1,4-Bis(2-pyridylmethoxy)benzene

In the title compound, C18H16N2O2, the phenylene ring is located on inversion center. The pyridyl ring makes a dihedral angle of 39.9 (1)° with the phenylene ring. In the crystal, adjacent molecules are linked by intermolecular C—H⋯N hydrogen bonds, forming a linear chain along the a axis.

In the title compound, C 18 H 16 N 2 O 2 , the phenylene ring is located on inversion center. The pyridyl ring makes a dihedral angle of 39.9 (1) with the phenylene ring. In the crystal, adjacent molecules are linked by intermolecular C-HÁ Á ÁN hydrogen bonds, forming a linear chain along the a axis.

The authors thank the Specialized Research Funds for Technological
Innovative Talent in Harbin (RC2009XK018007) and Heilongjiang University for supporting this study.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: NG2637).

S1. Comment
The bipyridyl ligand is generally used as bridge units to construct metal-organic framework. Hartshorn's group have reported the syntheses of the silver and palladium complexes with the 1,4-bis(2-pyridylmethoxy)benzene ligand, which assemble into one-dimensional zigzag chain in the former and an M 2 L 2 26-membered macrocycle in the latter (Hartshorn et al., 1998). Oh's group have investeigated how metal-ligand stoichiometry can be used to influence the formation of polymeric structures, in which they reacted silver salts with the 1,4-bis(2-pyridylmethoxy)benzene ligand in 1:1 ratio to form one-dimensional zigzag chain and in 1:2 ratio to yield a two-dimensional porous network. Herein we synthesized the same ligand and hoped to obtain the fluorescent material by reacting the ligand with d 10 metal, but we get a lot of crystals of the ligand itself and report its crystal structure here.
The X-ray single-crystal analysis of the title compound shows that the 1,4-bis(2-pyridylmethoxy)benzene molecule is centrosymmetric. The planes of two terminal pyridyl groups are parallel and make dihedral angles of 39.9 (1) ° with the plane of the central benzene ring (Figure 1). In the crystal structure, the 1,4-bis(2-pyridylmethoxy)benzene molecules are linked by intermolecular C-H···N hydrogen bonds into one dimensional chains along a axis direction (Table 1, Figure   2).

S2. Experimental
The 1,4-bis(2-pyridylmethoxy)benzene was synthesized by the reaction of p-benzenediol and 2-chloromethylpyridine hydrochloride under nitrogen atmosphere and alkaline condition (Gao et al., 2004;Gao et al., 2006). A solution of Zn(NO 3 ) 2 .6H 2 O (0.3 g, 1 mol) in water (5 ml) was dropped slowly into a methanol solution (5 mL) of 1,4-bis(2-pyridylmethoxy)benzene (1.46 g, 5 mmol) to give a clear solution. Colourless nod-shaped crystals of scheme were obtained by slow evaporation of the clear solution after four days.  The molecular structure of the title compound, showing displacement ellipsoids at the 30% probability level for non-H atoms.

Figure 2
A partial packing view, showing the one-dimensional hydrogen bonding chain. Dashed lines indicate the hydrogenbonding interactions and no involving H atoms have been omitted. 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 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.