Hemi(4,4'-bipyridinium) hexa-fluorido-phosphate bis-(4-amino-benzoic acid) 4,4'-bipyridine monohydrate.

In the title compound, 0.5C(10)H(10)N(2) (2+)·PF(6) (-)·C(10)H(8)N(2)·2C(7)H(7)NO(2)·H(2)O, the cation is located on a center of symmetry. The crystal structure is determined by a complex three-dimensional network of inter-molecular O-H⋯O, O-H⋯N, N-H⋯N and N-H⋯F hydrogen bonds. π-π stacking inter-actions between neighboring pyridyl rings are also present; the centroid-centroid distance is 3.643 (5) Å. The hexa-fluoridophosphate anion is disordered over two positions with site-occupancy factors of ca 0.6 and 0.4.