Formation of Copper(II) Complexes with Low- and High-Methoxylated Pectins Modified with Salicylic and Anthranylic Acids

Low- and high-methoxylated pectins were synthesized and modified with anthranilic and salicylic acids to obtain effective polymeric ligands. On their basis, new copper(II) metal-polymer complexes were obtained, their composition was determined, stability constants and thermodynamic characteristics of the complex formation process were calculated. The efficiency of the metal binding to the polymer ligand depends mainly on the degree of pectin methoxylation, the acidity of the medium, the temperature of the process, and also on the structure of the pharmacologically active modifier acid. The thermal stability of polymeric copper(II) complexes increases with the introduction of an organic complexone into the polysaccharide and with a decrease in the degree of pectin methoxylation.