2-(4-hydroxyphenyl)-1H-benzimidazol-3-ium chloride monohydrate

The title molecular salt, C₁₃H₁₁N₂O ⁺·Cl^-·H₂O, crystallizes as a monohydrate. In the cation, the phenol and benzimidazole rings are almost coplanar, making a dihedral angle of 3.18 (4)°. The chloride anion and benzimidazole cation are linked by two N⁺ - H⋯Cl^- hydrogen bonds, forming chains propagating along [010]. These chains are linked through O - H⋯Cl hydrogen bonds involving the water molecule and the chloride anion, which form a diamond core, giving rise to the formation of two-dimensional networks lying parallel to (10-2). Two π-π interactions involving the imidazolium ring with the benzene and phenol rings [centroid-centroid distances = 3.859 (3) and 3.602 (3) Å, respectively], contribute to this second dimension. A strong O - H⋯O hydrogen bond involving the water molecule and the phenol substituent on the benzimidazole unit links the networks, forming a three-dimensional structure.