Crystal structure and theoretical study of (2E)-1-[4-hydroxy-3-(morpholin-4-ylmethyl)phenyl]-3-(thiophen-2-yl)prop-2-en-1-one

The molecular conformation is stabilized by an intramolecular O—H⋯N hydrogen bond. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming wave-like layers. C—H⋯π interactions involving the benzene rings and the methylene hydrogen atoms of the morpholine rings are observed between the layers.

Mannich bases are an important class of compounds in medicinal chemistry. The Mannich reaction can be considered as a substitution reaction of a suitable compound in which one or more aminomethylation processes happen, depending on the nature of the reactants. The biological activities of Mannich bases may result from their chemical structures or from the production of ,-unsaturated ketone moieties (Roman, 2015). The title compound was designed with the expectation of observing an increased bioactivity or cytotoxicity in a molecule including both chalcone and Mannich base pharmakophores.

Supramolecular features
In the crystal, molecules are linked by intermolecular C-HÁ Á ÁO hydrogen bonds, forming wave-like layers parallel to the ab plane (Table 1, Fig. 2). C-HÁ Á Á interactions are observed between the benzene rings and the methylene hydrogen atoms of the morpholine rings in adjacent layers, forming a three-dimensional network.

Database survey
A search of the Cambridge Structural Database (Version 5.39, update May 2018;Groom et al., 2016) for the 2-(morpholinomethyl)phenol substructure yielded two hits, namely BOPMEY (Fun et al., 1999) and IHUBIW (Xie et al., 2003). In both compounds, the amine N atoms of the morpholine rings and the hydroxy groups of the phenol fragments are engaged in intramolecular hydrogen bonds.
In addition, the geometrical optimization calculations of the title compound were performed using the PM3 (Parameterized Model number 3) method (Stewart, 1989a,b) in WinMopac7.2. A view of the molecule calculated with PM3 is shown in Fig. 4 Table 1 Hydrogen-bond geometry (Å , ).

Figure 2
The molecular packing of the title compound viewed down the a axis. Hydrogen bonds are shown as dashed lines.

Figure 3
Spatial view of the title compound calculated using the CNDO method.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level Figure 4 Spatial view of the title compound calculated using the PM3 method À0.1724 and 0.0829 eV, respectively. These calculations were performed assuming the molecule to be isolated and in an absolute vacuum. A comparison between experimental and calculated bond lengths (r.m.s. deviations of 0.029 and 0.016 Å for CNDO and PM3, respectively) and angles (r.m.s. deviations of 1.601 and 1.915 for CNDO and PM3, respectively) is given in Table 2. The PM3 method gave the lowest values for HOMO, LUMO and dipole moments.

(2E)-1-[4-Hydroxy-3-(morpholin-4-ylmethyl)phenyl]-3-(thiophen-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.