(2E)-3-(4-Methylphenyl)-1-(3-nitrophenyl)prop-2-en-1-one

The title compound, C16H13NO3, crystallizes with two independent molecules (A and B) in the asymmetric unit. The dihedral angle between the mean planes of the 4-methylphenyl and 3-nitrophenyl groups is 4.0 (3)° in molecule A and 16.2 (7)° in molecule B. Intermolecular C—H⋯O hydrogen bonding involving the O atoms of the 3-nitrophenyl group of both independent molecules link the molecules into layers approximately parallel to the (110) plane. The layers are held together by π–π stacking interactions between the 4-methylphenyl ring of molecule A and the 3-nitrophenyl ring of molecule B of the adjacent layer, with the distance between the centroids of interacting rings being 3.6987 (7) Å.

The title compound, C 16 H 13 NO 3 , crystallizes with two independent molecules (A and B) in the asymmetric unit. The dihedral angle between the mean planes of the 4methylphenyl and 3-nitrophenyl groups is 4.0 (3) in molecule A and 16.2 (7) in molecule B. Intermolecular C-HÁ Á ÁO hydrogen bonding involving the O atoms of the 3-nitrophenyl group of both independent molecules link the molecules into layers approximately parallel to the (110) plane. The layers are held together bystacking interactions between the 4methylphenyl ring of molecule A and the 3-nitrophenyl ring of molecule B of the adjacent layer, with the distance between the centroids of interacting rings being 3.6987 (7) Å .
KL thanks Mangalore University for use of their research facilities. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase the X-ray diffractometer.

S1. Comment
Chalcones can be easily obtained from the Claisen-Schmidt reaction of aromatic aldehydes and aromatic ketones.
The title compound crystallizes with two independent molecules (A and B) in the asymmetric unit (Fig. 1). The dihedral angle between the mean planes of the 4-methylphenyl and 3-nitrophenyl groups is 4.0 (3)° in molecule A and 16.2 (7)° in molecule B. Crystal packing is stabilized by intermolecular C-H···O hydrogen bonding involving the O atoms on the 3nitrophenyl group of both indpendent molecules. These hydrogen bonds (Table 1) link the molecules into a layer approximately parallel to the (1 1 0) plane (Fig. 2). Intermolecular π-π stacking interactions occur between 4-methylphenyl ring of molecule A at (x, y, z) and 3-nitrophenyl ring of molecule B of the adjacent layer at (1 -x, 1 -y, -z), with the distance between the centroids of interacting rings being 3.6987 (7) Å.

S2. Experimental
A solution of 1-(3-nitrophenyl)ethanone (1.65 g, 0.01 mol) and 4-methylbenzaldehyde (1.20 g, 0.01 mol) in ethanol (25 ml) was stirred well and 10% NaOH solution (5 ml) was added. The reaction mixture was stirred for about 6 h and filtered. The product was crystallized from acetone (m.p. 414-416 K). Single crystals suitable for X-ray structure determination were grown by slow evaporation of an acetone solution of the title compound at room temperature.

S3. Refinement
All H atoms were placed in calculated positions (C-H = 0.93 or 0.96 Å) and refined using a riding model, with U iso (H) = 1.16-1.21U eq (C).  The asymmetric unit of the title compound, showing atom labeling. Displacement ellipsoids are drawn at the 50% probability level. 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 R-factors based on ALL data will be even larger.