(E)-1-[4-(Hexyloxy)phenyl]-3-(2-hydroxyphenyl)prop-2-en-1-one

In the title compound, C21H24O3, the enone moiety adopts an s-cis conformation and the dihedral angle between the benzene rings is 12.89 (6)°. The hexyloxy tail adopts an extended conformation. In the crystal, inversion dimers are linked by pairs of O—H⋯O hydrogen bonds and pairs of C—H⋯O interactions, forming two R 2 2(7) and one R 2 2(10) loops. The dimers are then arranged into sheets lying parallel to (201) and weak C—H⋯π interactions consolidate the packing.

In the title compound, C 21 H 24 O 3 , the enone moiety adopts an s-cis conformation and the dihedral angle between the benzene rings is 12.89 (6) . The hexyloxy tail adopts an extended conformation. In the crystal, inversion dimers are linked by pairs of O-HÁ Á ÁO hydrogen bonds and pairs of C-HÁ Á ÁO interactions, forming two R 2 2 (7) and one R 2 2 (10) loops. The dimers are then arranged into sheets lying parallel to (201) and weak C-HÁ Á Á interactions consolidate the packing.

Related literature
For a related structure and background to the biological properties of chalcones, see: Ngaini et al. (2011). For related structures, see: Razak et al. (2009);Ngaini et al. (2010). For graph-set theory, see: Bernstein et al. (1995). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 Table 1 Hydrogen-bond geometry (Å , ).

Experimental
A mixture of 2-hydroxybenzaldehyde (1.46 ml, 12 mmol), and 4-hexyloxyacetophenone (2.64 g, 12 mmol) and KOH (2.42 g, 43 mmol) in methanol (50 ml) was heated at reflux for 24 h. The reaction was cooled to room temperature and acidified with cold diluted HCl (2N). The resulting precipitate was filtered, washed and dried. After redissolving in hexane-ethanol (7:1) followed by few days of slow evaporation, yellow blocks were collected.

Refinement
The O-bound H atom was located in a difference Fourier map and refined freely with O-H = 0.94 (2) Å. The remaining H atoms were placed in calculated positions with C-H = 0.93-0.97 Å. The U iso values were constrained to be 1.5U eq (methyl-H atom) and 1.2U eq (other H atoms). The rotating model group was applied for the methyl group.

Figure 1
The structure of the title compound, showing 50% probability displacement ellipsoids.

Figure 2
The crystal packing, viewed along the a-axis, showing the molecules in pairs, arranged into sheets parallel to (201) plane.
Hydrogen bonds are shown as dashed lines.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.