Speciation Studies of Binary and Ternary Complexes Formed with Fe(II) Ion, Picolinic Acid, and Several Amino Acids

Abstract

In this study, we investigate the chemical speciation of ternary complex systems involving Fe(II) ions, picolinic acid (HPic), and various amino acids, including α-alanine (HαAla), βalanine (HβAla), glycine (HGly), leucine (HLeu), lysine (HLys), methionine (HMet), phenylalanine (HPhe), serine (HSer), threonine (HThr), valine (HVal), proline (HPro), and histidine (H 2 His). Potentiometric titrations were conducted in an aqueous solution at 25 °C using a 1 mol dm −3 NaCl solution as the ionic medium. Data analysis was performed using the least-squares program LETAGROP. Our study also encompasses the investigation of Fe(II) hydrolysis products (hydroxylated complexes) and binary complexes formed by Fe(II) with picolinic acid and individual amino acids, all in aqueous solution at 25 °C, employing a 1.0 mol dm −3 NaCl medium. Species distribution diagrams were generated, and the relative stability parameter Δlog 10 K was calculated. These findings are significant for the potential design and application of novel Fe(II) complexes in various fields.