Crystal structure and Hirshfeld surface analysis of 3-({4-[(4-cyanophenoxy)carbonyl]phenoxy}carbonyl)phenyl 4-(benzyloxy)-3-chlorobenzoate

The title compound is a non-liquid crystal with a bent-shaped molecule in which adjacent aromatic rings are close to perpendicular to each other.


Chemical context
Banana/bent-shaped liquid crystals (LCs) are of great interest in the field of display materials. In particular, the -CN groups at the terminal end (Walba et al., 2000;Reddy & Sadashiva, 2004) of banana-shaped LCs have been linked to their bent or bow (twisted) anisometric phase with C 2v symmetry. Furthermore, they exhibit polar order, chirality and spontaneous polarization in the fluid phase. We have reported the crystal structures of LC intermediates and found that benzyloxy group-substituted molecules are prone to be hydrophobic (Kashi et al., 2012;Al-Eryani et al., 2011). Benzyloxy groupsubstituted molecules also play a significant role in synthesizing bent-shaped LCs and non-LCs (Palakshamurthy et al., 2012). Hence, it is useful to study benzyloxy group-substituted bent-shaped molecules to understand the structural properties and the relationship between LCs and crystal structures.
In a continuation of this work, we investigated the title molecule, which possesses five aromatic rings with three ester groups and a benzyloxy group at one terminal end, presumably making the molecule highly polar. Furthermore, it has a chloro group at one side and a cyano group at the opposite terminal end of the molecule, inducing an unsymmetrical structure (Hartung et al., 2000). The molecule was subjected to LC characterization studies, but it did not show any LC properties, which may be due to the absence of a flexible alkyl chain. The title compound was synthesized according to the procedure described by Sadashiva et al. (2002) and its crystal structure is reported herein.

Database survey
A search of the Cambridge Structural Database (CSD, version 5.42, update of November 2020;Groom et al., 2016) for molecules containing the (4-cyanophenoxy)carbonyl fragment resulted in four matches with CSD refcodes EWUSIA (Srinivasa et al., 2015), IBUXOV (Ji et al., 2017), IBUXUB (Yingchun et al., 2016) and OCUTIS (Yingchun et al., 2016). In all these structures there is a 4-cyanophenoxy grouping at the one end of the molecule, similar to the title compound. In IBUXOV, IBUXUB and OCUTIS the same core exists at both ends of the molecule. Sometimes the presence of a -CN group at both terminals of the molecule induces liquid-crystal properties.

Figure 2
The molecular packing of the title compound. Dashed lines indicate the C-HÁ Á Á interactions.

Figure 3
The molecular packing of the title compound. Dashed lines indicate the stacking interactions.
The Hirshfeld surface mapped over d norm is illustrated in Fig. 4 and the associated two-dimensional fingerprint plots in Fig. 5. The major contributions to the crystal structure are from HÁ Á ÁH (26.9%), CÁ Á ÁH (27.2%) and OÁ Á ÁH (19.6%) contacts. In Figs. 6 and 7, the red spots on the d norm and d e surfaces represent the C-HÁ Á Á interactions.

Figure 5
Two-dimensional fingerprint plots for the title compound.

Figure 6
Hirshfeld surface of the title compound mapped over d norm , showing the C-HÁ Á ÁN interactions.

Figure 7
Hirshfeld surface of the title compound mapped over shape-index, showing the C-HÁ Á Á interactions.
(10 ml) and 5% ice-cold sodium hydroxide solution (10 ml) and finally washed with water and dried over anhydrous sodium sulfate. The crude residue obtained was chromatographed on silica gel using chloroform as an eluent. Removal of solvent from the eluate afforded the white target material, which was crystallized from a mixture of chloroform and acetonitrile. Single crystals in the form of colourless prisms suitable for diffraction studies were grown from a solution in ethyl alcohol by slow evaporation.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Atoms H2, H4 and H6 were fully refined. Other H atoms were positioned with idealized geometry and refined using a riding model with C-H = 0.93-0.97 Å and U iso (H) = 1.2-1.5U eq (C).

Funding information
The authors thank the Vision Group on Science and Technology, Government of Karnataka, for the award of a major project under the CISEE scheme (   program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: SHELXL (Sheldrick, 2015b).

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.