1-(2,4-Dinitrophenyl)-2-[(E)-2,4,5-trimethoxybenzylidene]hydrazine

The title compound, C16H16N4O7, is close to being planar, with a dihedral angle of 3.15 (11)° between the benzene rings. The methoxy groups at the ortho- and para-positions of the 2,4,5-trimethoxyphenyl group are almost coplanar with the ring [deviations of the C atoms = 0.017 (2) and −0.025 (2) Å, respectively], whereas the meta-methoxy group deviates slightly [C-atom displacement = 0.162 (2) Å]. Both the ortho- and para-nitro groups are close to being coplanar with their attached ring [dihedral angles = 7.81 (12) and 8.56 (11)°, respectively]. An intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds involving the same H atom as the intramolecular bond generate R 2 2(12) loops. The dimers are linked by weak C—H⋯O interactions into sheets parallel to the (10-4) plane and the sheets are stacked by π–π interactions, with a centroid–centroid distance of 3.5974 (14) Å.

The title compound, C 16 H 16 N 4 O 7 , is close to being planar, with a dihedral angle of 3.15 (11) between the benzene rings. The methoxy groups at the ortho-and para-positions of the 2,4,5trimethoxyphenyl group are almost coplanar with the ring [deviations of the C atoms = 0.017 (2) and À0.025 (2) Å , respectively], whereas the meta-methoxy group deviates slightly [C-atom displacement = 0.162 (2) Å ]. Both the orthoand para-nitro groups are close to being coplanar with their attached ring [dihedral angles = 7.81 (12) and 8.56 (11) , respectively]. An intramolecular N-HÁ Á ÁO hydrogen bond generates an S(6) ring motif. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds involving the same H atom as the intramolecular bond generate R 2 2 (12) loops. The dimers are linked by weak C-HÁ Á ÁO interactions into sheets parallel to the (104) plane and the sheets are stacked byinteractions, with a centroid-centroid distance of 3.5974 (14) Å .
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PLATON (Spek, 2009) and publCIF (Westrip, 2010). Hydrazones are known to be bioactive compounds with various biological properties such as antibacterial, antifungal, antitumor, anti-inflammatory and antioxidant activities (Angelusiu et al., 2010;Cui et al., 2010;Gokce et al., 2009 andWang et al., 2009). Diaryl hydrazones were reported to be multifunctional inhibitors of amyloid self-assembly which is related to aging-related diseases such as Alzheimer's disease (Török et al., 2013). With our ongoing research on bioactive diaryl hydrazones, the title compound (I) was synthesized in order to study and compare its biological activity with the other related compounds (Fun et al., 2011;2012). Our antioxidant activity evaluation of (I) by DPPH scavenging (Molyneux, 2004) found that (I) possesses antioxidant activity with 89.04% inhibition. Furthermore its anti-Alzheimer activity is under investigation and will be reported elsewhere. Herein we report the synthesis and crystal structure of (I).
In Fig. 1, the molecular structure of (I), C 16 H 16 N 4 O 7 , is essentially planar with the dihedral angle between the two substituted benzene rings being 3.15 (11) Table 1) generates an S(6) ring motif.

Experimental
The title compound (I) was synthesized by dissolving 2,4-dinitrophenylhydrazine (0.40 g, 2 mmol) in ethanol (10.00 ml) and H 2 SO 4 (conc.) (0.50 ml) was slowly added with stirring. The solution of 2,4,5-trimethoxybenzaldehyde (0.40 g, 2 mmol) in ethanol (20.00 ml) was then added to the solution with continuous stirring for 1 hr, yielding a red solid which was filtered off and washed with methanol. Red needles of the title compound were recrystalized from ethanol solution by slow evaporation of the solvent at room temperature over several days, Mp. 528-529 K.

Refinement
The hydrazine H atom was located from a difference Fourier map and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for CH and aromatic, and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups.

Figure 1
The molecular structure of (I), showing 60% probability displacement ellipsoids. The intramolecular N-H···O hydrogen bond is shown as a dashed line.       (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.