Resacetophenone isoniazid hydrazone

N'-(2,4-Dihydroxy-α-methylbenzylidene)isonicotinic hydrazide

N'-[1-(2,4-Dihydroxyphenyl)ethylidene]isonicotinic hydrazide

N'-[1-(2,4-Dihydroxyphenyl)ethylidene]-4-pyridinecarbohydrazide

N'-(2,4-Dihydroxy-α-methylbenzylidene)-4-pyridinecarbohydrazide