title: 4,4'-Bipyridine-2-hydroxy-propane-1,2,3-tricarboxylic acid (3/2).
abstract: The combination of 2-hydroxy-propane-1,2,3-tricarboxylic acid (H(3)hypta, also called citric acid) and 4,4'-bipyridine (4,4'-bipy) in a 1:1.5 molar ratio leads to the formation of the title mol-ecular cocrystal, 1.5C(10)H(8)N(2)·C(6)H(8)O(7). The asymmetric unit contains one and a half 4,4'-bipy units, with one lying across a centre of inversion, and one H(3)hypta mol-ecule. The significant differences in the C-O bond distances support the existence of the un-ionized acid mol-ecule and confirm the formation of a cocrystal. There are π-π and C-H⋯π stacking inter-actions between the aromatic rings of 4,4'-bipy [with inter-planar distances of 3.7739 (8) and 3.7970 (8) Å] and between CH groups of H(3)hypta [with an H⋯π distance of 2.63 Å]. In the crystal structure, intermolecular O-H⋯N hydrogen bonds occur and an O-H⋯O hydrogen bond occurs within the citric acid moiety.
authors.forename: Janet
authors.initials: J
authors.lastname: Soleimannejad
authors.forename: Hossein
authors.initials: H
authors.lastname: Aghabozorg
authors.forename: Shokoh
authors.initials: S
authors.lastname: Najafi
authors.forename: Mina
authors.initials: M
authors.lastname: Nasibipour
authors.forename: Jafar
authors.initials: J
authors.lastname: Attar Gharamaleki