Dimethyl 3,3′-(phenyl­methyl­ene)bis­(1H-indole-2-carboxyl­ate)

Hong-Shun Sun; Yu-Long Li; Ning Xu; Hong Xu; Ji-Dong Zhang

doi:10.1107/S1600536813024471

. 2013 Sep 7;69(Pt 10):o1516. doi: 10.1107/S1600536813024471

Dimethyl 3,3′-(phenylmethylene)bis(1H-indole-2-carboxylate)

Hong-Shun Sun ^a,^*, Yu-Long Li ^a, Ning Xu ^a, Hong Xu ^a, Ji-Dong Zhang ^a

PMCID: PMC3790385 PMID: 24098207

Abstract

In the title compound, C₂₇H₂₂N₂O₄, the two indole ring systems are approximately perpendicular to each other, with a dihedral angle of 84.5 (5)° between their planes; the benzene ring is twisted with respect to the two indole ring systems at angles of 78.5 (5) and 86.5 (3)°. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, weak C—H⋯O and C—H⋯N hydrogen bonds, and C—H⋯π interactions into a three-dimensional supramolecular architecture.

Related literature

For applications of indole derivatives, see: Poter et al. (1977 ▶); Sundberg (1996 ▶); Chang et al. (1999 ▶); Ge et al. (1999 ▶); Ni (2008 ▶); Sun et al. (2012 ▶).

Experimental

Crystal data

C₂₇H₂₂N₂O₄
M _r = 438.47
Monoclinic,
a = 13.604 (3) Å
b = 15.560 (3) Å
c = 11.274 (2) Å
β = 112.66 (3)°
V = 2202.2 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonis CAD-4 diffractometer
4196 measured reflections
4021 independent reflections
2322 reflections with I > 2σ(I)
R _int = 0.028
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.181
S = 1.00
4021 reflections
298 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536813024471/xu5723sup1.cif

e-69-o1516-sup1.cif^{(23.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813024471/xu5723Isup2.hkl

e-69-o1516-Isup2.hkl^{(197.1KB, hkl)}

Click here for additional data file.^{(8.6KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813024471/xu5723Isup3.cml

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

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

Cg1 and Cg4 are the centroids of the N1-pyrrole and C15-benzene rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯O2ⁱ	0.86	2.02	2.870 (4)	169
C11—H11A⋯O3ⁱⁱ	0.96	2.60	3.221 (4)	123
C11—H11B⋯N1ⁱⁱⁱ	0.96	2.61	3.443 (5)	145
C11—H11C⋯O4ⁱ	0.96	2.53	3.333 (5)	142
C5—H5A⋯Cg4^iv	0.93	2.76	3.659 (4)	164
C11—H11B⋯Cg1ⁱⁱⁱ	0.96	2.55	3.366 (4)	143
C21—H21B⋯Cg4ⁱ	0.96	2.73	3.516 (5)	139

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

Acknowledgments

The work was supported by the research fund of Nanjing College of Chemical Technology (grant No. NHKY-2013–02).

supplementary crystallographic information

1. Comment

Indole derivatives are found abundantly in a variety of natural plants and exhibit various physiological properties (Poter et al., 1977; Sundberg, 1996). Among them, bis-indolymethane derivatives are found to be kinds of potentially bioactive compounds (Chang et al., 1999; Ge et al., 1999). In recent years, the synthesis and application of bis-indolymethane derivatives have been widely studied. The title compound is one of bis-indolymethane derivatives as a precursor for MRI Contrast Agents(Ni, 2008). We report here its crystal structure.

The molecular structure of the title compound is shown in Fig. 1. The benzene ring is twisted to the two indole rings with the dihedral angles of 101.5 (5) and 93.5 (3)°, respectively. Two indole rings make a dihedral angle of 84.5 (5)° to each other.

As shown in Figure 2, the molecules are linked by N—H···O and C—H···O and C—H···N hydrogen bonds into dimers in the crystal lattice. The structural parameters for the intermolecular hydrogen bonds resulting in the formation of dimers are given in Table 1.

2. Experimental

Methyl indole-2-carboxylate (17.5 g, 100 mmol) was dissolved in 200 ml methanol; commercially available benzaldehyde (5.3 g, 50 mmol) was added and the mixture was heated to reflux temperature. Concentrated HCl (3.7 ml) was added and the reaction was left for 1 h. After cooling the white product was filtered off and washed thoroughly with methanol. The reaction can be followed by TLC (CHCl₃:hexane = 1:1). Yield was 93%. Crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution.