(E)-1-(2-Aminophenyl)-3-(thiophen-2-yl)prop-2-en-1-one

The molecule of the title heteroaryl chalcone derivative, C13H11NOS, exists in a trans-configuaration and is almost planar with a dihedral angle of 3.73 (8)° between the phenyl and thiophene rings. An intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, two adjacent molecules are linked into a dimer in an anti-parallel face-to-face manner by a pair of C—H⋯O interactions. Neighboring dimers are further linked into chains along the c-axis direction by N—H⋯N hydrogen bonds.

The molecule of the title heteroaryl chalcone derivative, C 13 H 11 NOS, exists in a trans-configuaration and is almost planar with a dihedral angle of 3.73 (8) between the phenyl and thiophene rings. An intramolecular N-HÁ Á ÁO hydrogen bond generates an S(6) ring motif. In the crystal, two adjacent molecules are linked into a dimer in an anti-parallel face-toface manner by a pair of C-HÁ Á ÁO interactions. Neighboring dimers are further linked into chains along the c-axis direction by N-HÁ Á ÁN hydrogen bonds.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PLATON (Spek, 2009), Mercury (Macrae et al., 2006) and publCIF (Westrip, 2010  The basic structure of chalcones consists of two aromatic rings bound by an α,β-unsaturated carbonyl group, a unique template associated with various biological activities such as analgesic, anti-inflammatory, antibacterial (Go et al., 2005;Liu et al., 2008;Ni et al., 2004), anticancer and antioxidant (Shenvi et al., 2013) as well as tyrosinase inhibitory (Nerya et al., 2004) and fluorescence  properties. The title compound (I) was synthesized and studied for antioxidant activity by the DPPH scavenging method (Molyneux, 2004). Our result showed that (I) exhibits a weakly antioxidant activity. It was also tested for antityrosinase activity but found to be inactive. Herein we report the crystal structure of (I).
In the crystal packing (Fig. 3), two adjacent molecules are linked in an anti-parallel face-to-face manner into a dimer by a pair of C thiophene -H···O interactions and the neighboring dimers are further linked into chains along the c axis by N-H···N hydrogen bonds ( Fig. 4 and Table 1).

Experimental
The title compound (I) was prepared by mixing 2-aminoacetophenone (0.40 g, 3 mmol) and 2-thiophenecarboxaldehyde (0.34 g, 3 mmol) in ethanol (30 ml). 30% NaOH aqueous solution (5 ml) was then added and the mixture was stirred at room temperature for 2 hr. The yellow solid formed was filtered and washed with distilled water. Yellow block-shaped single crystals of (I) suitable for x-ray structure determination were recrystallized from ethanol by slow evaporation at room temperature over a few weeks. M.p. 407-408 K.

Refinement
Amino H atoms were located in difference maps and refined isotropically. The remaining H atoms were fixed geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic and 0.98 for CH. The U iso values were constrained to be 1.2U eq of the carrier atoms. Four outliers (1 5 4, 5 5 2, -1 5 5, -33 3 15) were omitted from supplementary materials sup-2 Acta Cryst. (2013). E69, o1004-o1005 the last refinement cycles.

Figure 1
The asymmetric unit of the title compound showing 50% probability displacement ellipsoid. Intramolecular N-H···O hydrogen bond is drawn as dashed line.

Figure 2
The molecular structure of the title compound showing the approximate planarity of the molecule and the interplanar angle between phenyl and thophene rings.  The crystal packing of the title compound viewed along the b axis. Hydrogen bonds are drawn as dashed lines.

Figure 4
The crystal packing of the title compound, showing a chain of dimers running along the c axis. Hydrogen bonds are drawn as dashed lines. 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 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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 0.071728 (