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

In the title compound, C27H36O3, the asymmetric unit consists of two crystallographically independent molecules. The aromatic rings form dihedral angles of 17.1 (2) and 17.6 (2)° in the two molecules. In both molecules, the enone groups adopt an s–cis conformation and the alkoxyl chains are in trans conformations curving out of the zigzag plane. Intramolecular O—H⋯O hydrogen bonds involving the keto and hydroxy groups generate S(6) ring motifs. The molecules are stacked alternately in a head-to-tail fashion along the a axis and the crystal structure is stabilized by weak C—H⋯π interactions. The crystal studied was a non-merohedral twin, the ratio of components being 0.788 (2):0.212 (2).

In the title compound, C 27 H 36 O 3 , the asymmetric unit consists of two crystallographically independent molecules. The aromatic rings form dihedral angles of 17.1 (2) and 17.6 (2) in the two molecules. In both molecules, the enone groups adopt an s-cis conformation and the alkoxyl chains are in trans conformations curving out of the zigzag plane. Intramolecular O-HÁ Á ÁO hydrogen bonds involving the keto and hydroxy groups generate S(6) ring motifs. The molecules are stacked alternately in a head-to-tail fashion along the a axis and the crystal structure is stabilized by weak C-HÁ Á Á interactions. The crystal studied was a non-merohedral twin, the ratio of components being 0.788 (2):0.212 (2).

Comment
Chalcone derivatives are of interest because of their biological properties such as anticancer (Bhat et al., 2005), antimalarial (Xue et al., 2004), antiangiogenic and antitumour (Lee et al., 2006), antiplatelet activity (Zhao et al., 2005) and antihyperglycemic activity (Satyanarayana et al., 2004). As part of our studies on their biological properties, we have synthesized the title chalcone derivative, (I). Its antibacterial activities were tested against E. coli ATCC 8739 and showed antimicrobial activity. The structure determination of (I) was carried out and is reported in this paper.
The enone moieties adopt s-cis conformation with the O2-C7-C8-C9 torsion angle being 6.5 (5)° for molecule A  (Ng et al., 2006;Razak et al., 2009;Ngaini, Fadzillah et al., 2009;. The conformation throughout the zigzag alkoxyl tails in both molecules is trans with the largest deviation from the ideal value being -174.4 (3)° for the C19A-C20A-C21A-C22A torsion angle in molecule A and -173.5 (3)° for the C17B-C18B-C19B-C20B torsion angle in B. Even though the torsion angle C16-O3-C13-C14 in each molecule is -6.8 (5)° for A and -12.2 (5)° for B, the alkoxyl chains curve out of the zigzag plane with the least-squares plane through the chain making dihedral angle with the attached benzene ring of 17.02 ( (Bernstein et al., 1995). In the crystal structure, the molecules are stacked alternately along the a axis in a head-to-tail manner (Fig. 2). In the absence of conventional hydrogen bonds, the crystal structure is stabilized by weak C-H···π interactions (Table 1).
supplementary materials sup-2 Experimental A mixture of 2-hydroxyacetophenone (2.72 ml, 20 mmol) and 4-dodecyloxybenzaldehyde (5.81 ml, 20 mmol) and KOH (4.04 g, 72 mmol) in 60 ml of methanol was heated at reflux for 10 h. The reaction was cooled to room temperature and acidified with cold diluted HCl (2 N). The resulting precipitate was filtered, washed and dried. After redissolving in hexane, followed by a few days of slow evaporation, crystals were collected.

Refinement
All H atoms were positioned geometrically and refined using a riding model. The U iso (H) values were constrained to be 1.5U eq (C,O) (methyl H and hydroxyl H atoms) and 1.2U eq (C) (other H atoms). The rotating model group was considered for the methyl group. The crystal is a twin with a refined BASF = 0.212 (2).
Figures Fig. 1. The asymmetric unit of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme. Intramolecular interactions were shown as dashed line.