The asymmetric unit of the title 1:1 co-crystal, C 10 H 8 N 2 ·C 10 H 10 O 4 , consists of one half-molecule each of 4,4′-bipyridine and 1,4-phenylenediacetic acid: the complete molecules are generated by crystallographic inversion centres. The dihedral angle between the –CO 2 H group and the benzene ring in the diacid is 73.02 (7)°. In the crystal, the components are linked by O—H...N hydrogen bonds, generating [1-2-1] chains of alternating amine and carboxylic acid molecules. The chains are cross-linked by C—H...O interactions. This structure was previously incorrectly described as a (C 10 H 10 N 2 ) 2+ ·(C 10 H 8 O 4 ) 2− molecular salt [Jia et al. (2009). Acta Cryst. E 65 , o2490–o2490].
Paul, R., & Bora, S. J. (2015). Redetermined structure of 4,4′-bipyridine-1,4-phenylenediacetic acid (1/1) co-crystal. Acta Crystallographica Section E: Crystallographic Communications, 71, o799–o800. https://doi.org/10.1107/S2056989015017569