SS-NMR applied to the characterization of polymers and gem-diol compounds

JUAN MANUEL LÁZARO MARTÍNEZ; GRACIELA YOLANDA BULDAIN; DANIEL VEGA; GUSTAVO ALBERTO MONTI; ANA KARINA CHATTAH

Rosario

Workshop; Workshop Frontiers in Magnetic Resonance, from Materials to Biological Systems; 2013

Instituto de Biología Molecular y Celular de Rosario

Macromolecular chemistry has become of great interest to yield processable materials with unique and valuable properties. Among them, polymer networks offer new possibilities to scientists for the creation of artificial materials. In particular, incorporating coordination complexes into polymeric architectures opens up the possibility of imparting the physicochemical properties of both partners to the resulting material. In particular, metallo-hydrogels containing copper or cobalt ions are particularly useful due to the catalytic activity of these complexes.1 In this field, the synthesis of new class of ligands, such as gem-diolate molecules, is a growing research area for the obtention of novel polymers. For instance, Perlepes et al. have studied the employment of di-2-pyridyl ketone, (py)2CO, as an organic ligand for the synthesis of high nuclearity metal complexes.2 However, the gem-diol form for (py)2CO exist only in the respective metal complex, since these compounds are rarely stable (and only in aqueous solution). In particular, our group has found that the 2-formylimidazole hydrate is a stable crystalline substance because, in order to revert to the aldehyde-form, a water molecule must be left out, and this is difficult by the electron-withdrawing character of the imidazolium cation (Fig. 1).3 In this work, we describe structural, dynamic homogeneity and the metal ion uptake properties from different hydrogels containing carboxylic acid and heterocyclic azole groups (imidazole, triazole and pyrazole) and in three synthetic variants of poly(ethyleneimine) polymers with different molecular weights (22, 87 and 217 kDa). In addition, the existence and stability of the aldehyde-hydrate form of some pyridine and imidazole carboxaldehyde derivatives (Fig. 1) were studied using solution- and solid-state NMR together with single-crystal X-ray crystallography experiments. REFERENCES 1.Lázaro Martínez et al. Appl. Catal.,B 2008, 82, 273; J. Mol. Catal. A: Chem. 2011, 339, 43 & Appl. Catal. A General 2013, 467, 342. 2. Perlepes et al. Dalton Trans., 2008, 5537 & Polyhedron 2013, in press. 3.Lázaro Martínez et al. J. Org. Chem. 2010, 75, 3208. ACKNOWLEDGEMENTS CONICET, ANCYPT, UBACyT