Crystal structure of 3-(9H-carbazol-9-yl)-N′-[(E)-4-chlorobenzylidene]propanohydrazide

In the title compound, C22H18ClN3O, the carbazole ring system is essentially planar (r.m.s deviation = 0.003 Å), and makes a dihedral angle of 9.01 (8)° with the plane of the chlorophenyl ring. In the crystal, neighbouring molecules are linked into centrosymmetric R 2 2(8) dimers by pairs of N—H⋯O interactions and into a three-dimensional network by C—H⋯π interactions. The dimers are arranged into layers parallel to (010).


S1. Comment
Carbazole scaffold compunds are well known for their pharmacological activities. The syntheses of carbazole derivatives in connection with the search for newer physiologically activities have been recognized in many reports (Hewlins et al., 1984;Kansal & Potier 1986;Haider et al., 1998;Hirata et al., 1999). Carbazomycin A and carbazomycin B have been found to be useful antibacterial and antifungal agents (Chowdhury et al., 1978;Sakano et al., 1980). In addition pyridocarbazoles show marked anticancer and anti-HIV activities (Pindur, 1990;Knölker & Reddy, 2002;Martin & Prasad 2006;Saturnino et al., 2003). Based on such facts we report in this study the synthesis and crystal structure of the title compound.
As shown in Fig. 1, the carbazole ring system (N1/C1-C12) of the title compound is essentially planar (r.m.s deviation = 0.003 Å), and makes a dihedral angle of 9.01 (8)° with the plane of the chlorophenyl ring (C17-C22). The bond lengths and angles are within normal ranges and are similar to those reported earlier for similar compounds.
In the crystal, two molecules are associated through a pair of N-H···O intermolecular hydrogen bonds, forming a centrosymmetric dimer with R 2 2 (8) ring motifs (Table 1), into layers parallel to (010) (Fig. 2). The dimers are connected by C-H···π interactions, forming a three-dimensional network.

S2. Experimental
A mixture of 1.5 mmol (380 mg) of 3-(9H-carbazol-9-yl)propanehydrazide and 1.5 mmol (261 mg) of 4-chlorobenzaldehyde was heated in 10 ml of absolute ethanol and 3 ml of acetic acid catalyst. The reaction was monitored by TLC till completion after 3 h. The product which deposited on cooling, was collected, dried under vacuum and recrystallized from dioxan to give orange plates in 78% yield.

S3. Refinement
All H atoms were placed in calculated positions with N-H = 0.81 and C-H = 0.93 -0.97 Å, and refined as riding with

Figure 1
View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.

Figure 2
View of the dimers formed by N-H···O hydrogen bonds down the b axis.

sup-3
Acta Cryst. (2015). E71, o937-o938  Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.