1,3-Di-4-pyridylpropane–4,4′-oxydibenzoic acid (1/1)

The hydrothermal reaction of Cd(NO3)2·4H2O, 1,3-di-4-pyridylpropane (BPP) and 4,4′-oxydibenzoic acid (OBA) led to the formation of the title compound, C13H14N2·C14H10O5. The asymmetric unit consists of one molecule of OBA and one of BPP. In the OBA molecule, one COOH group is nearly planar with its attached benzene ring [dihedral angle = 0.9 (1)°], while the other COOH group is slightly twisted with a dihedral angle of 10.8 (3)°. The carboxyl groups form strong intermolecular O—H⋯N hydrogen bonds with N atoms of the pyridine rings in BPP, linking the molecules into zigzag chains.

The hydrothermal reaction of Cd(NO 3 ) 2 Á4H 2 O, 1,3-di-4pyridylpropane (BPP) and 4,4 0 -oxydibenzoic acid (OBA) led to the formation of the title compound, C 13 H 14 N 2 ÁC 14 H 10 O 5 . The asymmetric unit consists of one molecule of OBA and one of BPP. In the OBA molecule, one COOH group is nearly planar with its attached benzene ring [dihedral angle = 0.9 (1) ], while the other COOH group is slightly twisted with a dihedral angle of 10.8 (3) . The carboxyl groups form strong intermolecular O-HÁ Á ÁN hydrogen bonds with N atoms of the pyridine rings in BPP, linking the molecules into zigzag chains.
there has been a growing interest in metal-organic frameworks based on 1,3-di-4-pyridylpropane and 4,4'-oxydibenzoic acid ligands Luan et al., 2005;Belcher et al., 2002;Han et al., 2007;Nguyen et al., 2006). Recently, we have focused on preparing metal-organic frameworks containing such organic ligands and metal ions. During the process, a new cocrystal of 1,3-di-4-pyridylpropane and 4,4'-oxydibenzoic acid was obtained which assembled by H-bondin and we report its synthesis and crystal structure here. The structures of some similar molecular materials have been reported (Dai et al., 2005;Lee et al., 2003;Ma et al., 2006;Wang et al., 2008;Hou et al., 2008;Najafpour et al., 2008). An independent study of (I) has also been published .
Intermolecular C-H···O hydrogen bonds may be effective in the stabilization of the crystal structure.
After slow cooling to room temperature, the block-shaped colourless crystalline product was filtered, washed with distilled water, and dried at ambient temperature. The crystal used for data collection was obtained directly from the sample that was washed and dried without further re-crystallization.

Refinement
The C-bound H atoms were positioned geometrically with C-H = 0.93-0.97 Å, and allowed to ride on their parent atoms with U iso (H) = 1.2 U eq (C). The H atoms on oxygen atoms of carboxylic acid groups were found in a difference map and refined with a riding model with O-H = 0.82 Å and U iso (H) = 1.2 U eq (C).