(2E)-3-(2-Fluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one

In the title compouund, C15H10F2O, the molecule exists in an E conformation with respect to the C=C bond [1.3382 (16) Å]. The dihedral angle between the fluoro-substituted benzene rings is 6.80 (6)° and the whole molecule is roughly planar (r.m.s. deviation for the non-H atoms = 0.069 Å). In the crystal, molecules are linked by C—H⋯F and C—H⋯O interactions into sheets lying parallel to the bc plane.

In the title compouund, C 15 H 10 F 2 O, the molecule exists in an E conformation with respect to the C C bond [1.3382 (16) Å ]. The dihedral angle between the fluoro-substituted benzene rings is 6.80 (6) and the whole molecule is roughly planar (r.m.s. deviation for the non-H atoms = 0.069 Å ). In the crystal, molecules are linked by C-HÁ Á ÁF and C-HÁ Á ÁO interactions into sheets lying parallel to the bc plane.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009  In continuation of our work on synthesis of chalcone derivatives (Fun et al., 2012), the title compound (I) has been prepared and its crystal structure is now reported.

Experimental
To a mixture of 4-fluoroacetophenone (1.38 g, 0.01 mol) and 2-fluorobenzaldehyde (1.05 ml, 0.01 mol) in ethanol (100 ml), 15 ml of 10% sodium hydroxide solution was added and stirred at 0-5 °C for 3 h. The precipitate formed was collected by filtration and purified by recrystallization from ethanol. Colourless blocks were grown from methanol solution by the slow evaporation method (M.P.: 351 K).

Refinement
All the H atoms were positioned geometrically and refined using a riding model with U iso (H) = 1.2 U eq (C) (C-H = 0.95 Å).

Figure 2
The crystal packing of the title compound, viewed along the b axis.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.