The aldoximes C11H9NO (I) and C15H11NO (II), synthesized in ca 90% yield, by treatment of 1-naphthaldehyde or phenanthrene-9-carbaldehyde, respectively, with hydroxyl-amine hydro-chloride and sodium carbonate, have been characterized by IR, 1H, 13C and DEPT-135 NMR spectroscopies, and also by single-crystal X-ray diffraction analysis. The mol-ecules of (I) and (II) are conformationally similar, with the aldoxime substituent groups lying outside the planes of the naphthalene or phenanthrene rings, forming dihedral angles with them of 23.9 (4) and 27.9 (6)°, respectively. The crystal structures of both (I) and (II) are similar with a single inter-molecular O-H⋯N hydrogen-bonding inter-action, giving rise to the formation of one-dimensional polymeric chains extending along the 21 (b) screw axes in each.
Keywords: E-aldoximes; aromatic aldehydes; crystal structure; hydrogen bonding.