1-(2,4-Dinitrophenyl)-2-[(E)-(3,4,5-trimethoxybenzylidene)]hydrazine

Molecules of the title compound, C16H16N4O7, are not planar with a dihedral angle of 5.50 (11)° between the substituted benzene rings. The two meta-methoxy groups of the 3,4,5-trimethoxybenzene moiety lie in the plane of the attached ring [Cmethyl–O–C–C torsion angles −0.1 (4)° and −3.7 (3)°] while the para-methoxy substituent lies out of the plane [Cmethyl—O—C—C, −86.0 (3)°]. An intramolecular N—H⋯O hydrogen bond involving the 2-nitro substituent generates an S(6) ring motif. In the crystal structure, molecules are linked by weak C—H⋯O interactions into screw chains, that are arranged into a sheet parallel to the bc plane. These sheets are connected by π–π stacking interactions between the nitro and methoxy substituted aromatic rings with a centroid–centroid separation of 3.9420 (13) Å. C—H⋯π contacts further stabilize the two-dimensional network.

Molecules of the title compound, C 16 H 16 N 4 O 7 , are not planar with a dihedral angle of 5.50 (11) between the substituted benzene rings. The two meta-methoxy groups of the 3,4,5trimethoxybenzene moiety lie in the plane of the attached ring [C methyl -O-C-C torsion angles À0.1 (4) and À3.7 (3) ] while the para-methoxy substituent lies out of the plane [C methyl -O-C-C, À86.0 (3) ]. An intramolecular N-HÁ Á ÁO hydrogen bond involving the 2-nitro substituent generates an S(6) ring motif. In the crystal structure, molecules are linked by weak C-HÁ Á ÁO interactions into screw chains, that are arranged into a sheet parallel to the bc plane. These sheets are connected bystacking interactions between the nitro and methoxy substituted aromatic rings with a centroidcentroid separation of 3.9420 (13) Å . C-HÁ Á Á contacts further stabilize the two-dimensional network.
In previous works, we synthesized a number of hydrazone derivatives from the reaction of 2,4-dinitrophenylhydrazine and various substituted aldehydes (Fun et al., 2011(Fun et al., , 2012(Fun et al., and 2013. The title hydrazone (I) was again synthesized using 2,4-dinitrophenylhydrazine but with 3,4,5-trimethoxybenzaldehyde as the aldehyde. Our evaluation of the antioxidant activity of (I) by the DPPH free radical scavenging method [DPPH = 2,2-diphenyl-1-picrylhydrazyl] (Molyneux, 2004) showed that it displays weak antioxidant activity with 17.6% inhibition. This further confirms observations from previous works (Fun et al., 2011(Fun et al., , 2012(Fun et al., and 2013 that the antioxidant ability of such compounds is controlled by the number and substitution pattern of the methoxy substituents. Herein we report the synthesis and crystal structure of (I).

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.) (98 %, 0.50 ml) was added slowly with stirring. A solution of 3,4,5-trimethoxybenzaldehyde (0.40 g, 2 mmol) in ethanol (20.00 ml) was then added to the solution with continuous stirring for 1 hr, yielding an orange solid supplementary materials sup-2 Acta Cryst. (2014). E70, o188-o189 which was filtered off and washed with methanol. Orange block-shaped single crystals of the title compound suitable for X-ray structure determination were recrystallized from acetone by slow evaporation of the solvent at room temperature over a few weeks, Mp. 496-497 K.

Refinement
The hydrazine H atom was located from a difference Fourier map and refined freely. 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 40% probability displacement ellipsoids and the atom-numbering scheme. An intramolecular N-H···O hydrogen bond is shown as a dashed line.  The crystal packing of (I) viewed along the a axis. Hydrogen bonds are shown as dashed lines.

Figure 3
The π···π stacking interaction between the two substituted benzene rings. H atoms were omitted for clarity.  (Cosier & Glazer, 1986) operating at 120.0 (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.