2,2′-[(1E,1′E)-2,2′-(2,5-Dibutoxy-1,4-phenylene)bis(ethene-2,1-diyl)]dipyridine

The centrosymmetric title molecule, C28H32N2O2, has a central benzene ring subsituted in the 1- and 4-positions by (ethene-2,1-diyl)pyridine groups, and in the 2- and 5-positions by butoxy groups. The whole molecule is X-shaped and relatively flat, the dihedral angle between the pyridine and the central benzene ring being 11.29 (10)°. In the crystal, neighboring molecules are linked by weak C—H⋯N interactions, forming a two-dimensional undulating network.

The centrosymmetric title molecule, C 28 H 32 N 2 O 2 , has a central benzene ring subsituted in the 1-and 4-positions by (ethene-2,1-diyl)pyridine groups, and in the 2-and 5-positions by butoxy groups. The whole molecule is X-shaped and relatively flat, the dihedral angle between the pyridine and the central benzene ring being 11.29 (10) . In the crystal, neighboring molecules are linked by weak C-HÁ Á ÁN interactions, forming a two-dimensional undulating network.
In the title molecule ( Fig. 1), which is centrosymmetric, there are two pyridine rings and a central benzene ring. The dihedral angle between the pyridine and the central benzene ring is 11.29 (10) °.
In the crystal structure of the title compound there exist C5-H5···N1 i interactions between neighboring molecules [see  Table 1]. This leads to the formation of a two-dimensional network lieing parallel to the bc-plane.

Experimental
The title compound was prepared by firstly placing t-BuOK (8.98 g, 0.080 mol) in a dry motar and milling it to give very small particles. Then 2,5-Dibutoxy-1,4-bis(triphenylphosphonium)benzene dischloride (8.45 g, 0.010 mol) and picolinaldehyde (4.28 g, 0.040 mol) were added. The mixture was then milled vigorously for about 10 min. After the reaction was completed (monitored by TLC), the mixture was dispersed in 50 ml of H 2 O. The solution was extracted three times with 50 ml dichloromethane. The dichloromethane solution was dried for 12 h and concentrated. The concentrated solution was passed over a silica gel column and eluted with peroleum ether/ethyl acetate (8:1). By slow evaporation of the solvent yellow block-like crystals were obtained in 75% yield.

Refinement
The H-atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms: C-H = 0.93, 0.96 and 0.97 Å for CH, CH 3 and CH 2 H-atoms, respectively, with U iso (H) = k × U eq (parent C-atom), where k = 1.2 for CH and CH 2 H-atoms and = 1.5 for CH 3 H-atoms.

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.
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 Rfactors(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.