is illustrated in Fig. 1. The bond lengths (Allen et al., 1987) and bond angles are within normal values. The benzene rings (C1-C6 and C10-C15) are inclined to one another by 4.91 (7) °. The torsion angles about the C7═O1 and C8═C9 bonds confirm the trans and cis conformations of the respective bonds. The C8═ C9 bond distance is 1.332 (2) Å, and is in good agreement with the value [1.329 (3) Å] reported for a similar structure (Ahn et al., 2013). The methoxy C atom and hydroxy O atoms are almost coplanar with the benezene ring to which they are attached. The bond angles C4-C7-C8 = 120.4 (1)° and C8-C9-C10 = 128.2 (1)° differ slightly from the normal values but are comparable with the values reported for a similar structure (Jasinski et al., 2011).
In the crystal, molecules are linked by O-H···O hydrogen bonds forming inversion dimers with a graph set motif of R 2 2 (14) [Bernstein et al., 1995]. The dimers are linked by O-H···O and C-H···O hydrogen bonds forming undulating twodimensional networks lying parallel to (10-1) [ Fig. 2 and Table 1]. These networks are linked by further C-H···O hydrogen bonds forming a three-dimensional structure (Table 1).

Experimental
The title compound was syntheized by the base catalyzed Claisen-Schmidt reaction according to the published procedures (Shettigar et al., 2006;Patil et al., 2007). In a 250 ml round-bottomed flask 3,5-hydroxyacetophenone (0.05 mol) and 4methoxybenzaldehyde (0.05 mol) were placed and 120 ml of absolute alcohol were added. The mixture was stirred at room temperature for 5 min. Then 20 ml of 20% sodium hydroxide solution was added and the mixture was stirred for 2 h. The precipitate generated by adding a sufficient amount of dilute hydrochloric acid was filtered, washed with water and dried. The crude product was recrystallized twice from absolute alcohol yielding colourless block-like crystals (Yield 79%; M.p. 477 K).  The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
The crystal packing of the title compound viewed along the a axis. The dashed lines indicate the hydrogen bonds (see Table 1 for details). Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.