(E)-3-(9-Hexyl-9H-carbazol-3-yl)acrylic acid

In the title compound, C₂₁H₂₃NO₂, the hexyl group adopts an extended conformation, the six C atoms are nearly coplanar [maximum deviation = 0.082 (3) Å] and their mean plane is approximately perpendicular to the carbazole ring system, with a dihedral angle of 78.91 (15)°. In the crystal, mol­ecules are linked by O—H...O hydrogen bonds, forming inversion dimers; π–π stacking between carbazole ring systems of adjacent dimers further links the dimers into supra­molecular chains propagating along the b-axis direction [centroid-to-centroid distances = 3.868 (2) and 3.929 (2) Å].