Chapter 4
Technetium Coordinated by Organic
Ligands in Aqueous and Nonaqueous
Solutions
Technetium organic complexes are explored mainly in the context of their application in nuclear medicine as imaging agents. It is known that drugs biodistribution
strongly depends on the charge of the species. As an example, reduction of Tc
species by, e.g., glutathione or thioredoxin proteins to neutral or opposite charged
species may result in unwanted loss of radiopharmaceutical efficiency and the target
specificity. The electrochemical studies on Tc complexes may provide information
very helpful in prediction of their behavior in, e.g., fluids present in a human body.
As an example, the determination of the redox potentials of selected Tc forms is
important for evaluation of their suitability for medical applications. However, in
contrast to inorganic technetium compounds only a handful of papers deal with
studies on electrochemical properties of technetium ions coordinated by organic
ligands in aqueous and nonaqueous solutions. Further on, these papers usually report
the results of electrochemical or spectroelectrochemical measurements only as an
addition to the results of other methods applied as the main ones. The cycle of works
by Deutsch, Heinemann and coworkers, which focus exclusively on electrochemical
studies on phosphino-Tc(III) complexes is an exception from the rule (e.g., Hurst
et al. 1981; Ichimura et al. 1984, 1985; Kirchhoff et al. 1987, 1988; Konno et al.
1988; Wilcox and Deutsch 1991). Other examples of papers that are focused on
electrochemical studies of discussed Tc species include works by Refosco et al. (e.g.
1988) who analyzed oxo-technetium(V) complexes containing Schiff bases ligands
and works by Pinkerton and Heineman whose paper deals with an analysis of the
electroreduction of pertechnetates in phosphonate media (Pinkerton and Heineman
1983).
Cyclic voltammetry is the technique most common applied in studies on Tc
compounds stability. It allows determining the half-wave potential, E 1/2 , of the
considered redox system. The redox properties of the technetium organic complexes
discussed later in this Chapter are briefly summarized in Table 4.3.
© Springer Nature Switzerland AG 2021
M. Chotkowski and A. Czerwi´ nski, Electrochemistry of Technetium,
Monographs in Electrochemistry, https://doi.org/10.1007/978-3-030-62863-5_4
69
Technetium Coordinated by Organic
Ligands in Aqueous and Nonaqueous
Solutions
Technetium organic complexes are explored mainly in the context of their application in nuclear medicine as imaging agents. It is known that drugs biodistribution
strongly depends on the charge of the species. As an example, reduction of Tc
species by, e.g., glutathione or thioredoxin proteins to neutral or opposite charged
species may result in unwanted loss of radiopharmaceutical efficiency and the target
specificity. The electrochemical studies on Tc complexes may provide information
very helpful in prediction of their behavior in, e.g., fluids present in a human body.
As an example, the determination of the redox potentials of selected Tc forms is
important for evaluation of their suitability for medical applications. However, in
contrast to inorganic technetium compounds only a handful of papers deal with
studies on electrochemical properties of technetium ions coordinated by organic
ligands in aqueous and nonaqueous solutions. Further on, these papers usually report
the results of electrochemical or spectroelectrochemical measurements only as an
addition to the results of other methods applied as the main ones. The cycle of works
by Deutsch, Heinemann and coworkers, which focus exclusively on electrochemical
studies on phosphino-Tc(III) complexes is an exception from the rule (e.g., Hurst
et al. 1981; Ichimura et al. 1984, 1985; Kirchhoff et al. 1987, 1988; Konno et al.
1988; Wilcox and Deutsch 1991). Other examples of papers that are focused on
electrochemical studies of discussed Tc species include works by Refosco et al. (e.g.
1988) who analyzed oxo-technetium(V) complexes containing Schiff bases ligands
and works by Pinkerton and Heineman whose paper deals with an analysis of the
electroreduction of pertechnetates in phosphonate media (Pinkerton and Heineman
1983).
Cyclic voltammetry is the technique most common applied in studies on Tc
compounds stability. It allows determining the half-wave potential, E 1/2 , of the
considered redox system. The redox properties of the technetium organic complexes
discussed later in this Chapter are briefly summarized in Table 4.3.
© Springer Nature Switzerland AG 2021
M. Chotkowski and A. Czerwi´ nski, Electrochemistry of Technetium,
Monographs in Electrochemistry, https://doi.org/10.1007/978-3-030-62863-5_4
69