N′-[(E)-2-Hydroxy-5-methoxybenzylidene]pyridine-4-carbohydrazide monohydrate

The title compound, C14H13N3O3·H2O, adopts an E conformation with respect to the azomethine bond and crystallizes in the amide form. An intramolecular O—H⋯N hydrogen bond occurs. In the crystal, the lattice water molecule plays a major role in the supramolecular architecture by interconnecting adjacent molecules into a three-dimensional netwrok by means of O—H⋯O, O—H⋯N and N—H⋯O hydrogen-bonding interactions. The structure also features two non-classical C—H⋯O interactions.

The title compound, C 14 H 13 N 3 O 3 ÁH 2 O, adopts an E conformation with respect to the azomethine bond and crystallizes in the amide form. An intramolecular O-HÁ Á ÁN hydrogen bond occurs. In the crystal, the lattice water molecule plays a major role in the supramolecular architecture by interconnecting adjacent molecules into a three-dimensional netwrok by means of O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁO hydrogenbonding interactions. The structure also features two nonclassical C-HÁ Á ÁO interactions.
applications in molecular sensing of metals have received substantial interest during the last decade (Bakir & Brown, 2002).
The compound crystallizes in orthorhombic Pna2 1 space group. The molecule exists in the E configuration with respect to C7=N1 bond (Sithambaresan & Kurup, 2011) which is confirmed by the torsion angle of -177.6 (3)° of C6-C7-N1 -N2 moiety (Fig. 1). The torsion angle of 7.2 (5)° corresponding to N1-N2-C8-O3 moiety supports the cis configuration of the O3 atom with respect to the hydrazine nitrogen atom N1 (Kargar et al., 2010;Shafiq et al., 2009 Incorporation of water molecule in the crystal system of the title compound plays an important role in assembly of the molecules in the lattice through intermolecular hydrogen bonds and makes the crystal system entirely different from the reported one (Kargar et al., 2010). Two classical hydrogen bonds are present in the molecular system ( Fig. 2) between the both H atoms of the water molecule and O3 and N3 atoms of the neighbouring molecules with a D···A distances of 2.764 (4) and 2.874 (5) Å respectively. The phenolic oxygen O2 is involved in an intramolecular hydrogen bond with N1 to form a six membered ring. The hydrazinic nitrogen N2 is also involved in hydrogen bonding with oxygen of solvent water. Two non-classical C-H···O hydrogen bonds are also present in the molecule (Table 1). The packing diagram showing the molecular assembly of the title compound along a axis is shown in Fig. 3.

Experimental
The title compound was prepared by adapting a reported procedure (Mangalam et al., 2009). To a warm ethanolic solution of 2-hydroxy-5-methoxybenzaldehyde (0.152 g, 1 mmol), a methanolic solution of pyridine-4-carbohydrazide (0.137 g, 1 mmol) was added and the resulting solution was refluxed for 45 minutes after adding 3 drops of glacial acetic acid. On cooling the solution, yellow crystals separated out. Single crystals suitable for X-ray diffraction studies were obtained by slow evaporation of its solution in 1:1 mixture of ethanol and DMF.

Refinement
All H atoms on C were placed in calculated positions, guided by difference maps, with C-H bond distances 0.93-0.96 Å.
H atoms were assigned as U iso (H)=1.2Ueq(carrier) or 1.5Ueq (methyl C). N2-H2′ and O2-H2A H atoms were located from difference maps and restrained using DFIX instructions. H atoms of the water molecule were also located from supplementary materials sup-2 Acta Cryst. (2013). E69, o881 difference maps and restrained using DFIX and DANG instructions. Omitted owing to bad disagreement was the reflection (1 1 0). In the absence of significant anomalous scattering effects Friedel pairs have been merged.

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.