Crystal structure of 1-[2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazol-1-yl]propan-2-ol

The molecular and crystal structure of the title imidazole derivative is reported. The structure features an extensive O—H⋯N, C—H⋯O/N and C—H⋯π(ring) hydrogen-bonding network.


Chemical context
Imidazole compounds form the core of the structures of some well-known components of human organisms including the amino acid histidine, vitamin-B12, a component of the DNA base structure and the purines, histamine and biotin. It is also present in the structure of many natural or synthetic drug molecules, for example cimetidine, azomycin and metronidazole (Kleeman et al., 1999). Imidazole derivatives display an extensive range of biological activities and are thus used as antibacterial (Vijesh et al., 2011;Lu, et al., 2012), anticancer (Yang et al., 2012;Alkahtani et al., 2012), anti-tubercular (Lu, et al., 2012;Lee et al., 2011), analgesic (Kankala et al., 2013;Gaba et al., 2010) and anti-HIV agents (Zhan et al., 2009). As part of an ongoing study of the synthesis of imidazole-based amino aliphatic alcohols, e.g. amino ethanol and amino isopropanol Mohamed et al., 2013a,b;Jasinski et al., 2015), we report here the synthesis and crystal structure of the title compound.

Structural commentary
The title compound, (I), crystallizes with two unique molecules, 1 and 2, in the asymmetric unit. In the numbering scheme these molecules are differentiated by leading 1 and 2 digits, respectively, Fig. 1.
The unique molecules form dimers in the asymmetric unit through O212-H210Á Á ÁN13 and C253-H253Á Á ÁO13 hydrogen bonds that enclose R 2 2 (18) rings, Fig. 1. The two also similar and compare well with those found in comparable molecules with isopropanol substituents at the 1-position Mohamed et al., 2017;Akkurt et al., 2015).

Figure 1
The asymmetric unit of (I), with displacement ellipsoids drawn at the 50% probability level. Hydrogen bonds between the two unique molecules are shown as yellow dashed lines.

Database survey
The Cambridge Structural Database (Version 5.38 with three updates; Groom et al., 2016) shows that molecules with the lophine skeleton and a CH 2 substituent on N1 are reasonably common with 43 entries. However, restricting the search to compounds with isopropanol substituents on N1 reduces the hits to three reports of our work to produce compounds with 4-benzoic acid  and 4-chloro-  and 2,5-dichloro-substituents  at the 2-position of the imidazole ring. A more recent paper, detailing the use of ionic liquids as catalysts for the preparations of similar compounds, also reports analogues with an unsubstituted phenyl ring and a 2,5-dimethoxy substituted benzene ring at the 2-positions . Other closely related derivatives have ethanol (Mohamed et al., 2013a) and n-propanol substituents on the N1 atom .

Synthesis and crystallization
The title compound was prepared according to our previously reported method . Crystals suitable for X-ray analysis were obtained by the slow evaporation method using ethanol as a solvent. M.p. 451-453 K, yield, 87%.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The hydrogen atoms of the OH groups on O112 and O212 were located in a difference-Fourier map and their coordinates refined with U iso = 1.5U eq (O). All other atoms were refined using a riding model with d(C-H) = 0.95 Å for aromatic, 1.00 Å for methine and 0.98 Å for CH 2 atoms, all with U iso (H) = 1.2U eq (C). For methyl H atoms d(C-H) = 0.98 Å and U iso (H) = 1.5U eq (C). One low angle reflection with F o << F c that may have been affected by the beamstop was omitted from the final refinement cycles. Chains of molecules of (I) along c. C-HÁ Á Á(ring) contacts are drawn as dotted green lines with ring centroids shown as coloured spheres.

Figure 5
Chains of type 2 molecules of (I) along a linked to type 2 molecules, forming sheets in the ac plane.

Figure 6
Overall packing of (I) viewed along the a-axis direction.     (Hunter & Simpson, 1999); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b), enCIFer (Allen et al., 2004), PLATON (Spek, 2009), publCIF (Westrip, 2010) and WinGX (Farrugia, 2012). 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. Refinement. One low angle reflection with Fo <<< Fc that may have been affected by the beamstop was omitted from the final refinement cycles.