The importance of the active complexes of 6 - mercaptopurine with Bi(III) with regards to kinetics and electrode mechanism changes in the presence of non-ionic surfactants

Influence of Mixed 6-Thioguanine-Nonionic Surfactant Adsorption Layers on Kinetics and Mechanism of Bi(III) Ion Electroreduction

“…With an increase in the concentration of both Tween 80 and Triton X-100, the ΔE ac increase which indicates slowing down of the electrode process is observed [10]. Similar dependences were observed for the Bi-6-mercaptopurine-Tween 80 and Bi-6-mercaptopurine-Triton X-100 [6]. This was explained by the formed mixed adsorption layers whose presence changed evidently the dynamics of the Bi(III) ion electroreduction process rate [11,12].…”

“…It should be emphasized that independent of complex-forming properties of the catalyzing substance, its adsorption on the electrode [4] shifts the Bi(III) ion complexation equilibrium favorably. Moreover, Bi(III) ion reduction proceeds in the area of specifically adsorbed 6-thioguanine [6].…”

“…It is worth mentioning that the Bi-6-thioguanine type complex plays a key role as 6-thioguanine dominates in reaching Table 2 The values of current and potential of SWV peaks of 1 × 10 −3 mol • dm −3 Bi(III) ion electroreduction in 2 mol • dm −3 chlorates(VIII) in the presence of 1 × 10 −3 mol • dm −3 6thioguanine and the increasing concentrations of Triton X-100 the adsorption equilibria of the studied mixtures, and what is more, it adsorbs specifically on the electrode surface [18], whereas Tween 80 and Triton X-100 adsorb physically [6,[19][20][21]. With the increasing concentration of surfactants in the electrolyte solution in the presence 1 × 10 −3 mol • dm −3 It should be also emphasized that the stages of dehydration and formation of active complexes in the multi-step Bi(III) ion electroreduction are much faster than those of electron transfer [22,23].…”

“…The results of previous studies pointed out explicitly to the key role of active complexes taking part in electron transition in the electrode process. Further studies of the kinetics and mechanism of Bi(III) ion electroreduction oriented towards the changes of process dynamics affected by formation of the mixed adsorption 6-mercaptopurine-Tween 80 and 6-mercaptopurine-Triton X-100 layers seemed to be extremely interesting taking into account a practical aspect of an investigating mechanism, e.g., action of drugs [6]. Thus, expanding the subject including other drugs applied in antitumorous chemotherapy is justified.…”

Electroreduction of Bi(III) Ions in the Aspect of Expanding the ”Cap – Pair” Effect

“…The introduction of thiopurine derivatives (6-mercaptopurine, 6-thioguanine, azathioprine) to solutions of Bi(III) ions in 2 mol·dm -3 chlorates(VII) indicates an increase in the reversibility of Bi(III) electroreduction [31] (an increase in the SWV peak current for Bi(III) ion electroreduction as well as a simultaneous reduction in the width of SWV peaks at half their height [42][43][44]). The effect of the studied surfactants (Tween 80 and Triton X -100) on the figure of the SWV peaks Bi(III) ions electroreduction in 2 moldm -3 chlorates(VII) at a constant concentration of accelerating substance (1•10 -3 mol•dm -3 6TG, 6MP, AZA) depends on a change in the electrode process reversibility towards inhibition [42][43][44].…”