Crystal structure and Hirshfeld surface analysis of (2E)-3-(3-chlorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one

In the crystal, molecules are linked by C—H⋯O hydrogen contacts, enclosing an (14) ring motif, and by a further C—H⋯O hydrogen contact, forming a two-dimensional supramolecular structure extending along the direction parallel to the ac plane.


Chemical context
Materials exhibiting two photon absorption (TPA) have wide applications such as frequency-up lasing, multi-photon microscopy, three-dimensional fluorescence imaging, eye and sensor protection. Materials with potential non-linear optical (NLO) properties have significant applications in the field of photonics. Chalcone and its derivatives have attracted significant attention in the past few years because of their availability of high optical non-linearities resulting from the significant delocalization of -conjugated electron clouds throughout the chalcone system, providing a large chargetransfer axis with appropriate substituents on the terminal aromatic rings. The second harmonic generation (SHG) efficiency of these compounds is due to the strong intermolecular electron-donor-acceptor interactions, which may also enhance the non-linear optical (NLO) properties. With the possibility of developing low-cost, large-area and flexible electronic devices, -conjugated systems have been studied extensively for their optoelectronic properties (Chandra Shekhara Shetty et al., 2016, 2017.

Supramolecular features and Hirshfeld surface analysis
In the crystal, molecules are linked by C-HÁ Á ÁO hydrogen contacts (Table 1, Fig. 2), enclosing an R 2 2 (14) ring motif, and by a further C-HÁ Á ÁO hydrogen contact, forming a threedimensional structure extending in the a-and c-axis directions.
Hirshfeld surfaces and fingerprint plots were generated for the title compound based on the crystallographic information file (CIF) using CrystalExplorer (McKinnon et al., 2007).  The molecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 4
Hirshfeld surface of the title complex plotted over shape-index.   Table 2 Summary of short interatomic contacts (Å ) in the title compound.
senting short or long contacts and indicating the relative strength of the interactions. Figs. 3 and 4 show the Hirshfeld surfaces mapped over d norm (À0.16 to 1.25 a.u.) and shapeindex (À1.0 to 1.0 a.u.). In Fig. 3, the spots near atoms O2 and O3 result from the C15-H15AÁ Á ÁO2 ii and C11-H11AÁ Á ÁO3 i interactions significant in the molecule packing of the title compound ( Table 1). Some of the short intermolecular contacts for the title compound are listed in Table 2. The Hirshfeld surfaces illustrated in Fig. 3 also reflect the involvement of different atoms in the intermolecular interactions through the appearance of blue and red regions around the participating atoms, which correspond to positive and negative electrostatic potential, respectively.

Synthesis and crystallization
The reagents and solvents for the synthesis were obtained from the Aldrich Chemical Co. and were used without additional purification. 1-(3,4-Dimethoxyphenyl) ethanone (0.01 mol) and 3-chlorobenzaldehyde (0.01 mol) were dissolved in 20 ml methanol. A catalytic amount of NaOH was added to the solution dropwise with vigorous stirring. The reaction mixture was stirred for about 5-6 h at room temperature. The progress of the reaction was monitored by TLC. The formed crude products were filtered, washed successively with distilled water and recrystallized from ethanol to get the title chalcone. Crystals suitable for X-ray diffraction studies were obtained from acetone solution by slow evaporation at room temperature. The melting point (371-373 K) was determined by a Stuart Scientific (UK) apparatus. The purity of the compound was confirmed by thin layer chromatography using Merck silica gel 60 F254 coated aluminum plates.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > 2sigma(F 2 ) is used only for calculating -R-factor-obs 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.