(2E)-1-(4-Aminophenyl)-3-(2-thienyl)prop-2-en-1-one ethanol hemisolvate

In the title compound, C13H11NOS·0.5C2H6O, the chalcone derivative is close to planar, the dihedral angle between the thiophene and 4-aminophenyl rings being 3.1 (2)°. The thiophene ring is disordered over two orientations with occupancies of 0.842 (3) and 0.158 (3). In the crystal structure, molecules are linked into chains along the b axis by N—H⋯O hydrogen bonds. The chains are crosslinked via N—H⋯π interactions involving the thiophene ring. The ethanol solvent molecule is also disordered over two positions, each with an occupancy of 0.25.


Comment
Chalcones have been reported to be responsible for a variety of biological activities such as analgesic, anti-inflammatory, antibacterial and antimycotic properties (Dimmock et al., 1999;Go et al., 2005;Ni et al., 2004). Some of the synthetic chalcones have also been found to be non-linear optical (NLO) materials (Patil & Dharmaprakash, 2008). These interesting activities have led us to synthesize the title heteroaryl chalcone, (I), in order to study its NLO properties and biological activities. Herein we report the crystal strcuture of (I). The title compound crystallizes in orthorhombic noncentrosymmetric space group P2 1 2 1 2 1 and therefore it is expected to exhibit second-order non-linear optic properties.
The molecule of the title heteroaryl chalcone ( In the crystal, molecules are linked into chains along the b axis through N-H···O hydrogen bonds ( Fig. 2 and Table 1).

Experimental
The title compound was synthesized by the condensation of 4-aminoacetophenone (0.40 g, 3 mmol) with thiophene-2-carboxaldehyde (0.28 ml, 3 mmol) in ethanol (30 ml) in the presence of 10% NaOH (aq) (5 ml). After stirring for 2 hr at room temperature, the resulting yellow solid was collected by filtration, washed with distilled water, dried and purified by repeated recrystallization from acetone. Yellow plate-shaped single crystals of the title compound suitable for X-ray structure determination were grown by slow evaporation of an ethanol solution at room temperature after several days, (m.p. 378-379 K).

Refinement
The thiophene ring of the chalcone is disordered over two orientations with occupancies of 0.842 (3) and 0.158 (3). The same anisotropic displacement parameters were used for atoms pairs C12A/C11, C11A/C12 and C13A/C13. Atoms S1A, C11A, C12A, C13A and C10 were restrained to be coplanar. The ethanol solvent molecule is also disordered over two positions across a center of symmetry. Their occupanicies were initially refined to 0.248 (5) and 0.242 (5) and later both were fixed at 0.25. Both disorder components were refined isotropically. The C-O, C-C and O···C distances were restrained to 1.42 (1), 1.51 (1) and 2.43 (1) Å, respectively. All H atoms were placed in calculated positions, with N-H = 0.86 Å, C-H = 0.93-0.97 Å. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl and hydroxyl H atoms and 1.2U eq (C) for the remaining H atoms. A rotating group model was used for the methyl groups. The highest residual electron density peak is located at 0.96 Å from H2B and the deepest hole is located at 0.30 Å from H14B. The final difference density features indicate that the solvent molecule may be disordered over multiple sites.
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 > σ(F 2 ) is used only for calculating Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (