N-(4-nitrobenzylidene)-N'-phenylhydrazine.

Molecules of the title compound (alternative name: p-nitrobenzaldehyde phenylhydrazone), C(13)H(11)N(3)O(2), adopt an E configuration about the azomethine C=N double bond. Molecules are approximately planar and the dihedral angle between the planes of the phenyl rings is 11.62 (9) degrees. Hydrogen bonding links molecules related by 4(2) screw axes to form helices with a pitch of 7.7186 (8) A.

N-(4-Methoxybenzylidene)-N'-(2-pyridyl)hydrazine.

Molecules of the title compound (alternative name p-methoxybenzaldehyde 2-pyridylhydrazone), C(13)H(13)N(3)O, adopt an E configuration about the azomethine C=N double bond. Molecules are almost planar, the dihedral angle between the pyridine and methoxyphenyl rings being only 6.19 (12) degrees. Pairwise N-H.N hydrogen bonds [R(2)(2)(8) in graph-set notation] link centrosymmetrically related molecules into discrete pairs.