Crystal structure of (E)-1,3-bis(6-methoxynaphthalen-2-yl)prop-2-en-1-one

In the title compound, C25H20O3, the central –C(=O)—C=C– chain is disordered over two positions about the central C atom, with an occupancy ratio of 0.848 (6):0.152 (6). The molecule is twisted with the two naphthalene ring systems being inclined to one another by 52.91 (9)°. In the crystal, molecules are linked by C—H⋯π interactions, forming a three-dimensional structure. The structure was refined as a two-component twin with a 180 ° rotation about the c* axis.


S1. Comments
Heteroaryl chalcones are well documented as important synthons for a number of pharmaceutically active molecules, and extensive investigations have demonstrated the biological properties of natural and synthetic chalcones. These properties are largely attributed to the presence of the a,ß-unsaturated ketone moiety in the chalcone (Anderson & Markham, 2006;Yadav et al., 2011). Chalcones are reported to possess many useful properties, for example antibacterial [Liu et al., 2011] and antifungal [Siddiqui et al., 2012]. These compounds are important synthons for the preparation of five-and sixmembered ring systems [Powers et al., 1998] as well as intermediates in the synthesis of many pharmaceutically useful molecules [Perozo-Rondon et al., 2006]. Given such varied pharmacological activities and synthetic utilities, chalcones have always attracted chemists to develop newer molecules and study their biological activities. Adding to the list of active heteroaryl chalcones for use in pharmaceutical applications and as an effective synthon for the preparation of fiveand six-member ring systems, we report herein on the synthesis and crystal structure of the title compound.
In the crystal, molecules are linked by C-H···π interactions forming a three-dimensional structure. There are no other intra-or inter-molecular interactions present.

S2. Synthesis and crystallization
To a stirred solution of 6-methoxy-2-naphthaldehyde (1.86 g, 10 mmol) in ethanol (10 ml), 1-(6-methoxynaphthalen-2-yl) ethanone (2.00 g, 10 mmol) dissolved in ethanol (10 ml) was added portion wise. The reaction mixture was stirred at room temperature for an additional 20 min, during which time it turned to a homogeneous solution. KOH solution (40%, 2 ml) was then added drop wise and the resultant mixture was stirred at room temperature for 2 h. The precipitated product was then collected by filtration and purified by recrystallization from chloroform-methanol (1:1 v/v, 10 ml), to afford 2.29 g (82%) of the title compound as yellow-brown needles (m.p.: 396-397 K). Colourless block-like crystals, suitable for X-ray diffraction, were obtained by crystallization from a 1 ml saturated solution in ethanol.

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2

Figure 1
The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Only the major component of the disordered O atom is shown.

Figure 2
A view along the c axis of the crystal packing of the title compound.