A voltammetric study on the speciation and stability constants for iminodisuccinic acid with selected transition metal ions

• Published in: Chemical speciation and bioavailability Vol. 18; no. 3; pp. 85 - 93
• Main Authors: Polhuis, Michael, Katata, Lebogang M., Crouch, Andrew M.
• Format: Journal Article
• Language: English
• Published: St. Albans Taylor & Francis 01.01.2006; Taylor & Francis Ltd
• Subjects: L-arginine; L-histidine; micelle; nickel; speciation
• ISSN: 0954-2299; 2639-5932; 2047-6523; 2639-5940
• DOI: 10.3184/095422906782146230

The stability constants for complexes between biodegradable racemic iminodisuccinic acid (H 4 IDS) and various metal ions have been determined by cyclic voltammetry at a glassy carbon microelectrode. Measured data compared favourably to the same values determined by potentiometric methods of titration, reiterating the utility of cyclic voltammetry as a facile means for collecting complex stability thermodynamic data. Speciation data of the investigated metal-ligand complexes were subsequently determined by applying these measured constants in a thermodynamic database, the Joint Expert Speciation System (JESS). A semi-empirical molecular orbital study of complex stabilities was also carried out in vacuo on H4IDS and its homologous series. Relative complex stabilities were determined by making use of isodesmic equations and were found to increase with an increase in the size of the chelate rings formed.