Bis(pyridinium) Pamoate

Attempted crystallization of pamoic acid from its solution in pyridine instead produced the crystalline title compound, bis(pyridinium) 4,4'-methylenebis(3-hydroxy-2-naphthalenecarboxylate), 2C₅H₆N⁺.C₂₃H₁₄O₆^2-. In this structure, intramolecular hydrogen bonding involves hydroxyl O atoms as donors and carboxylate O atoms as acceptors, while intermolecular hydrogen bonds involve N atoms as donors and carboxylate O atoms as acceptors. Each N atom and each O atom participates in a strong hydrogen bond. The H atoms involved in hydrogen bonding are ordered.

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