Crystal structure and Hirshfeld surface analysis of 4-(naphthalen-2-yl)-N-[(Z)-4-propoxybenzylidene]-1,3-thiazol-2-amine

In the crystal, the molecules are linked by weak C—H⋯π hydrogen bonds and very weak π–π stacking interactions. Two-dimensional fingerprint plots show that the largest contributions to the crystal cohesion come from H⋯H and C⋯H/H⋯C interactions.


Chemical context
is a compound having the general formula RN CR 2 (R = H, hydrocarbyl) and thus belongs to the family of imines (McNaught & Wilkinson, 1997). The chemistry of Schiff bases and their derivatives has been an interesting field of research since their discovery. Subsequently, Schiff bases have constituted a significant class of compounds for new drug development, exhibiting biological activities including antimicrobial, anti-tuberculosis, antioxidant, anti-inflammatory, anticonvulsant, antidepressant, anxiolytic, antihypertensive, anticancer and antifungal properties. The search for Schiff base-containing compounds with more selective activity and lower side effects continues to be an active area in medicinal chemistry (Kumar et al., 2017). Likewise, heterocyclic compounds play an essential role in medicinal chemistry, or as key templates for the development of various therapeutic agents. As part of this family, thiazoles (Ghawla Amit et al., 2014) and their derivatives have been found to possess anticonvulsant, antimicrobial, anti-inflammatory, anticancer, anti-HIV, antidiabetic, anti-Alzheimer, antihypertensive, and antioxidant activities. As a result of their potent and significant biological activities, they have excellent pharmaceutical importance (Kaur & Goyal, 2018).
Here we report on the synthesis, structure determination and Hirshfeld analysis of a Schiff base, C 23 H 20 N 2 OS, (I), comprising a thiazole entity.

Structural commentary
The asymmetric unit of (I) contains one molecule (Fig. 1). The molecule is slightly bent, with the naphthalene ring system and the thiazole ring inclined to each other, subtending a dihedral angle of 13.69 (10) ; the anisole moiety is inclined to the plane of the naphthalene ring system, the dihedral angle being 14.22 (12) . The C18-O1 and C21-O1 bond lengths are typical of single bonds (Table 1). The bond-length distribution in the thiazole ring is normal. The C11-N1 bond has singlebond character and the C13-N1 bond double-bond character, with bond lengths of 1.380 (3) and 1.304 (3) Å , respectively.

Figure 2
A view of the crystal packing of the title compound in a view along the b axis. C-HÁ Á Á(ring) interactions are indicated by dashed lines.  The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 40% probability level.
(high) surface resolution with the three-dimensional d norm surfaces mapped over a fixed colour scale of À0.0638 (red) to 1.3242 (blue) a.u., and the results are illustrated in Fig. 4a. The red spots identified in Fig. 4a correspond to the near-type HÁ Á Á contacts resulting from hydrogen bonds of the type C-HÁ Á Á(ring) ( Table 2). The view of the three-dimensional Hirshfeld surface of the title compound plotted over electrostatic potentials with a fixed colour scale of À0.049 (red) to 0.034 (blue) a.u. is given in Fig. 4b, emphasizing on C-HÁ Á Á(ring) contacts. Fig. 5a shows the two-dimensional fingerprint as the sum of all contacts contributing to the Hirshfeld surface indicated in normal mode. Fig. 5b illustrates the two-dimensional fingerprint of (d i , d e ) points related to HÁ Á ÁH contacts that represent a 42.5% contribution in the title structure. In Fig. 5c, two symmetrical wings on the left and right sides indicate CÁ Á ÁH/ HÁ Á ÁC interactions with a contribution of 37.2%. Furthermore, there are SÁ Á ÁH/HÁ Á ÁS (8.2%; Fig. 5d), NÁ Á ÁH/HÁ Á ÁN (7.5%; Fig. 5e) and OÁ Á ÁH/HÁ Á ÁO (2.2%; Fig. 5f) contacts contributing to the overall crystal packing of (I).      bath at approximately 278-283 K. The reaction was monitored by thin-layer chromatography (TLC) using ethyl acetate and n-hexane (3:7 v:v), and had an R f of 0.675. The formed precipitate was filtered off, washed with 1-propanol, and dried. The resulting solid was further purified by washing with ethanol and diethyl ether. Single crystals of (I) for X-ray analysis were obtained by slow evaporation of an acetone solution (yield 60%, m.p. 411-413 K).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The C-bound H atoms were placed in idealized positions and refined using a riding model with C-H = 0.93-0.97 Å and U iso (H) = 1.5U eq (C-methyl) or 1.2U eq (C) for other C-bound H atoms.

sup-2
Acta Cryst. (2020). E76, 920-923 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.