Functionalized 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(4-substituted-phenyl)prop-2-en-1-ones: synthetic pathway, and the structures of six examples

Two series of functionalized chalcones have been synthesized from a common family of precursors, and the structures of three examples from each series have been determined. The supramolecular assembly, based upon C—H⋯O and C—H⋯π(arene) hydrogen bonds, is different in all of the examples examined.


Figure 2
The molecular structure of compound (Ic) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 3
The molecular structure of compound (Ie) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 4
The molecular structure of compound (IIa) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 5
The molecular structure of compound (IId) showing the atom-labelling scheme, and the disorder in the 2,4-dichlorophenyl group. The major disorder component is drawn using full lines and the minor disorder component is drawn using broken lines. Displacement ellipsoids are drawn at the 30% probability level.
Thus, the supramolecular assembly in the isomeric pair of compounds (Ib) and (Ic) is different in terms of the hydrogen bonds involved (Table 2), although chains of rings, different in Part of the crystal structure of compound (Ic) showing the formation of a chain of rings parallel to [110]. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted.

Figure 9
Part of the crystal structure of compound (Ie) showing the formation of a chain of rings parallel to [110]. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted. each case, are found in all three of the type (I) compounds. Amongst the type (II) compounds, (IIa) and (IId) exhibit either no direction-specific intermolecular interactions, as in (IIa), or finite, zero-dimensional aggregation, as in (IId). In (IIe), a chain of rings is again found, but different from those in any of the type (I) series, although the R 2 2 (20) motif can be identified in each of (Ib), (IId) and (IIe).

Figure 11
Part of the crystal structure of compound (IIe) showing the formation of a chain of rings parallel to [100]. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted. yl)-1-thiophen-2-yl)prop-2-en-1-ones, both of which exhibit disorder in the orientation of the thiophene unit (Shaibah et al., 2020).

Synthesis and crystallization
For the preparation of the prop-2-yn-1-yl compounds (I), a solution of potassium hydroxide (0.31g, 5.7 mmol) in ethanol

Refinement
Crystal data, data collection and refinement details are summarized in Table 3. For a number of the structures, [(Ie), (IIa), (IId) and (IIe)], the diffraction data at values of > 25 were uniformly of very indifferent quality, particular in terms of the symmetry-equivalent reflections. This is probably a consequence of the indifferent crystal quality, exemplifying the general difficulty within the series (I) and (II) of growing crystals suitable for single-crystal X-ray diffraction (cf. Section 5, above). These higher-angle reflections were therefore rejected during the data-reduction process: we note also that the intensity statistics indicated that very few of these reflections were likely to be labelled as observed for compounds (Ie), (IIa), (IId) and (IIe). A number of low-angle reflections for (Ib) and (Ie) were also discarded at this stage because of attenuation by the beam stop. Some further low-angle reflections that had been attenuated by the beam stop were omitted from the data sets before the final refinements, thus: for (Ib) (101), (110), (002), (202) and (202); for (Ic) (110) and (002); for (Ie) (002), (111) and (012); for (IIa) (111); and for (IId) (112). In addition, the bad outlier reflections (204) for (Id) and (130) for (IIe) were also omitted. All H atoms were located in difference maps and then treated as riding atoms in geometrically idealized positions with C-H distances 0.93 Å (aromatic), 0.96 Å (CH 3 ) or 0.97 Å (CH 2 ), and with U iso (H) = kU eq (C), where k = 1.5 for the methyl groups which were permitted to rotate but not to tilt, and 1.2 for all other H atoms. The final difference map for compound (Ie) contained two significant peaks, 0.85 e Å À3 at (0.227, 0.557, 0.598), and 0.81 e Å À3 at (0.380, 0.488, 0.596), respectively 1.27 and 1.14 Å from atom C351: however, attempts to develop a plausible disorder model based upon these two peaks were not fruitful.

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.

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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )