2-Hydroxy-1-naphthaldehyde-derived Schiff bases: synthesis, characterization, and structure

Abstract

Four Schiff base molecules were synthesized from the condensation of 2-hydroxy-1-naphthaldehyde with various amines having additional ligating centers, and the resulting products were characterized by analytical and spectral methods, and also by single crystal X-ray diffraction. 2-(β-Naphthalideneamino)-2-methyl-1-propanol, 1, is orthorhombic, P2₁2₁2₁, a = 9.918(1), b = 12.629(1), c = 10.416(1) Å. 2-(β-Naphthalideneamino)-2-hydroxymethyl-1-propanol, 2, is monoclinic, P2₁/c, a = 14.522(3), b = 9.723(2), c = 9.534(9) Å, β = 107.75(4)°. 2-(β-Naphthalideneamino)-2-hydroxymethyl-1,3-propanediol, 3, is monoclinic, P2₁/c, a = 20.981(9), b = 5.943(3), c = 10.549(5) 197;, = 91.23(3)°. 2-(α-Naphthalideneamino)-pyridine, 4, is monoclinic, P2₁/c, a = 5.804(4), b = 17.363(2), c = 24.032(11) Å, β= 92.03(5)°. The molecular structures of these were found to be in extended conformation where the aromatic moiety is coplanar with that of the imine bond and the imine bond exhibited trans-geometry. The naphthyl moiety in each of these molecules is stabilized in quinoid form in the solid state. Interesting lattice structures were noticed owing to intermolecular interactions.