Form II of adipic acid–nicotinohydrazide (1/2)

The crystal structure of the title co-crystal, 2C(6)H(7)N(3)O·C(6)H(10)O(4), 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—H⋯O hydrogen bonds and one O—H⋯N hydrogen bond. The O—H⋯N hydrogen bond formed between the carboxyl group and the pyridine ring is supported by a C—H⋯O hydrogen bond.