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

In the title molecule, C18H18O4, the C=C bond of the central enone group adopts a trans conformation. The relative conformation of the C=O and C=C bonds is s-cisoid. The dihedral angle between the planes of the benzene rings is 29.49 (12)°. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into chains along [010].

In the title molecule, C 18 H 18 O 4 , the C C bond of the central enone group adopts a trans conformation. The relative conformation of the C O and C C bonds is s-cisoid. The dihedral angle between the planes of the benzene rings is 29.49 (12) . In the crystal, weak C-HÁ Á ÁO hydrogen bonds link the molecules into chains along [010].   Table 1 Hydrogen-bond geometry (Å , ). Symmetry codes: (i) Àx; Ày þ 1; Àz þ 2; (ii) x; y þ 1; z.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5590).  (Shenvi et al. 2013), anti-microbial (Sharma et al. 2012), anti-diabetic (Hsieh et al. 2012) and anti-inflammatory (Sashidhara et al. 2011). As a part of our studies on the substituent effects of chalcones on structures and biological activities (Jo et al., 2012;Hwang et al., 2011), the title compound was synthesized and its crystal structure was determined.
The molecular structure of the title compound is shown in Fig. 1. The trans configuration of C2═C3 double bond is defined by the dihedral angle of -177.9 (2) Å for C1-C2-C3-C4. The relative conformation of two double bonds, O1═C1 and C2═C3, is s-cisoid with a torsion angle of -12.8 (4)° for O1-C1-C2-C3. The orientations of the three methoxy groups can be defined by the torsion angles C9 The dihedral angle between the benzene rings is 29.49 (12)°. In the crystal, weak C-H···O hydrogen bonds links the molecules into chains along [010] (Fig. 2). Some examples of methoxy substituted chalcone structures have been published (Wu et al., 2012;Carvalho-Jr et al., 2011).

Experimental
To a solution of 3-methoxybenzaldehyde (136 mg, 1 mmol) in 20 ml of ethanol was added 3,5-dimethoxyacetophenone (180 mg, 1 mmol) and the temperature was adjusted to around 276 K in an ice-bath. To the cooled reaction mixture was added 1 ml of 50% aqueous KOH solution, and the reaction mixture was stirred at room temperature for 20 h. This mixture was poured into iced water (30 ml) was acidified (pH =3) with 3 N HCl solution to give a precipitate. Filtration and washing with water afforded crude solid of the title compound (240 mg, 79%). Recrystallization of the solid in ethanol gave pale yellow crystals which were suitable for X-ray diffraction (mp: 363-364 K).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.0722 (