2-(1H-Benzimidazol-2-yl)phenol

The title molecule, C13H10N2O, is essentially planar, the maximum deviation from the plane of the non-H atoms being 0.016 (2) Å. The imidazole ring makes a dihedral angle of 0.37 (13)° with the attached benzene ring. An intramolecular O—H⋯N hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked through N—H⋯O hydrogen bonds, forming chains propagating in [001]. The crystal packing also features four π–π stacking interactions involving the imidazole ring, fused benzene ring and attached benzene ring system [centroid–centroid distances = 3.6106 (17), 3.6108 (17), 3.6666 (17) and 3.6668 (17) Å].


Experimental
SMP thanks Annamaliar College of Engineering, Mudaiyur, for providing constant support for this research study. NS is thankful to SÁK.P. Engineering College, Thiruvannamalai, for providing constant support for this research work.

Comment
Imidazole derivatives have occupied a unique place in the field of medicinal chemistry. Many of the substituted imidazoles are known as inhibitors of P38 map kinase, fungicides and herbicides and therapeutic agents (Nakamura et al., 2004;Su Han & Kim, 2001). Being a polar and ionisable aromatic compounds, it improves pharmacokinetic characteristics of lead molecules and thus used as a remedy to optimize solubility and bioavailability parameters of proposed poorly soluble lead molecules. The imidazole ring is a constituent of several important natural products, including purine, histamine, histidine and nucleic acid (Roman et al., 2007;Congiu et al., 2008). Owing to the wide range of pharmacological and biological activities, the synthesis of imidazoles has become an important target in current years.

Experimental
To the pure o-phenylenediamine (1.6 g, 15 mmol) in ethanol (10 ml), 2-hydroxybenzaldehyde (1.6 g, 15 mmol) and ammonium acetate (3 g) was added about 1 h by maintaining the temperature at 353 K. The reaction mixture was refluxed for 48 hrs and extracted with dichloromethane. The solid separated was purified by column chromatography using benzene as the eluent. Yield: 1.89 g; 60%. The compound was dissolved in benzene and ethyl acetate (9:1) mixture and allowed to slow evaporation for two days, to obtain crystals suitable for X-ray diffraction studies.

Refinement
The N-bound H atom was located in a difference Fourier map and refined freely; N1-H1 = 0.91 (2) Å. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with O-H = 0.82 and Csp 2 -H = 0.93 Å.

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.   Part of the crystal structure of compound, showing the formation of π-π stacking interactions.