pH-static titrations for kinetic studies of metal-ligand complex formation: The case example of the reaction between Strontium(II) and DOTA
(2019)
Authors:
Di Marco, V.; Pastore, P.; Tosato, M.; Andrighetto, A.; Borgna, F.; Realdon, N.
Title:
pH-static titrations for kinetic studies of metal-ligand complex formation: The case example of the reaction between Strontium(II) and DOTA
Year:
2019
Type of item:
Articolo in Rivista
Tipologia ANVUR:
Articolo su rivista
Language:
Inglese
Format:
Elettronico
Referee:
Sì
Name of journal:
INORG. CHIM. ACTA
ISSN of journal:
0020-1693
N° Volume:
498
Page numbers:
1-7
Keyword:
kinetics; pH-static titrations
Short description of contents:
The theory of pH-static (or pH-stat) titrations in kinetic measurements of metal ion+ligand complex formation was resumed, and equations required to fit the
experimental data were derived. This method was applied to study the kinetics of Sr2++DOTA reaction (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid). pH-static titrations were performed at various pH (from 4.00 to 6.00) and temperatures (5, 15, and 25 °C) and at a constant ionic strength of (Na)Cl
0.15 mol/L. The complex formation involved either a rapidly formed intermediate species which then gave the final complex, or the direct metal+ligand reaction.
The corresponding equilibrium constant β(os) and kinetic constants k(os) (first order) and k (second order) were obtained. Both k and k(os) increased by increasing pH and temperature. Kinetic data were recorded by pH-static titrations also for Ni2++DOTA reaction, and other kinetic results were obtained by using a more commonly employed method, proposed by Kasprzyk and Wilkins [S. P. Kasprzyk and R. G. Wilkins, Inorg. Chem., 1982, 21, 3349], which however appears to be theoretically incorrect. The comparison between the kinetic results for Sr2++DOTA and Ni2++DOTA reactions obtained by pH-static titrations, by the Kasprzyk/Wilkins method, and by the well-established spectrophotometric method (literature data), indicated that the Kasprzyk/Wilkins method should be used with caution as sometimes its systematic errors can be statistically relevant with respect to the typical precision of kinetic data
Di Marco, V.; Pastore, P.; Tosato, M.; Andrighetto, A.; Borgna, F.; Realdon, N.,
pH-static titrations for kinetic studies of metal-ligand complex formation: The case example of the reaction between Strontium(II) and DOTA«INORG. CHIM. ACTA»
, vol. 498
, 2019
, pp. 1-7