The mol-ecular and crystal structures of 2-(3-hy-droxy-prop-yl)benzimidazole and its nitrate salt.

2-(3-Hy-droxy-prop-yl)-1 H -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 nitro-gen atom in the imidazole ring. This nitro-gen atom also acts as a proton acceptor. In the crystalline phase, the nitrate salt, namely, 2-(3-hy-droxy-prop-yl)-1 H -benzim-id-azol-3-ium nitrate, C 10 H 13 N 2 O + ·NO 3 - , has been studied. The protonation of the 2-(3-hy-droxy-prop-yl)benzimidazole unit results in significant delocalization of the electron density within the imidazole ring. The salt formation leads to variations in the inter-molecular inter-actions, which were studied by analysis of the Hirshfeld surfaces and two-dimensional fingerprint plots.