1,1′-Methylenebis{4-[(E)-2-(pyridin-4-yl)ethenyl]pyridinium} dibromide dihydrate

Cations of the title compound interact via π–π interactions and hydrogen bond with water to form a zigzag ribbon.

The chevron-shaped cations of the title hydrated salt, C 25 H 22 N 4 2+ Á2Br À Á2H 2 O, are arranged in back-to-back alternating directions to form a zigzag ribbon propagating along the [010] direction. Intermolecular interactions comprising these ribbons areinteractions between the pyridinium and adjacent pyridyl rings, as well as O-HÁ Á ÁO hydrogen bonding between water molecules and two adjacent pyridyl N atoms. Half of the cation is generated by the mirror plane. The water O atoms, the central C atom and one Br atom are located on this mirror plane while the other Br atom is on a twofold screw axis.

Synthesis and crystallization
The title compound was synthesized according to published procedures (Blanco et al., 2009). Colorless plates were grown from liquid diffusion of tetrahydrofuran into a dimethylformamide solution of the pyridinium bromide salt.

Figure 3
Ellipsoid (50%) representation of ribbons of cations with bromide ions (brown) and water molecules positioned between them. Ellipsoids at 50% with disorder omitted for clarity.

Figure 1
Ellipsoid (50%) representation of the title complex with disorder omitted for clarity.

Figure 2
Zigzag ribbons composed of back-to-back chevron-shaped cations of the title complex. The distance between N2 and H1D( 3 2 À x, 1 À y, 1 2 + z) is shown. Ellipsoids at 50% with disorder, bromide ions and some water molecules omitted for clarity. our attempts to refine the structure to achieve equal occupancies led to a drastic worsening of R1 and wR2 values.

data-1
IUCrData ( Special details 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.