TRANSITION-METAL COMPLEXES OF POLYMERIC AMINO LIGANDS DERIVED FROM TRIETHYLENEGLYCOL DIMETHACRYLATE CROSS-LINKED POLYACRYLAMIDES

Amino functions were incorporated into triethyleneglycol dimethacrylat e (TEGDMA)-crosslinked (2-20 mol %) polyacrylamides by transamidation with ethylenediamine. The complexation of these polymeric ligands with the amino function in different structural environments was investiga ted toward Cr(III), Mn(II), Fe(III), Cu(II), Cd(II), and Pb(II) ions. The metal ion intake decreased with the extent of the crosslinking and followed the order Cu(II) > Cr(III) > Mn(II) > Fe(III) > Pb(II) > Cd( II). The pH dependence of complexation and distribution coefficient; t ime course and kinetics of complexation; swelling properties of the un complexed and complexed resins in water; recyclability; infrared (IR) spectra; electron paramagnetic resonance; ultraviolet visibility; magn etic susceptibility; and thermogravimetric and scanning electron micro scopy studies were carried out. The kinetics of complexation was found to be first order. The swelling of the complexed resins is lower than that of the uncomplexed resins. Complexation resulted in the lowering of the IR absorption of the amino ligands. The IR data of the TEGDMA- crosslinked polyacrylamide amine and the corresponding Cr(III) complex reveals that the metal is coordinated with the ligand through the ami no nitrogen. The SO4= is also coordinated. The number of coordinated n itrogen atoms varies as the hydrophilicity and flexibility of the poly mer change with the crosslinking. Thus spectral and magnetic studies s uggest a distorted octahedral geometry for Cu(II) complexes, octahedra l geometry of the d(3) system for Cr(III), and d(5) high-spin octahedr al geometry for Fe(III) and Mn(II) complexes. The thermal stabilities of the complexed resins increase with increase in the metal content. S urface morphology of the polymeric ligand changes on complexation. (C) 1996 John Wiley & Sons, Inc.