2-((E)-{[4-(Hydroxymethyl)phenyl]imino}methyl)phenol

The title compound, C14H13NO2, adopts the enol–imine tautomeric form, with an intramolecular O—H⋯N hydrogen bond which generates an S(6) ring motif. The dihedral angle between the aromatic rings is 7.85 (7)°. The crystal structure is stabilized by O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, forming a two-dimensional array that stacks along the a axis. In addition, a C—H⋯π interaction contributes to the stabilization of the crystal packing.


Maharramov Comment
Schiff base compounds are important class of materials due to their flexibility, structural similarities with natural biological substances and also due to presence of imine (-N=CH-) which relates to the mechanism of transformation and racemisation reactions in biological system (Rajavel et al., 2008). Schiff bases-bimolecular condensation products of amnio alcohols with aldehydes represent valuable intermediates in organic synthesis with various applications (Uğraş et al., 2006). Schiff bases resulted from aromatic aldehydes ortho-substituted with a hydroxyl group initially aroused interest due to the several donor atoms in their structures which give them an advantage to form a water soluble transition metal complexes (Wadher et al., 2009). This advantage raises potential applications in water treatment (Elena et al., 2000). They could also act as valuable ligands whose biological activity has been shown to increase on complexation (Mohamed et al., 2006).
In the crystal, molecules are linked by O-H···O and weak C-H···O hydrogen bonds, forming a two dimensional array that stacks along the a axis Fig. 2 and Table 1. The crystal packing is further stabilized by C-H···π interactions, Table 1.

Experimental
The title compound was synthesized as a secondary product from a three component reaction of cyclohexane-1,3-dione (1 mmol), (4-aminophenyl)methanol (1 mmol), and salicylaldehde (1 mmol). The reaction mixture was refluxed in ethanol at 351 K for four hours then left at room temperature for two days. The resulting solid product was filtered of, dried and recrystallized from ethanol. (43% yield, M.pt: 403 K). Crystals suitable for X-ray diffraction were grown in a diluted ethanol solution at room temperature by the slow evaporation method.

Figure 1
A view of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.

Figure 2
The crystal packing and hydrogen bonding of (I), viewed along the b axis. H atoms not involved in hydrogen bonds have been omitted for clarity.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.