Synthesis and crystal structure of 1-hydroxy-8-methyl-9H-carbazole-2-carbaldehyde

Two crystallographically independent molecules are present in the asymmetric unit of the title compound, C14H11NO2, with virtually identical geometries. The carbazole units are planar. The hydroxy group at position 1, carbaldehyde group at position 2, and methyl group at position 8 (with the exception of two H atoms) are coplanar with the attached benzene rings. The dihedral angle between the two benzene rings is 2.20 (9)° in molecule A and 2.01 (9)° in molecule B. The pyrrole ring makes dihedral angles of 0.82 (10) and 1.40 (10)° [0.84 (10) and 1.18 (10)° in molecule B] with the (–CH3)-substituted and (–OH and –CHO) substituted benzene rings, respectively. The molecular structure is stabilized by the intramolecular O—H...O hydrogen bonds, while the crystal structure features N—H...O and C—H...O hydrogen bonds. A range of π–π contacts further stabilizes the crystal structure.