Abstract
The asymmetric unit of the title compound, C19H16N2O3, comprises three independent molecules (A, B and C). The inversion-related molecule of A is virtually superimposable upon the other two molecules. In each molecule, there is a twist in the link between the approximately syn carbonyl and amine groups [the N-C-C-O torsion angles range from 19.73 (19) to -21.2 (2)degrees]. Each molecule has a bent shape quantified in terms of the dihedral angle between the indole and indole fused-ring systems [range = 45.69 (5)-47.91 (5)degrees]. In the crystal, the A and B molecules form dimeric aggregates via ten-membered {center dot center dot center dot HNC2O}(2) synthons, while the C molecules self-associate similarly but about a centre of inversion.