4-Chloro-2-[(E)-(4-fluorophenyl)iminomethyl]phenol

In the title Schiff base molecule, C13H9ClFNO, the benzene rings are twisted slightly with respect to each other, making a dihedral angle of 7.92 (2)°. An intramolecular O—H⋯N hydrogen bond occurs. In the crystal, an infinite chain is formed along the c-axis direction by π–π stacking interactions between the phenyl rings and the six-membered hydrogen-bonded ring of neighboring Schiff base ligands [centroid–centroid distances of 3.698 (2) and 3.660 (3) Å]. Neighboring chains are linked into a three-dimensional supramolecular structure by C—H⋯O and C—H⋯F hydrogen bonds.

In the title Schiff base molecule, C 13 H 9 ClFNO, the benzene rings are twisted slightly with respect to each other, making a dihedral angle of 7.92 (2) . An intramolecular O-HÁ Á ÁN hydrogen bond occurs. In the crystal, an infinite chain is formed along the c-axis direction bystacking interactions between the phenyl rings and the six-membered hydrogenbonded ring of neighboring Schiff base ligands [centroidcentroid distances of 3.698 (2) and 3.660 (3) Å ]. Neighboring chains are linked into a three-dimensional supramolecular structure by C-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds.
The author acknowledges Lanzhou Jiaotong University for supporting this work.

Comment
Schiff bases are considered important compounds because of their wide range of biological activities, and also because of their use as ligands in conjunction with transition metals. Schiff base ligands usually coordinate to a metal ion through the imine nitrogen atom, but coordination via other functional groups, e.g. through oxygen or carbon, has also been reported (Ebrahimipour et al., 2012;Guo et al., 2013). Schiff bases derived from salicyladehyde and fluoroaniline, specifically, have been considered as potential pharmaceutically interesting compounds as several of the members of this family of molecules have shown antitumor, antimicrobial or antiviral activities (Sawada et al., 2001;Ma et al., 2013;Siddiqui et al., 2006). As an extension of our work on the structural characterization of Schiff base compounds, the solid state structure of the title compound is reported.
Finally, neighboring chains are linked into a three-dimensional supramolecular structure by weak C-H···O and C-H···F hydrogen bonding interactions (Fig. 2 Table 1).

Refinement
H atoms were fixed geometrically and treated as riding with O-H = 0.82 Å (hydroxy) and C-H = 0.93 Å, U iso (H) = 1.2 U eq (C) for aromatic H atoms and U iso (H) = 1.5 U eq (O) for the hydroxy H atom. The hightest residual electron density peak is located 0.91 Å from H1 and the deepest hole is located 0.91 Å from C13.

Figure 1
The molecular structure of the title compound, showing 30% probability displacement ellipsoids.    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.19 e Å −3 Δρ min = −0.23 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.