(E)-3-(4-Ethoxyphenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one

In the title compound, C17H16O3, the carbonyl group is in an s-cis configuration with respect to the olefinic double bond. The dihedral angle between the two benzene rings is 2.85 (3)°. The prop-2-en-1-one bridge makes dihedral angles of 4.77 (4) and 4.15 (4)°, respectively, with the 2-hydroxyphenyl and 4-ethoxyphenyl rings. The ethoxy group is coplanar with the attached phenyl ring [Car—O—C—C = 179.72 (5)°]. An intramolecular O—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal structure, molecules are stacked in an antiparallel manner to form columns along the b axis. The columnar structure is stabilized by C—H⋯π interactions involving the 2-hydroxyphenyl ring.

In the title compound, C 17 H 16 O 3 , the carbonyl group is in an scis configuration with respect to the olefinic double bond. The dihedral angle between the two benzene rings is 2.85 (3) . The prop-2-en-1-one bridge makes dihedral angles of 4.77 (4) and 4.15 (4) , respectively, with the 2-hydroxyphenyl and 4ethoxyphenyl rings. The ethoxy group is coplanar with the attached phenyl ring [C ar -O-C-C = 179.72 (5) ]. An intramolecular O-HÁ Á ÁO hydrogen bond generates an S(6) ring motif. In the crystal structure, molecules are stacked in an antiparallel manner to form columns along the b axis. The columnar structure is stabilized by C-HÁ Á Á interactions involving the 2-hydroxyphenyl ring.

Comment
Chalcones is an interesting class of compounds which have been reported to posses various useful properties such as nonlinear optical (NLO)  and fluorescent properties (Svetlichny et al., 2007). Synthetic and naturally occurring chalcones have been found to exhibit many useful biological activities, including anti-inflammatory, antileishmanial, antimicrobial, antioxidant (Nowakowska, 2007;Saydam et al., 2003), HIV-1 protease inhibitory (Tewtrakul et al., 2003) and tyrosinase inhibitory (Jun et al., 2007) activities. Our on going research on NLO properties and bioactivities of the synthetic chalcones led us to synthesize the title chalcone in order to study its NLO properties, antibacterial and tyrosinase inhibitory activities. The results show that the title compound, (I), crystallized in centrosymmetric P1 space group which prohibits the second order NLO properties. Our biological testing found that (I) was inactive against the tested bacteria which are Gram-positive bacteria i.e. Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus,

Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus faecalis and Gram-negative bacteria
i.e. Pseudomonas aeruginosa, Salmonella typhi and Shigella sonnei. Nevertheless (I) shows moderate tyrosinase inhibitory activity which will be reported elsewhere with some other chalcones. Herein the crystal structure of (I) is reported.
In the crystal packing, the molecules are stacked in an antiparallel manner into columns along the b axis (Fig. 2). This arrangement is stabilized by C-H···π interactions (Table 1) involving the hydroxy phenyl ring. In addition C···O short contacts [3.2894 (8)-3.4003 (9) Å] were also observed.
After stirring for 3 h, 20% H 2 SO 4 (aq) (5 ml) was added dropwise into the solution. After the reaction mixture was kept at room temperature for a day, a yellow solid appeared and was then collected by filtration, washed with acetone and dried in air. Yellow block-shaped single crystals of the title compound suitable for X-ray structure determination were recrystalized from acetone by slow evaporation of the solvent at room temperature after several days (m.p. 387-388 K).
supplementary materials sup-2 Refinement Hydroxyl H atom was located in a difference map and refined isotropically. The remaining H atoms were placed in calculated positions, with C-H = 0.93 Å, U iso = 1.2U eq (C) for aromatic and CH, C-H = 0.96 Å, U iso = 1.2U eq (C) for CH 2 , and C-H = 0.97 Å, U iso = 1.5U eq (C) for CH 3 atoms. A rotating group model was used for the methyl groups. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme. Intramolecular O-H···O hydrogen bond is shown as a dashed line.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (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 > σ(F 2 ) is used only for calculating Rfactors(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.