Received 5 December 2011
In the title compound, C9H6ClNO2, the carboxyl group is twisted from the indole ring system by 9.00 (8)°. In the crystal, inversion dimers linked by pairs of O-HO hydrogen bonds generate R22(8) loops and N-HO hydrogen bonds link the dimers into (001) sheets. Aromatic - stacking interactions [centroid-centroid distance = 3.7185 (12) A °] are also observed.
Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB6559 ).
We thank Southeast University for support.
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