2-{5-[2-(4-Nitrophenoxy)phenyl]-1-phenyl-1H-pyrazol-3-yl}phenol

In the title compound, C27H19N3O4, the phenol and pyrazole rings are almost coplanar [dihedral angle = 0.95 (12)°] due to an intramolecular O—H⋯N hydrogen bond, whereas the phenyl ring is tilted by 40.81 (7)° with respect to the plane of the pyrazole ring. The aromatic ring with a nitrophenoxy substituent makes a dihedral angle of 54.10 (7)° with the pyrazole ring.

In the title compound, C 27 H 19 N 3 O 4 , the phenol and pyrazole rings are almost coplanar [dihedral angle = 0.95 (12) ] due to an intramolecular O-HÁ Á ÁN hydrogen bond, whereas the phenyl ring is tilted by 40.81 (7) with respect to the plane of the pyrazole ring. The aromatic ring with a nitrophenoxy substituent makes a dihedral angle of 54.10 (7) with the pyrazole ring.
part of aromatic polymer chains. The pyrazole unit is one of the core structures in a number of natural products and has been attracted attention in the field of biology (Habeeb et al., 2001, Hashimoto et al. 2002. Extensive studies have been devoted to arylpyrazole derivatives such as celecoxib,a well-known cyclooxygenase-2 inhibitor (Ranatunge et al., 2004;Singh et al. 2005). Recently, pyrazole derivatives have been reported as high affinity and selective A2B adenosine receptor antagonist (Elzein et al., 2006). On the other hand, it was shown that aromatic polymer with diazole rings in the main chain exhibit high thermal resistance in oxidative atmosphere, good hydrolytic stability, low dielectric permittivity, high toughness and other special properties which are determined by the electronic structure of this particular heterocycle (Schulz et al., 1997;Sava et al., 2003). The incorporation of oxadiazole and imide rings together with flexible groups into the polymer chain is expected to provide a combination of high-performance properties and processability , Sava et al., 2006. The title compound, 2-(5-(2-(4-nitrophenoxy)phenyl)-1-phenyl-1H-pyrazol-3-yl)phenol has the prerequisite arylether linkages along with the hydroxyl and nitro-moieties and therefore can be an attractive synthon in material for biological application.
The o-phenol ring and the pyrazole ring in the title compound are almost coplanar [dihedral angle 0.95 (12)°] due to an intramolecular hydrogen bond, whereas the phenyl ring is tilted by 40.81 (7)° to the pyrazole ring. The aromatic ring carrying the nitrophenoxy substitutent makes a dihedral angle of 54.10 (7)° with the pyrazol ring. Crystal packing is determined by van der Waals interactions.

Experimental
A mixture of 0.961 g (0.0061 mol) of 4-nitrophenol, 2 g (0.0061 mol) of synthesized 2-(3-(2-hydroxyphenyl)-1-phenyl-1Hpyrazol-5-yl)phenol (Mukherjee, 2000) and 0.842 g (0.0061 mol) of potassium carbonate in 50 ml of DMF was heated with stirring at 393 K for 12 h. The reaction mixture was cooled to room temperature and poured into 800 ml of ice cold water which resulted the yellow precipitation. After being washed repeatedly with water, the product was collected by filtration and was recrystallized from DMF to yield 72% of product (m.p. 474 K).

Refinement
Hydrogen atoms bonded to C were included in calculated positions [C-H = 0.95 Å] and refined as riding [U iso (H) = 1.2U eq (C)]. The hydroxyl H atom was freely refined.
supplementary materials sup-2 Figures Fig. 1. A view of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. The intramolecular hydrogen bond is shown as a dashed line.

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 , convention-