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

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—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.

N′-Cyclo­dodecyl­idene­pyridine-4-carbohydrazide

The title compound, C₁₈H₂₇N₃O, is a derivative of the anti­tuberculosis drug isoniazid (systematic name: pyridine-4-carbohydrazidei). The crystal structure consists of repeating C(4) chains along the b axis, formed by N—H...O hydrogen bonds with adjacent amide functional groups that are related by a b-glide plane. The cyclo­dodecyl ring has the same approximately `square' conformation, as seen in the parent hydro­carbon cyclo­dodecane.

N′-Cyclo­pentyl­idene­pyridine-4-carbo­hydrazide

The title compound, C₁₁H₁₃N₃O, is a derivative of the anti­tuberculosis drug isoniazid [systematic name: pyridine-4-carbohydrazide]. The crystal structure consists of repeating hydrogen-bonded chains parallel to the b axis. Adjacent mol­ecules in the chains are linked by bifurcated N—H...(O,N) hydrogen bonds, which form an R₁²(5) ring motif.