(E)-1-(4,4′′-Difluoro-5′-methoxy-1,1′:3′,1′′-terphenyl-4′-yl)-3-(4-nitrophenyl)prop-2-en-1-one

In the title compound, C28H19F2NO4, a polysubstituted terphenyl derivative bearing a Michael system, the C=C double bond has an E configuration. Two C—H⋯F contacts connect molecules into inversion dimers. In addition, a C–H⋯π as well as a C–F⋯π contact can be identified. The shortest centroid–centroid distance between two aromatic rings is 3.9535 (8) Å, between one of the para-fluorobenzene rings and its symmetry-generated equivalent.

In the title compound, C 28 H 19 F 2 NO 4 , a polysubstituted terphenyl derivative bearing a Michael system, the C C double bond has an E configuration. Two C-HÁ Á ÁF contacts connect molecules into inversion dimers. In addition, a C-HÁ Á Á as well as a C-FÁ Á Á contact can be identified. The shortest centroid-centroid distance between two aromatic rings is 3.9535 (8) Å , between one of the para-fluorobenzene rings and its symmetry-generated equivalent.

Comment
Chalcones constitute an important family of substances belonging to flavonoids, a large group of natural and synthetic products with interesting physicochemical properties, biological activity and structural characteristics. They have been reported to possess many interesting pharmacological activities (Dhar, 1981) including anti-inflammatory, antimicrobial, antifungal, antioxidant, cytotoxic, antitumor and anticancer activities (Dimmock et al., 1999;Satyanarayana et al., 2004). In recent years, it has been reported that some terphenyls exhibit considerable biological activities (e.g. being potent anticoagulants, immunosuppressants, antithrombotics, neuroprotectives, specific 5-lipoxygenase inhibitors) and showing cytotoxic activities (Liu, 2006). In view of the pharmacological importance of terphenyls and chalcones, and in continuation of our work on synthesis of various derivatives of 4,4'-difluoro chalcone /b, Fun et al., 2010a/b, Jasinski et al., 2010a/b, Baktır et al., 2011a, the molecular and crystal structure of the title compound is reported.
The C=C double of the Michael system is (E)-configured. The least-squares planes defined by the carbon atoms of the para-fluoro phenyl rings of the terphenyl moiety and its central phenyl ring enclose angles of 40.43 (6)° and 43.99 (6)°, respectively. The plane defined by the atoms of the nitro group is tilted by 13.56 (19)° with respect to the plane of the aromatic system it is bonded to (Fig. 1).
In the crystal, C-H···F contacts whose range falls by more than 0.1 Å below the sum of van-der-Waals radii of the corresponding atoms are observed. These are supported by one of the hydrogen atoms in ortho position to a fluorine atom whose symmetry-generated equivalent acts as acceptor for this type of contact. In total, the molecules are connected to centrosymmetric dimers (Fig. 2). In terms of graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the descriptor for the C-H···F contacts is R 2 2 (8) on the unitary level. In addition, a C-H···π as well as a C-F···π contact can be identified. The shortest intercentroid distance between two aromatic systems is apparent between two of the para-fluoro phenyl moieties that are also part of the C-H···F contacts and was measured at 3.9535 (8) Å. Details about metrical parameters of the intermolecular contacts and their symmetry can be found in Table 1.
The packing of the title compound in the crystal is shown in Figure 3.
The precipitate formed was collected by filtration and purified by recrystallization from ethanol (yield: 80%). Single crystals suitable for the X-ray diffraction study were grown from DMF-ethanol (v:v 1:1) by slow evaporation at room temperature.