1-Phenyl-3-(pyren-1-yl)prop-2-en-1-one

The title compound, C25H16O, was prepared by the condensation reaction of pyrene-1-carbaldehyde and acetophenone in ethanol solution at room temperature. The phenyl ring forms a dihedral angle of 39.10 (11)° with the pyrene ring system. In the crystal structure, adjacent pyrene ring systems are linked by aromatic π–π stacking interactions, with a perpendicular interplanar distance of 3.267 (6) Å and a centroid–centroid offset of 2.946 (7) Å.

The title compound, C 25 H 16 O, was prepared by the condensation reaction of pyrene-1-carbaldehyde and acetophenone in ethanol solution at room temperature. The phenyl ring forms a dihedral angle of 39.10 (11) with the pyrene ring system. In the crystal structure, adjacent pyrene ring systems are linked by aromaticstacking interactions, with a perpendicular interplanar distance of 3.267 (6) Å and a centroid-centroid offset of 2.946 (7) Å .   (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1990); software used to prepare material for publication: SHELXTL.

Comment
Chalcone derivatives have always been of interest in the field of inorganic, organic and physical chemists and biology (Strack, 1997) due to their importance in many organic synthetic pathways, biochemical processes and enzymatic mechanisms (Ansari et al., 2005;Pattanaik et al., 2002;Nielsen et al., 2005). In this paper, we report the crystal structure of the title compound, which was obtained by the condensation reaction of pyrene-1-carbaldehyde and acetophenone in ethanol solution at room temperature.
In the title compound, the pyrene ring is substantially planar (maximum displacement 0.011 (4) Å for C12) and forms a dihedral angle of 39.10 (11)° with the phenyl ring. In the crystal packing, adjacent pyrene rings are linked by aromatic π-π stacking interactions, with a centroid-centroid distance of 4.339 (7) Å, a perpendicular interplanar distance of 3.267 (6) Å and a centroid-centroid offset of 2.946 (7) Å.

Experimental
The title compound was prepared by the condensation reaction of pyrene-1-carbaldehyde (0.05 mol) and acetophenone (0.05 mol) in ethanol (20 ml) at room temperature. Single crystals of the title compound suitable for X-ray measurements were obtained by slow evaporation of an ethanol/acetonitrile solution (1:1 v/v) at room temperature.

Refinement
All H atoms were fixed geometrically and were treated as riding on the parent C atoms, with C-H distances of 0.93 Å.
U iso (H) = 1.2 U eq (C). In the absence of significant anomalous scattering effects, Friedel pairs were merged in the final refinement. Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids and the atom-numbering scheme.

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 > 2sigma(F 2 ) is used only for calculat-supplementary materials sup-3 ing 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.