Synthesis, characterisation and crystal structures of Schiff bases from the reaction of 4,6-O-ethylidene-β-D-glucopyranosylamine with substituted salicylaldehydes

Abstract

Multiple chemical modifications were carried out on D-glucose to result in the corresponding Schiff bases. Such modifications performed on D-glucose not only helped in increasing the solubility of the products in nonaqueous solvents, but also restricted the anomerisation of the saccharide moiety in solution. NMR study of the products revealed the presence of the β-anomeric form of the saccharide moiety in Me₂SO solution. All the compounds were characterised by analytical and spectral methods. The literature is devoid of any crystal structures of saccharide-Schiff base combinations of the type reported in this paper. The crystal structures of these molecules exhibited a tridentate, ONO binding core. These studies further revealed that the compounds in the solid state were in the β-D-pyranose form with the ⁴C₁ chair conformation. The compounds exhibited interesting lattice structures assisted through weak interactions of the type O-H-O and C-H-O. The lattice structure of one of these compounds exhibited channels filled with chloroform molecules.