N′-[(E)-3-Indol-3-ylmethylene]isonicotinohydrazide monohydrate

Crystals of the title compound, C15H12N4O·H2O, were obtained from a condensation reaction of isonicotinylhydrazine and 3-indolylformaldehyde. The molecule assumes an E configuration, with the isonicotinoylhydrazine and indole units located on the opposite sites of the C=N double bond. In the molecular structure the pyridine ring is twisted with respect to the indole ring system, forming a dihedral angle of 44.72 (7)°. Extensive classical N—H⋯N, N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonding and weak C—H⋯O interactions are present in the crystal structure.

Crystals of the title compound, C 15 H 12 N 4 OÁH 2 O, were obtained from a condensation reaction of isonicotinylhydrazine and 3-indolylformaldehyde. The molecule assumes an E configuration, with the isonicotinoylhydrazine and indole units located on the opposite sites of the C N double bond. In the molecular structure the pyridine ring is twisted with respect to the indole ring system, forming a dihedral angle of 44.72 (7) . Extensive classical N-HÁ Á ÁN, N-HÁ Á ÁO, O-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonding and weak C-HÁ Á ÁO interactions are present in the crystal structure.

Comment
The hydrazone derivatives has attracted our much attention because they have shown to be potential DNA damaging and mutagenic agents (Okabe et al., 1993). As part of the ongoing investigation on the relationship between structure and property of hydrazone derivatives (Shan et al., 2003;Qiang et al., 2007) the title compound has recently been prepared in our laboratory and its crystal structure is reported here.
The molecular structure of the title compound is shown in Fig. 1. The pyridine ring is twisted with respect to the indole ring system by a dihedral angle of 44.72 (7)°. The N2-C9 bond distance of 1.293 (3) Å shows a typical C═N double bond.
The isonicotinoylhydrazine and indole moieties are located on the opposite sites of the CN bond, thus the molecule assumes an E configuration, which agrees with those found in ethanol solvate compound (Jing et al., 2006) and methanol solvate compound (Tai et al., 2003).
The extensive classic hydrogen bonding and weak C-H···O hydrogen bonding are present in the crystal structure (Table   1).

Experimental
Isonicotinylhydrazine (1.37 g, 0.01 mol) was dissolved in ethanol (50 ml), the solution was heated at about 333 K for several minutes until the solution cleared. An ethanol solution (20 ml) containing 3-indolylformaldehyde (1.45 g, 0.01 mol) was dropped slowly into the above solution with continuous stirring, and the mixture solution was refluxed for 1.5 h. When the solution had cooled to room temperature, colorless powder crystals appeared. The powder crystals were separated from the solution and washed with cold water three times. Recrystallization was performed twice with a mixture solvent of 2-propanol-water (1:1 v/v), to obtain single crystals of the title compound.

Refinement
Water and imino H atoms were located in a difference Fourier map and were refined as riding in as-found relative positions, U iso (H) = 1.5U eq (N,O). Methyl H atoms were placed in calculated positions with C-H = 0.96 Å and torsion angle was refined to fit the electron density, U iso (H) = 1.5U eq (C). Other H atoms were placed in calculated positions with C-H = 0.93 Å, and refined in riding mode with U iso (H) = 1.2U eq (C).