The mol­ecular and crystal structures of 2-(3-hy­droxy­prop­yl)benzimidazole and its nitrate salt

2-(3-Hy­droxy­prop­yl)-1H-benzimidazole, C(10)H(12)N(2)O, which has potential biological activity, can be used as a ligand for complexation with metals. This compound is an electron donor, due to the lone pair of the nitro­gen atom in the imidazole ring. This nitro­gen atom also acts as a proton acceptor. In the crystalline phase, the nitrate salt, namely, 2-(3-hy­droxy­prop­yl)-1H-benzim­id­azol-3-ium nitrate, C(10)H(13)N(2)O(+)·NO(3) (−), has been studied. The protonation of the 2-(3-hy­droxy­prop­yl)benzimidazole unit results in significant delocalization of the electron density within the imidazole ring. The salt formation leads to variations in the inter­molecular inter­actions, which were studied by analysis of the Hirshfeld surfaces and two-dimensional fingerprint plots.