Monoclinic polymorph of 4-[(1H-benz­imidazol-1-yl)meth­yl]benzoic acid

Three polymorphs of the title compound, C(15)H(12)N(2)O(2), were obtained accidentally as single crystals in the hydro­thermal reaction of the title compound with manganese bromide in the presence of N,N′-dimethyl­formamide at 373 K. Here we report the structure of the first polymorph. The benzimidazole ring is almost planar, the maximum deviation from the mean plane being 0.016 (1) Å. The benzimidazole and benzene rings are approximately perpendicular, making a dihedral angle 85.56 (7)°, which is a reflection of the axial rotation of the flexible benzimidazolyl arm. In the crystal, adjacent mol­ecules are connected through O—H⋯N hydrogen bonds into a chain along [100], and neighboring chains are further linked by via weak C—H⋯O hydrogen-bonding inter­actions, forming a two-dimensional network.