In the structure of the title compound, C(10)H(10)N(2) (2+)·2ClO(4) (-)·4C(7)H(7)NO(2)·2C(10)H(8)N(2)·2H(2)O, the 4,4'-bipyridinium cation has a crystallographically imposed centre of symmetry. The cation is linked by N-H⋯N hydrogen bonds to adjacent 4,4'-bipyridine mol-ecules, which in turn inter-act via O-H⋯N hydrogen bonds with 4-amino-benzoic acid mol-ecules, forming chains running parallel to [30]. The chains are further connected into a three-dimensional network by N-H⋯O and O-H⋯O hydrogen-bonding inter-actions involving the perchlorate anion, the water mol-ecules and the 4-amino-benzoic acid mol-ecules. In addition, π-π stacking inter-actions with centroid-centroid distances ranging from 3.663 (6) to 3.695 (6) Å are present. The O atoms of the perchlorate anion are disordered over two sets of positions, with refined site occupancies of 0.724 (9) and 0.276 (9).
In the structure of the title compound, C(10)H(10)N(2) (2+)·2ClO(4) (-)·4C(7)H(7)n class="Chemical">NO(2)·2C(10)H(8)N(2)·2H(2)O, the 4,4'-bipyridinium cation has a crystallographically imposed centre of symmetry. The cation is linked by N-H⋯Nhydrogen bonds to adjacent 4,4'-bipyridine mol-ecules, which in turn inter-act via O-H⋯Nhydrogen bonds with 4-amino-benzoic acid mol-ecules, forming chains running parallel to [30]. The chains are further connected into a three-dimensional network by N-H⋯O and O-H⋯O hydrogen-bonding inter-actions involving the perchlorate anion, the water mol-ecules and the 4-amino-benzoic acid mol-ecules. In addition, π-π stacking inter-actions with centroid-centroid distances ranging from 3.663 (6) to 3.695 (6) Å are present. The O atoms of the perchlorate anion are disordered over two sets of positions, with refined site occupancies of 0.724 (9) and 0.276 (9).