(E)-N′-[(E)-3-(4-Hydroxy-3-methoxyphenyl)allylidene]isonicotinohydrazide

In the title compound, C16H15N3O3, the dihedral angle between the pyridine and benzene rings is 7.66 (5)°. The crystal packing is consolidated by intermolecular C—H⋯O and O—H⋯N interactions, which link the molecules into zigzag chains propagating along [010]. The chains are further linked into a three-dimensional network by N—H⋯O, C—H⋯N, C—H⋯O and C—H⋯π interactions.

In the title compound, C 16 H 15 N 3 O 3 , the dihedral angle between the pyridine and benzene rings is 7.66 (5) . The crystal packing is consolidated by intermolecular C-HÁ Á ÁO and O-HÁ Á ÁN interactions, which link the molecules into zigzag chains propagating along [010]. The chains are further linked into a three-dimensional network by N-HÁ Á ÁO, C-HÁ Á ÁN, C-HÁ Á ÁO and C-HÁ Á Á interactions.

Comment
In the search of new compounds, isoniazid derivatives have been found to possess potential tuberculostatic activities (e.g. Janin, 2007). As a part of a current work of synthesis of (E)-N'-substituted isonicotinohydrazide derivatives, we present the crystal structure of the title compound, (I), (Fig. 1).

Experimental
The isoniazid derivative was prepared following the procedure by Lourenco et al. (2008). (E)-N'-[(E)-3-(4-hydroxy-3-methoxyphenyl) allylidene]isonicotinohydrazide was prepared by reaction between the 4-hydroxy-3-methoxy cinnamaldehyde (1.0 eq) with isoniazid (1.0 eq) in ethanol/water. After stirring for 1-3 h at room temperature, the resulting mixture was concentrated under reduced pressure. The residue, purified by washing with cold ethanol and ethyl ether, afforded the pure derivative. Yellow needles of (I) were obtained by recrystallization from methanol.

Refinement
Atoms H1N2 and H1O2 were located in a difference Fourier map and refined freely. The remaining H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.96 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating-group model was applied for the methyl groups.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1