1-{(E)-[(2-Fluoro-5-nitrophenyl)imino]methyl}naphthalen-2-ol

The title molecule, C17H11FN2O3, is nearly planar [maximum deviation = 0.197 (1) Å] and the molecular conformation is stabilized by an N—H⋯O hydrogen bond forming an S(6) ring motif. The H atom of the intramolecular hydrogen bond was found to be disordered over two sites and thus both the hydroxy and keto tautomers are simultaneously present in the solid. Refinement of the occupancy of this site suggests that the hydroxy form is the major component [occupancy refined to 0.59 (3):0.41 (3)]. Bond lengths are also largely consistent with dominance of the hydroxy form. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to (101). π–π stacking interactions [centroid–centroid distances = 3.5649 (9) and 3.7579 (9) Å] inter-connect these layers.


Miller Comment
Schiff bases have been widely studied due to their importance in industrial and biological applications. They serve for example as, antibacterial, antifungal, anticancer (Sari et al., 2003, Verma et al., 2004 and herbicidal agents (Cozzi, 2004;Chandra & Sangeetika, 2004). It is well known that the introduction of fluorine atom into an organic molecule causes dramatic changes in its biological profile (Blair et al., 2000), mainly due to the high electronegativity of fluorine.
Incorporating fluorine increases fat solubility, improving the drug's partitioning into membranes and hence increasing bioavailability (LeBars et al., 1987). Fluorination can also aid hydrophobic interactions between the drug and binding sites on receptors or enzymes (Kirk et al., 1979). Further to our study in synthesis of fluorinated bioactive compounds we herein report the synthesis and crystal structure of the title compound.
As seen in Fig (2) and -9.7 (2) °, respectively. All bond lengths and angles are similar to those of a related structure previously reported (Akkurt et al., 2012).

Experimental
The title compound was obtained unintentionally in a good yield from a three components reaction by heating of 1 mmol (172 mg) 2-hydroxynaphthalene-1-carbaldehyde, 1 mmol (156 mg) 2-fluoro-5-nitroaniline and 1 mmol (188 mg) 5phenylcyclohexane-1,3-dione in ethanol for 8 h at 350 K. The solvent was evaporated under vacuum and the resulting solid was crystallized from a mixture of ethanol and few drops of acetone. Yellow rods of product (M.p. 471 K) were collected (73% yield) of sufficient quality for X-ray diffraction.

Refinement
Difference synthesis suggested a disordered model for H1 was appropriate. Refinement over two sites with thermal displacement ellipsoids constrained to be equal and with both O1-H1 and N1-H2 distances restrained to 0.88 (1)  geometrically optimized positions and constrained to ride on their parent atoms with C-H = 0.95 (aromatic) Å and with U iso (H) = 1.2U eq (C).

Figure 1
The title compound with the atom numbering scheme.  The molecular packing of the title compound viewed along the b axis, showing the two dimensional layers parallel to (101). Hydrogen bonds are drawn as dashed lines.

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.