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<b>Abstract</b>— <p>Coordination compounds of inorganic cations with biologically active substances are of considerable interest because they have better defined pharmacological properties than do free ligands. Immobilization of coordination compounds in ion exchangers makes it easier to reach required pharmacokinetics, offers significant prospects in issues related to the conservation and storage of bioactive substances, and allows for targeted delivery of an active component to a site of disease. Previously, we studied ligand sorption of pyridine-3-carboxylic acid from aqueous solution on the Cu(II) form of the Dowex-50 cation exchange resin. The purpose of this work is to demonstrate the feasibility of immobilizing pyridine-2-carboxylic acid and copper(II) in a Dowex-50-type styrene divinylbenzene-based sulfonic cation exchange resin; investigate the equilibrium distribution of the components between the Dowex-50 sulfonic cation exchange resin and an aqueous solution containing pyridine-2-carboxylic acid and copper(II) cations; and demonstrate the feasibility of precalculating the equilibrium composition of an aqueous solution of a pyridine-2-carboxylic acid + copper salt mixture for obtaining a Dowex-50 sulfonic cation exchange resin counter ion composition, which is of interest for optimizing industrial processes for the preparation of encapsulated drugs based on pyridine carboxylic acids and inorganic cations. The equilibrium distribution of the components between aqueous pyridine-2-carboxylic acid and copper nitrate solutions and Dowex-50 sulfonic cation exchange resin has been studied by a dynamic method at a temperature of 298 K. With allowance for the concentrations of the components in solution and their ability to participate in cation exchange reactions, the working pH range of the equilibrium solutions was chosen to be 2.0–2.5. The results we obtained lead us to conclude that, in multicomponent heterophase systems consisting of the Dowex-50 sulfonic cation exchange resin and aqueous pyridine-2-carboxylic acid and copper nitrate solutions, equilibrium complexation and ion exchange reactions take place. We demonstrate that, using selectivity coefficients of binary ion exchanges and [H<sub>2</sub>L]<sup>+</sup> and [CuL]<sup>+</sup> complexation constants, one can precalculate equilibrium ionic compositions of the solution and Dowex-50 sulfonic cation exchange resin. The Dowex-50 sulfonic cation exchange resin can probably be proposed as a container for the preparation of medications based on pyridine-2-carboxylic acid and copper(II) cations.</p>

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Ion Exchange in the DOWEX 50 Sulfonic Cation Exchange Resin–Aqueous Cu(NO3)2 Solution–Pyridine-2-Carboxylic Acid System

  • 期刊论文

  • 发表日期：

    2025年6月1日

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  • H. N. Altshuler,
  • V. N. Nekrasov,
  • O. H. Altshuler

摘要

Abstract—

Coordination compounds of inorganic cations with biologically active substances are of considerable interest because they have better defined pharmacological properties than do free ligands. Immobilization of coordination compounds in ion exchangers makes it easier to reach required pharmacokinetics, offers significant prospects in issues related to the conservation and storage of bioactive substances, and allows for targeted delivery of an active component to a site of disease. Previously, we studied ligand sorption of pyridine-3-carboxylic acid from aqueous solution on the Cu(II) form of the Dowex-50 cation exchange resin. The purpose of this work is to demonstrate the feasibility of immobilizing pyridine-2-carboxylic acid and copper(II) in a Dowex-50-type styrene divinylbenzene-based sulfonic cation exchange resin; investigate the equilibrium distribution of the components between the Dowex-50 sulfonic cation exchange resin and an aqueous solution containing pyridine-2-carboxylic acid and copper(II) cations; and demonstrate the feasibility of precalculating the equilibrium composition of an aqueous solution of a pyridine-2-carboxylic acid + copper salt mixture for obtaining a Dowex-50 sulfonic cation exchange resin counter ion composition, which is of interest for optimizing industrial processes for the preparation of encapsulated drugs based on pyridine carboxylic acids and inorganic cations. The equilibrium distribution of the components between aqueous pyridine-2-carboxylic acid and copper nitrate solutions and Dowex-50 sulfonic cation exchange resin has been studied by a dynamic method at a temperature of 298 K. With allowance for the concentrations of the components in solution and their ability to participate in cation exchange reactions, the working pH range of the equilibrium solutions was chosen to be 2.0–2.5. The results we obtained lead us to conclude that, in multicomponent heterophase systems consisting of the Dowex-50 sulfonic cation exchange resin and aqueous pyridine-2-carboxylic acid and copper nitrate solutions, equilibrium complexation and ion exchange reactions take place. We demonstrate that, using selectivity coefficients of binary ion exchanges and [H2L]+ and [CuL]+ complexation constants, one can precalculate equilibrium ionic compositions of the solution and Dowex-50 sulfonic cation exchange resin. The Dowex-50 sulfonic cation exchange resin can probably be proposed as a container for the preparation of medications based on pyridine-2-carboxylic acid and copper(II) cations.