(E)-1-(Anthracen-9-yl)-3-(2-chloro-6-fluorophenyl)prop-2-en-1-one: crystal structure and Hirshfeld surface analysis

In the title compund, the enone moiety adopts an E conformation. An intramolecular C—H⋯F hydrogen bond generates an S(6) ring motif. In the crystal, molecules are arranged into centrosymmetric dimers via pairs of C—H⋯F hydrogen bonds. The crystal structure also features C—H⋯π and π–π interactions. Hirshfeld surface analysis was used to confirm the existence of intermolecular interactions.


Chemical context
The biological properties of chalcone derivatives such as anticancer (Bhat et al., 2005), antimalarial (Xue et al., 2004), anti-oxidant and antimicrobial (Yayli et al., 2006), antiplatelet (Zhao et al., 2005) as well as anti-inflammatory (Madan et al., 2000) have been studied extensively and developed. As part of our own studies in this area, we hereby report the synthesis and crystal structure of the title compound.

Hirshfeld surfaces analysis
The intermolecular interactions of the title compound can be visualized using Hirshfeld surface analysis (Wolff et al., 2012). The Hirshfeld surfaces mapped over d norm are shown in Fig. 4. The 2-D fingerprint plots showing the occurrence of different kinds of intermolecular contacts are shown in Fig. 5.
The C17-H17AÁ Á ÁF1 interactions are shown on the Hirshfeld surfaces marked with a bright-red spot for short contactsÁThe HÁ Á ÁF/FÁ Á ÁH contacts comprise 6.3% of the total Hirshfeld surface, represented by two symmetrical narrow pointed spikes with d e + d i $2.3 Å , suggesting the presence of a non-classical C-HÁ Á ÁF hydrogen bond. The HÁ Á ÁH contacts are shown on the fingerprint plot as one distinct spike with the minimum value of d e + d i . These contacts represent the largest contribution within the Hirshfeld surfaces (38.8%). The crystal packing showing the molecules arranged into centrosymmetric dimers. The H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity. Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
Detail of the crystal structure showing the C14-H14AÁ Á ÁCg1 interaction where Cg1 is the centroid of C1-C6 ring.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids. The intramolecular C-HÁ Á ÁF hydrogen bond is shown as a dashed line.
research communications Figure 4 d norm mapped on the Hirshfeld surface for visualizing the intermolecular interactions of the title chalcone compound. Dotted lines (green) represent hydrogen bonds.

Figure 5
The 2-Dimensional fingerprint plot for the title chalcone compound showing contributions from different contacts.

Figure 7
Hirshfeld surface mapped over curvedness of the chalcone compound in (a) front view and (b) back view.

Figure 6
Hirshfeld surface mapped over the shape index of the chalcone compound in (a) front view and (b) back view.
Significant C-HÁ Á Á interactions (22.8%) can be also be seen, indicated by the wings of d e + d i $2.6 Å on the fingerprint plot. The presence ofinteractions is shown as CÁ Á ÁC contacts, which contribute 8.9% of the Hirshfeld surfaces. The presence of these interactions can also be shown by the Hirshfeld surfaces mapped by shape index (Fig. 6) and the Hirshfeld surfaces mapped with curvedness ( Fig. 7).

Synthesis and crystallization
A mixture of 9-acetylanthracene (0.1 mol, 0.11 g) and 2chloro-6-fluorobenzaldehyde (0.1 mol, 0.08 g) was dissolved in methanol (20 ml). A catalytic amount of NaOH (5 ml, 20%) was added to the solution dropwise with vigorous stirring. The reaction mixture was stirred for about 5-6 h at room temperature. After stirring, the contents of the flask were poured into ice-cold water (50 ml) and the resulting crude solid was collected by filtration. The compound was dried and purified by repeated recrystallization from acetone solution, forming yellow plates.

Special details
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.