Metal complex formation by nicotianamine, a possible phytosiderophore

Abstract

The acid dissociation constants of nicotianamine (1) (pK 1 =6.97, pK 2 =9.13, pK 3 =9.75; 0.1 M KClO 4, 25°C) and the stability constants for its 1:1 complexes with bivalent metal ions (log K Cu =18.6, log K Ni =16.1, log K Co =14.8, log K Zn =14.7, log K Fe =12.1, log K Mn =8.8, log K Mg ≈4.5; 0.1 M KClO 4, 25°C) were determined using potentiometric titrations in aqueous solution. Fe(III)-nicotianamine complexes were not detected under the same experimental conditions. © 1983 Birkhäuser Verlag.