Synthesis and characterisation of a calix(4)arene Schiff base and its complexation studies with transition metal ions

The synthesis and complexation of the Schiff base 5,17-N,N'-bis(salicylidene)-25,26,27,28-tetrahydroxy-5,17-diamino-11,23-dinitrocalix(4)arene (calixarene Schiff base) derived from aminocalix(4)arene and salicyladehyde is described. The aminocalix(4)arene was prepared by the reduction of tetranitrocalix(4)arene which was synthesised by condensing p-nitrophenol with formaldehyde in xylene using HCl as catalyst. The complexes of the Schiff base with the metal ions Cu(II), Co(II), Ni(II) and Mn(II) were prepared and characterised by elemental analyses, IR, H-1 NMR and mass spectrometry. The results of preliminary studies on the extraction of these metals with the Schiff base are also reported.