(2E)-3-(1,3-Diphenyl-1H-pyrazol-4-yl)-1-phenylprop-2-en-1-one

In the title compound, C24H18N2O, the pyrazole ring is essentially planar [maximum deviation = 0.004 (1) Å] and makes dihedral angles of 18.07 (4), 48.60 (4) and 9.13 (5)° with the phenyl rings. In the crystal, adjacent molecules are connected via intermolecular C—H⋯O hydrogen bonds, forming dimers. Furthermore, the crystal structure is stabilized by weak C—H⋯π and π–π interactions, with centroid–centroid distances of 3.6808 (5) Å.


Comment
Pyrazoles are a novel class of heterocyclic compounds possessing wide variety of applications in the agrochemical and pharmaceutical industries (Patel et al., 2004). Derivatives of pyrazoles are found to show good antibacterial (Isloor et al., 2009;Vijesh et al., 2010), anti-inflammatory (Sharma et al., 2010), analgesic (Rostom et al., 2003), anticancer, radioprotective (Ghorab et al., 2010) and anti-convulsant activities (Amnekar et al., 2010). Prompted by these diverse activities of pyrazole derivatives, we have synthesized the title compound to study its crystal structure.

Experimental
To a cold stirred mixture of methanol (20 ml) and sodium hydroxide (12.09 mmol) was added acetophenone (4.03 mmol). The reaction mixture was stirred for 10 min. To this solution was added formyl pyrazole (4.03 mmol) followed by tetrahydrofuran (30 ml). The solution was further stirred for 2 h at 0 °C and then at room temperature for 5 h. It was then poured into ice cold water. The resulting solution was neutralized with diluted HCl. The solid that separated out was filtered, washed with water, dried and crystallized from ethanol. Yield: 1.15 g, 81.5 %. M. p.: 406-408 K (Sharma et al., 2010).

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

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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.