Dicarboxyamylose and dicarboxycellulose,stereoregular polyelectrolytes: physicochemical characterization and interaction with divalent cations

2,3-Dicarboxyamylose (DCA) and 2,3-dicarboxycellulose (DCC) have been obtained by splitting with periodate of all the C(2)C(3) bonds of amylose and cellulose, and further oxidation (with chlorite) of the corresponding polydialdehydes. Small, but reproducible, differences of ¹³C chemical shifts in dicate that DCA and DCC retained the different configuration at C-1 of the original polysaccharides, therefore being stereoisomers. The potentiometric and conductimetric titration curves of DCA and DCC and the pH-dependence of their ¹H n.m.r. spectra are those of typical polydicarboxylates. Interaction of DCA and DCC (Na salts) with divalent cations is clearly indicated by inflexions in conductimetric titration curves with Ca²⁺, Mg²⁺, Cu²⁺ and Fe²⁺, and by variation in specific optical rotation.