Solid-state NMR and thermal analysis in copper polymer complexes

JUAN MANUEL LÁZARO MARTÍNEZ; ANA KARINA CHATTAH; GUSTAVO ALBERTO MONTI; MARÍA FLORENCIA LEAL DENIS; VIVIANA CAMPO DALL´ORTO; GRACIELA YOLANDA BULDAIN

Mainz, Alemania

Simposio; Frontiers in Polymer Science - International Symposium Celebrating the 50th Anniversary of the Journal Polymer; 2009

Elsevier

Two particular interesting groups of functionalized polymeric materials are the polyampholytes and polyelectrolytes [1-4].We have recently syntethized new polymeric materials with the characteristics of polyelectrolyte (Poly(EGDE-MAA) = A) or polyampholyte (Poly(EGDE-MAA-IM) = B) and their copper(II) complexes, respectively [5-7]. Remarkably, the Cu(II)-polyampholyte acts as an efficient heterogeneous catalyst for H2O2 activation and the degradation of Methyl Orange [8]. The coordination behavior of the carboxylic acid of the MAA, compared to that provided by the imidazole ring, was studied through solid-state NMR and changes in the FTIR spectra.It was possible to observe that the carbon signal of the carboxylic acid disappeared in the A and B materials in the 13C CP-MAS spectra at 1 and 63 mg of Cu(II) per gram of material, respectively, in agreement with the FTIR results [7]. In the B complexes, a competence for the complexation through imidazole and MAA occurs; then, when the imidazole is saturated, the complexation takes place preferentially through MAA, as concluded from the FTIR and solid-state NMR results. However, the DSC studies determined the presence of different molecular mobility regions within both A and B polymers, in agreement with the double decay observed in the experiments. On the other hand, the 2D WISE-NMR experiments together with the relaxation experiments, allow us to conclude that although the relaxation behavior was modified, the paramagnetic ion does not change the structure of the polymer substantially [7]. Finally, TGA gives evidence that the B material bearing the imidazole ring presented a more thermal stability than A, associated with the presence of this ligand [9]. Then, the B complexes have the property of coordinating higher amounts of Cu(II), which explains the lower thermal stability in those materials due to changes in the electronic density in the polymeric matrix.