1-[6-(1H-Indol-1-yl)pyridin-2-yl]-1H-indole-3-carbaldehyde

In the title compound, C22H15N3O, the dihedral angle between the two indole units is 33.72 (3)°. The molecular structure features a weak intramolecular C—H⋯N interaction. In the crystal, weak C—H⋯O and C—H⋯π interactions, forming a two-dimensional network parallel to the bc plane.

CR acknowledge the AMET University management, India, for their kind support.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG5369).

Comment
The chemistry of indole has been of increasing interest, since several compounds of this type possess diverse biological activities (Macor et al., 1992). These derivatives exhibit antibacterial, antifungal (Singh et al., 2000) and antitumour activities (Andreani et al., 2001). Some of the indole alkaloids extracted from plants possess interesting cytotoxic and antiparasitic properties (Quetin-Leclercq, 1994;Mukhopadhyay et al., 1981).

Experimental
To a stirred solution of dimethylformamide (2.10g, 28.70 mmol) at 0°C, added phosphorous oxycholoride (1.10g, 7.17 mmol) drop wise under nitrogen atmosphere. 2,6-bis(N-indolyl)pyridine (1.0g, 3.23 mmol) in dimethylformamide was then added to the reaction at 0°C to 10°C. After the completion of addition, the reaction mixture was allow to attain room temperature and then stirred for additional one hour at 35°C. The reaction was then quenched by adding crushed ice (100 g) and further water (100 ml). Then the reaction mixture was then treated thrice with NaOH solution (1M). The reaction mixture was heated after adding one portion of NaOH solution and the rest of the two portions were added later with stirring. The reaction mixture was then kept in refrigerator overnight. The precipitate obtained was collected by filtration and then dissolved in chloroform (2 x 100 ml). The organic layer was then dried over (Na 2 SO 4 ), filtered and solvent was evaporated under reduced pressure to give the residue which was then chromatographed over SiO 2 using hexane: chloroform (1:4) as eluting solvent to give the mono aldehyde(27%) as a colourless solid and further elution with CHCl 3 : methanol (99:1) afforded the corresponding dialdehyde (55%).

Refinement
H atoms were positioned geometrically and refined using riding model with C-H = 0.93 Å and U iso (H) = 1.2Ueq(C) for aromatic C-H.