Crystal structure and Hirshfeld surface analysis of (E)-1-(3,5-dichloro-2-hydroxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one

The title chalcone derivative is almost planar, with a dihedral angle of 7.0 (2)° between the 3,5-dichloro-2-hydroxyphenyl and 5-methylfuran rings.


Chemical context
Chalcone derivatives are an important class of organic compounds comprising two aromatic rings connected via an , unsaturated carbonyl system. They belong to the flavonoid family, which are basically found in fruits and vegetables (Hijova 2006). Chalcones occupy an important place in the pharmaceutical industry since their derivatives serve as the core structures for many organic compounds possessing various biological activities such as antibacterial (Vibhute & Baseer, 2003), anti-microbial (Prasad et al., 2006), antiinflammatory (Lee et al., 2006), anti-hyperglycemic (Satyanarayana et al., 2004), anti-malarial (Syahri et al., 2017) and anti-oxidant (Cheng et al., 2008). Chalcones also exhibit some non-linear optical (NLO) properties and also find applications in laser technologies such as optical communications, data storage and signal processing because of the , unsaturated functionality (Shobha et al., 2017). Based on the above importance, we report here the crystal structure of (E)-1-(3,5dichloro-2-hydroxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one.

Figure 1
The molecular structure of the title compound, with atom labelling and 50% probability displacement ellipsoids. The intramolecular hydrogen bond (Table 1) is indicated by a dashed line.

Figure 3
A view along the b axis of the crystal packing of the title compound. The hydrogen bonds (Table 1) and short contacts (Table 2) in the crystal structure are shown as dashed lines. spherical atomic electron densities and are obtained using the CrystalExplorer software (Spackman & Jayatilaka 2009).
The three-dimensional Hirshfeld surface was mapped over d norm using a red-blue-white colour scheme where the red and blue regions indicate contact distances less then and greater than, respectively, the sums of the van der Waals radii, which have negative and positive d norm values, respectively. In white regions where d norm is zero the contacts are almost equal to the sum of the van der Waals radii (Shaik et al. 2017). The presence of an intermolecular C-HÁ Á ÁO interaction is indicated by a deep-red circular spot on the d norm surface (Fig. 4). In addition, intermolecular C-HÁ Á ÁO interactions can also be viewed on the Hirshfeld surface mapped over electrostatic potential using a STO-3G basis set at the HF (Hartree-Fock) level of theory (Spackman & McKinnon 2002;McKinnon et al. 2004) as shown in Fig. 5. The donor and acceptor atoms participating in these interactions are shown respectively as positive (blue regions) and negative electrostatic potentials (red regions).
The two-dimensional fingerprint (Fig. 6) plots were generated in the expanded mode for all major intermolecular interactions giving their percentage of contribution towards packing of total Hirshfeld surface area for the molecule. The HÁ Á ÁCl interactions make the highest (26.1%) contribution to the total Hirshfeld surface and appear as a pair of wings in the region 1.2 Å < (d e + d i ) < 1.8 Å (d i is the distance of a point on the Hirshfeld surface to the nearest nucleus inside the surface while d e is the distance of the nearest nucleus outside the surface). The HÁ Á ÁH contacts, with a contribution of 25.7%, are shown as blue dots spread in the middle region 1.18 Å < (d e + d i ) < 1.62 Å . The two sharp spikes observed at 1.04 Å < (d e + d i ) < 1.39 Å are due to the presence of a pair of OÁ Á ÁH contacts making a 15.2% contribution. A pair of CÁ Á ÁH contacts are observed as characteristic wings in the region of 1.18 Å < (d e + d i ) < 1.6 Å (13.0% contribution). CÁ Á ÁC, CÁ Á ÁCl and OÁ Á ÁC contacts make contributions of 7.9%, 5.2% and 3.8%, respectively.

Synthesis and crystallization
1-(3,5-Dichloro-2-hydroxyphenyl)-2-hydroxyethanone (5 mmol) was dissolved in methanol (15 ml) and was stirred with 5 ml of sodium hydroxide solution for 30 min at room temperature. To this mixture, 5-methylfuran-2-carbaldehyde (5 mmol) was added over 30 min with stirring. Stirring at room temperature was then continued for 32 h. On completion of the reaction, monitored by TLC, the mixture was quenched in ice-water and acidified with dilute hydrochloric acid. The separated precipitate of the title compound was filtered off The Hirshfeld surface mapped over d norm in the range À0.1183 to +1.0844 a.u. The circular red spots indicate intermolecular C-HÁ Á ÁO interactions.

Figure 5
The Hirshfeld surface mapped over electrostatic potential in the range À0.0506 to +0.0422 a.u. The donor and acceptor atoms participating in these interactions are shown respectively as positive (blue regions) and negative electrostatic potentials (red regions).

Figure 6
Two-dimensional fingerprints plots. and recrystallized from methanol solution giving colourless block-like crystals.

(E)-1-(3,5-Dichloro-2-hydroxyphenyl)-3-(5-methylfuran-\ 2-yl)prop-2-en-1-one
Crystal data Special details 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.