3-(1H-Indol-3-yl)-2-(2-nitro­benzene­sulfonamido)­propanoic acid including an unknown solvate

Islam Ullah Khan; Hafiz Mubashar-ur-Rehman; Salman Aziz; William T A Harrison

doi:10.1107/S1600536812023446

. 2012 Jun 13;68(Pt 7):o2019. doi: 10.1107/S1600536812023446

3-(1H-Indol-3-yl)-2-(2-nitrobenzenesulfonamido)propanoic acid including an unknown solvate

Islam Ullah Khan ^a,^*, Hafiz Mubashar-ur-Rehman ^a, Salman Aziz ^a, William T A Harrison ^b

PMCID: PMC3393288 PMID: 22807845

Abstract

In the title compound, C₁₇H₁₅N₃O₆S, which crystallized with highly disordered methanol and/or water solvent molecules, the dihedral angle between the the indole and benzene ring systems is 5.3 (2)°, which allows for the formation of intramolecular π–π stacking interactions [centroid–centroid separations = 3.641 (3) and 3.694 (3) Å] and an approximate overall U-shape for the molecule. In the crystal, dimers linked by pairs of N_s—H⋯O_c (s = sulfonamide and c = carboxylate) hydrogen bonds generate R ₂ ²(10) loops, whereas N_i—H⋯π (i = indole) interactions lead to chains propagating in [100] or [010]. Together, these lead to a three-dimensional network in which the solvent voids are present as intersecting (two-dimensional) systems of [100] and [010] channels. The title compound was found to contain a heavily disordered solvent molecule, which could be methanol or water or a mixture of the two. Due to its uncertain nature and the unresolvable disorder, the data were processed with the SQUEEZE option in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155], which revealed 877.8 Å³ of solvent-accessible volume per unit cell and 126 electron-units of scattering density or 109.7 Å³ (16 electron units) per organic molecule.. This was not included in the calculations of overall formula weight, density and absorption coefficient.

Related literature

For related structures and background references to the biological activity of sulfonamides, see: Khan et al. (2011a ▶,b ▶). For further synthetic details, see: Deng & Mani (2006 ▶).

Experimental

Crystal data

C₁₇H₁₅N₃O₆S
M _r = 389.38
Tetragonal,
a = 9.6818 (5) Å
c = 44.017 (3) Å
V = 4126.0 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.19 mm⁻¹
T = 296 K
0.30 × 0.25 × 0.10 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
4042 measured reflections
4042 independent reflections
3492 reflections with I > 2σ(I)

Refinement

R[F ² > 2σ(F ²)] = 0.067
wR(F ²) = 0.168
S = 1.07
4042 reflections
245 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.24 e Å⁻³
Absolute structure: Flack (1983 ▶), 1581 Friedel pairs
Flack parameter: 0.03 (15)

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812023446/sj5218sup1.cif

e-68-o2019-sup1.cif^{(20.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812023446/sj5218Isup2.hkl

e-68-o2019-Isup2.hkl^{(198.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812023446/sj5218Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Cg1ⁱ	0.86	2.77	3.565 (4)	155
N2—H2⋯O1ⁱⁱ	0.86	2.10	2.918 (4)	158

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors acknowledge the Higher Education Commission of Pakistan for providing a grant for the project to strengthen the Materials Chemistry Laboratory at GC University Lahore, Pakistan.

supplementary crystallographic information

Comment

As part of our ongoing studies of chiral sulfonamides with possible biological activity (Khan et al., 2011a,b), we now report the structure of the title compound, (I). Compound (I) was found to contain a heavily disordered solvent molecule, which could be methanol or water or a mixture of the two. Due to its uncertain nature and the unresolvable disorder, the data were processed with the SQUEEZE option in PLATON (Spek, 2009), to remove the solvent contribution to the scattering.

The molecular structure of (I) (Fig. 1) approximates to a U-shape, with the indole ring system (C1—C8/N1; r.m.s. deviation = 0.007 Å) and benzene ring (C12–C17) lying approximately parallel to each other [dihedral angle = 5.3 (2)°]. This allows intramolecular aromatic π-π stacking to occur: the separations of the centroid of the C12–C17 benzene ring with those of the C1–C6 and C1/C6/C7/C8/N1 rings are 3.641 (3) Å and 3.694 (3) Å, respectively. The N3/O5/O6 nitro group is twisted out of the plane of its atttached ring by 48.9 (4)°. The configuration of the stereogenic carbon atom (C10) in (I) is S, which is consistent with that of the equivalent atom in the starting material.

In the crystal, the molecules are linked into dimers via pairs of N_s–H···O_c (s = sulfonamide, c = carboxylate) hydrogen bonds (Fig. 2, Table 1), which result in R₂²(10) loops. A crystallographic twofold axis directed along [110] generates the second molecule from the asymmetric molecule. In addition, weak N_i—H···π (i = indole) interactions occur: these lead to [100] chains for the asymmetric molecule and [010] chains for symmetry-generated molecules in other locations in the unit-cell (Fig. 3). The carboxylic acid O—H group is directed towards the solvent void and probably forms a hydrogen bond to the solvent.

Together, the N–H···O and N–H···π bonds generate a three-dimensional network of molecules within the distinctive "tall" tetragonal unit-cell (Fig. 3). The solvent voids are apparent as square grids of intersecting [100] and [010] pseudo channels lying at z = 0, z = 1/4 and symmetry equivalent locations.

The molcular conformation and crystal structure (Khan et al., 2011a) of the closely related compound 3-(1H-indol-3-yl)-2-(toluene-4-sulfonylamino)-propionic acid monohydrate, (II), are completely different to (I). In (II), where a para-toluene substituent has replaced the 2-nitrobebzene substituent in (I), the organic molecule adopts an extended Z-shaped conformation and no intramolecular π-π stacking can occur. In the crystal of (II), in which the solvent water molecule was located, N_s–H···O_s hydrogen bonds and O_c–H···O_w (s = sulfonamide, c = carboxylic acid, w = water) hydrogen bonds generate chains and the crystal symmetry is monoclinic. Another feature of (II) not seen in (I) is the presence of a short intermolecular C—H···O interaction arising from the α (chiral) C atom (Khan et al., 2011b). However, it is interesting to note that (I) and (II) both feature an unusual N_i–H···π (i = indole) interaction.

Experimental

The title compound was prepared following the literature method (Deng & Mani, 2006) and recrystalized from methanol by slow evaporation to yield yellow blocks of (I).