Crystal structure and Hirshfeld surface analysis of 4-[4-(1H-benzo[d]imidazol-2-yl)phenoxy]phthalonitrile monohydrate

In the crystal, strong O—H⋯N hydrogen bonds link the molecules into supramolecular chains propagating along the c-axis direction.


Chemical context
Benzimidazole derivatives, as nitrogen-containing aromatic heterocyclic compounds, are a very important class owing to their biological importance (Preston, 2008). They are widely used as antiulcer, antifungal and antimycobacterial compounds (Patil et al., 2008) and have also attracted attention as organic fluorescent chromophores in recent years (Verdasco et al., 1995). Phthalonitrile derivatives are widely used precursors for the preparation of phthalocyanines, an important class of molecules not only as commercial pigments but also as important functional materials in many areas (Sharman et al., 2003). The preparation of phthalocyanines is carried out by cyclotetramerization reactions of phthalonitriles. The development of benzimidazole derivative-substituted phthalocyanines from the related phthalonitriles is crucial in terms of achieving a combination of functional groups.
We now report for the first time that benzimidazole groups linked directly through oxygen bridges to phthalonitrile units are new functionalized materials. We have described the synthesis, characterization and spectroscopic behavior of the synthesized starting phthalonitrile compound (Sen et al., 2018). ISSN 2056-9890

Figure 2
A partial view of the crystal packing. Dashed lines denote the intermolecular N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonding.

Figure 3
The Hirshfeld surface mapped over d norm .

Figure 1
The molecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 20% probability level.

Figure 4
Hirshfeld surfaces mapped over d norm to visualize the intermolecular interactions.
The overall two-dimensional fingerprint plot and those showing different contacts are characterized in Fig. 5, together with their relative contributions to the Hirshfeld surface. HÁ Á ÁH/HÁ Á ÁH interactions, contributing 28.7% to the overall crystal packing, are some of the important interactions, and are shown in Fig. 6 as an end point that points to the origin with the tips at d i = d e = 1.1 Å . The CÁ Á ÁH/HÁ Á ÁC contacts in the structure, with a 27.1% contribution to the Hirshfeld surface, have a symmetrical distribution of points, with the tips at d e + d i = 2.7 Å . The contribution from the NÁ Á ÁH/HÁ Á ÁN contacts, corresponding to C-HÁ Á ÁN and O-HÁ Á ÁN interactions, is represented by a pair of sharp spikes characteristic of a strong hydrogen-bond interaction (26.4%). The OÁ Á ÁH/ HÁ Á ÁO contacts, with a 3.7% contribution, appear with the points of low densities. Lastly, the CÁ Á ÁN/NÁ Á ÁC, CÁ Á ÁC/CÁ Á ÁC and OÁ Á ÁC/CÁ Á ÁO interactions in the structure with 6.1, 5.5 and 1.4% contributions, respectively, have symmetrical distributions of points.

Database survey
There are no direct precedents for the structure of the title compound in the crystallographic literature (Groom et al., 2016). However, there are several precedents for the 2-

Synthesis and crystallization
The synthesis of the title compound ( Fig. 7) was described by Sen et al. (2018). 4-[4-(1H-Benzo[d]imidazole-2yl)phenoxy]phthalonitrile, 4-nitrophthalonitrile (0.989 g, 5.71 mmol) and 2-(4-hydroxyphenyl)benzimidazole (1.2 g, 5.71 mmol) were dissolved in DMF (15 mL) under argon. After stirring for 15 min, anhydrous K 2 CO 3 (0.790 g, 5.71 mmol) was added portionwise over 2 h with efficient stirring. The suspension was maintained at 333 K for 24 h. The progress of the reaction was monitored by TLC using a CHCl 3 /EtOAc (10/1) solvent system. After the reaction was observed to be complete, the resulting mixture was poured into an ice-water mixture. The immediate precipitate was collected by filtration, washed with hot water, ethanol and diethyl ether and dried in vacuo. The desired pure compound was obtained in sufficient purity, yield: 96% (1.84 g). m.p. 421 K.

4-[4-(1H-Benzo[d]imidazol-2-yl)phenoxy]phthalonitrile monohydrate
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.