1-{[4′-(1H-1,2,4-Triazol-2-ium-1-ylmeth­yl)biphenyl-4-yl]meth­yl}-1H-1,2,4-triazol-2-ium bis­(3-carb­oxy-5-iodo­benzoate)–5-iodo­benzene-3,5-dicarb­oxy­lic acid–water (1/2/2)

The neutral carb­oxy­lic acid mol­ecule and the carboxyl­ate anion in the title compound, C(18)H(18)N(6) (2+)·2C(8)H(4)IO(4) (−)·2C(8)H(5)IO(4)·2H(2)O, are both nearly planar (r.m.s. deviations = 0.034 and 0.045 Å, respectively). In the cation, the mid-point of the C—C bond linking the two benzene rings lies on a center of inversion, and the triazole ring is approximately perpendicular to the adjacent benzene ring [dihedral angle = 83.2 (3)°]. In the crystal, the cations, anions, carb­oxy­lic acid and lattice water mol­ecules are linked by N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds, generating a ribbon running along [1-10]. The crystal studied was a non-merohedral twin with the components in a 51.2 (1):48.8 (1) ratio.