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Abstract : In the title compound, C 25 H 15 Cl 2 NO 4 S, the dichlorophenyl ring is twisted by 68.69 (11) from the mean plane of the carbazole ring system [r.m.s. deviation = 0.084 (2) ]. The hydroxy group is involved in an intramolecular O—HÁ Á ÁO hydrogen bond, which generates an S(6) graph-set motif. In the crystal, pairs of C—HÁ Á ÁCl hydrogen bonds link molecules into inversion dimers with an R 2 2 (26) motif. Weak C—HÁ Á ÁO interactions further link these dimers into ribbons propagating in [100]. In continuation of our studies of carbazole derivatives, which are found to possess various biological activities, such as anti-oxidative (Tachibana et al., 2001), anti-inflammatory and antimutagenic (Ramsewak et al., 1999), antibiotic, antifungal and cytotoxic (Chakraborty et al., 1965, 1978), we report herein on the synthesis and crystal structure of the title compound (I) (Fig. 1). The geometric parameters of (I) agree well with those reported for related structures [Chakkaravarthi et al. 2008, 2009]. The C1–C6 phenyl ring makes a dihedral angle of 79.76 (11) with the carbazole ring system (C7–C18/N1). The dichlorophenyl ring (C21–C25) is twisted by 68.69 (11) from the mean plane of the carbazole ring system and inclined at an angle of 32.22 (13) to the phenyl ring. Atom S1 has a distorted tetrahedral configuration. The widening of angle O1—S1—O2 [120.49 (11) ] and narrowing of angle N1—S1—C1 [105.36 (10) ] from the ideal tetrahedral values are attributed to the Thorpe–Ingold effect (Bassindale, 1984). As a result of the electron–withdrawing character of the The hydroxy group is involved in an intramolecular O— HÁ Á ÁO hydrogen bond (Table 1), which generates an S(6) graph-set motif. In the crystal, pairs of C—HÁ Á ÁCl hydrogen bonds link molecules into inversion dimers with an R 2 2 (26) motif (Bernstein et al., 1995), and weak C—HÁ Á ÁO interactions further link these dimers into ribbons propagating in [100] (Table 1 and Fig. 2). Enamine 16 g (500 mg, 0.95 mmol) was reacted with CuBr 2 (212 mg, 0.95 mmol) in dry DMF (20 ml) at reflux for 1 h under N 2. The reaction mass was poured over crushed ice (50 ml) containing concentrated HCl (1 ml). The precipitated solid was filtered, washed with water and air-dried to obtain the crude compound, which was purified by flash column chromatography on silica gel (230–420 mesh, n-hexane/ethyl acetate, 7:3) to afford …