3-[1-(3-Hydroxybenzyl)-1H-benzimidazol-2-yl]phenol dimethyl sulfoxide monosolvate

Crystals of the title compound were obtained as a 1:1 dimethyl sulfoxide solvate, C20H16N2O2·C2H6O. The molecular conformation of the organic molecule is similar to that in the previously reported unsolvated structure [Eltayeb et al. (2009 ▶). Acta Cryst. E65, o1374–o1375]. Thus, the dihedral angles formed by the benzimidazole moiety with the two benzene rings are 57.54 (4) and 76.22 (5)°, and the dihedral angle between the benzene rings is 89.23 (5)°. In the crystal, a three-dimensional network features O—H⋯O, O—H⋯N and O—H⋯S hydrogen bonds, as well as C—H⋯O and C—H⋯π interactions.

Cg1, Cg2 and Cg3 are the centroids of the C4-C9, C11-C16 and C17-C22 rings, respectively. Benzimidazole and its derivatives are of significant importance in medicinal chemistry. In these species, the presence of the benzimidazole heterocycle provides a vast variety of potential biological and clinical applications (Narasimhan et al., 2012). Benzimidazole derivatives with potential biological activities have been widely studied for the treatment of different illnesses such as cancer (Alper et al., 2003), infectious diseases, metabolic and cardiovascular disorders, allergies, tuberculosis (Sharma et al., 2011) and different inflammatory conditions. Thus, in order to increase the activity of benzimidazole derivatives its coordination behaviour with transition metals such as Pd(II), Co(II), Ni(II), Cu(II) and Cd(II) (Tellez et al., 2008) has been explored.
In this molecule, the dihedral angles formed by the benzimidazole moiety with the two benzene rings (C11-C16 and

Experimental
To a solution of 3-hydroxybenzaldehyde (0.320 g, 2.0 mmol) in CH 2 Cl 2 , 0.034 g (0.2 mmol) of p-toluenesulfonic acid, 0.7 g of o-phenylenediamine (6.4 mmol) and molecular sieves were added. The mixture was stirred at room temperature for 24 h. After this time the resulting solution was filtered and the solvent evaporated under vacuum affording 3-[1-(3-Hydroxybenzyl)-1H-benzimidazol-2-yl]phenol as a microcrystalline white powder. Single crystals suitable for X-ray diffraction analysis were obtained from a dimethyl sulfoxide solution of the compound.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme.

Figure 2
A two-dimensional sheet structure formed through hydrogen bonds interactions parallel to the plane ac, hydrogen bonds are showing by dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.23 e Å −3 Δρ min = −0.32 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.