organic compounds
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The crystal structure of the title co-crystal, 2C6H7N3O·C6H10O4, is a second polymorph, designated form II, of the co-crystal formed between the two molecules [Lemmerer et al. (2011). CrystEngComm, 13, 55–59]. The asymmetric unit comprises one molecule of nicotinic acid hydrazide, and one half-molecule of adipic acid (the entire molecule is completed by the application of a centre of inversion). In the crystal, molecules assemble into a three-dimensional network of hydrogen bonds, formed by three N—HO hydrogen bonds and one O—HN hydrogen bond. The O—HN hydrogen bond formed between the carboxyl group and the pyridine ring is supported by a C—HO hydrogen bond.