supplementary materials

Carbazole and its derivatives have become quite attractive compounds owing to their applications in pharmacy and molecular electronics. It has been reported that carbazole derivatives possess various biological activities, such as antitumor (Itoigawa et al., 2000), antioxidative (Tachibana et al., 2001), anti-inflammatory and antimutagenic (Ramsewak et al., 1999). Carbazole derivatives also exhibit electroactivity and luminescence properties and are considered to be potential candidates for electronic such as colour displays, organic semiconductor lasers and solar cells (Friend et al., 1999). These compounds are thermally and photochemically stable, which makes them useful materials for technological applications. For instance, the carbazole ring is easily funtionalized and covalently linked to other molecules (Diaz et al., 2002). This enables its use as a convenient building block for the design and synthesis of molecular glasses, which are widely studied as components of electroactive and photoactive materials (Zhang et al., 2004).

Against this background, and in order to obtain detailed information on molecular conformations in the solid state, X-ray studies of the title compounds (I) have been carried out. X-Ray analysis confirms the molecular structure and atom connectivity for (I), as illustrated in Fig. 1. The benzocarbazole ring is planar, with bond distances and angles comparable to those reported similiar structures (Hökelek et al., 1998; Hosomi et al., 2000). The mean planes of the benzo(b)carbazole and phenyl rings form a dihedral angle of 79.26 (5)°. The N1—S1—C1 plane is almost orthogonal to carbazole ring [dihedral angle 87.20 (7)°] and phenyl ring [dihedral angle 88.44 (7)°]. The best plane of pyrrole ring N1/C7/C12/C13/C22 subtends a dihedral angle of 28.11 (11)° with sulfonyl group.

The average S—O, S—C, and S—N distances are 1.418, 1.760 and 1.664 Å, respectively, in (I); these are comparable as observed in similiar structures (Chakkaravarthi et al., 2007; Sankaranarayanan et al., 2000). The N—C bond lengths, namely N1—C7 and N1—C22 [1.430 (2) & 1.434 (2) Å in (I)] deviate slightly from the normal mean value reported in the literature (Allen et al., 1987). This indicates that the substitution of the phenylsulfonyl group at atom N1 results in an lengthening of the C—N bond lengths. This may be due to the electron-withdrawing character of the phenylsulfonyl group (Govindasamy et al., 1998). The S atom exhibits significant deviation from that of a regular tetrahedron, with the largest deviations being seen for the O—S—O [O1—S1—O2 119.66 (7)°] and O—S—N angles [O1—S—N1 106.78 (7)°]. The widening of the angles may be due to repulsive interactions between the two short S=O bonds, similar to what is observed in related structures (Chakkaravarthi et al., 2008; Rodriguez et al., 1995).

The sum of the bond angles around N1 [350.99°] indicate the sp² hybridized state of the atom N, in the molecule. The benzene ring C15—C20 is almost coplanar with methyl groups [torsion angles C24—C19—C20—C21 and C15—C16—C17—C23 (0.17 (30)° and -179.18 (22)°, respectively] The torsion angles O1—S1—N1—C7 and O1—S1—C1—C6 [43.11 (16)° and 22.47 (20)°, respectively] describe the syn conformation of the phenylsulfonyl group with respect to benzocarbazole ring system. This conformation is influenced by the intramolecular C—H··· O hydrogen bonds (Table 1), C8—H8··· O1 and C21—H21···O2, involving sulfonyl atoms O1 and O2.

In addition, intramolecular C8—H8···O1 and C21—H21···O2 hydrogen bonds form six-membered rings, both with a graph-set motif of S(6) (Etter et al., 1990). The crystal packing exhibits weak intermolecular C—H···π interactions, involving the C7—C12 (centroid Cg1) and C15—C20 (centroid Cg2) rings (Table 1) [Fig. 2].