Eight new phenylisoxazole isoniazid derivatives, 3-(2'-fluorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (1), 3-(2'-methoxyphenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (2), 3-(2'-chlorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (3), 3-(3'-clorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (4), 3-(4'-bromophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (5), 5-(4'-methoxiphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (6), 5-(4'-methylphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (7), and 5-(4'-clorophenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (8), have been synthesized and characterized by FT-IR, 1H-NMR, 13C-NMR, and mass spectral data. The 2D NMR (1H-1H NOESY) analysis of 1 and 2 confirmed that these compounds in acetone-d6 are in the trans(E) isomeric form. This evidence is supported by computational calculations which w...