(1E,4E)-1,5-Bis[2-(trifluoromethyl)phenyl]penta-1,4-dien-3-one

In the title compound, C19H12F6O, a monoketone derivative of curcumin, both double bonds have a trans conformation. The molecule is mostly planar with all C and O atoms essentially coplanar, with the exception of one benzene ring, which is tilted by 17.18 (1)° with respect to the plane of the remainder of the molecule. The r.m.s. deviation from planarity of the coplanar section is 0.0097 Å. The crystal packing features weak C—H⋯O and C—H⋯F interactions.

In the title compound, C 19 H 12 F 6 O, a monoketone derivative of curcumin, both double bonds have a trans conformation. The molecule is mostly planar with all C and O atoms essentially coplanar, with the exception of one benzene ring, which is tilted by 17.18 (1) with respect to the plane of the remainder of the molecule. The r.m.s. deviation from planarity of the coplanar section is 0.0097 Å . The crystal packing features weak C-HÁ Á ÁO and C-HÁ Á ÁF interactions.   Table 1 Hydrogen-bond geometry (Å , ). Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97.

Comment
The title compound is a bischalcone, and is a monoketone derivative of curcumin. Curcumin is a naturally abundant betadiketone derived from the rizome of curcuma longa (Buescher & Yang, 2000). Numerous studies have shown that curcumin possesses multiple pharmacological properties. Several clinical trials of curcumin were carried out in patients with pancreatic cancer, multiple myeloma, rheumatoid arthritis, cystic fibrosis, inflammatory bowel disease, psoriasis, and other disorders (Kumar et al., 2003;Hsu & Cheng, 2007). Since the stereochemistry of the synthesized molecule is an important criterion for its biological actions, it is of of desirable to establish the structure of the synthesized molecule.
Crystalline chalcone derivatives are also of interest due to their their second harmonic generation properties, particularly, their often are good blue light emitters. The NLO properties of the molecules are also associated with their molecular geometry (Fichou et al., 1988;Butcher et al., 2006), and accordingly, a single-crystal XRD study of the title bischalcone was undertaken to obtain detailed information on its molecular conformation.
The crystal packing of this molecule is stabilized by weak intermolecular C-H···O, C-H···F and C-H···π interactions (Table 1).

Special details
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 Rfactors based on ALL data will be even larger.