Mechanisms of Reactions of Ce(III)DOTA with Radicals in Aqueous Solutions
2Chemistry, Ben-Gurion University of the Negev, Beer-Sheva
3Nuclear Energy Division, Radiochemistry & Processes, CEA, Bagnols-Sur-Ceze
4Chemical Sciences Department and the Schlesinger Family Center for Compact Accelerators, Radiation Sources and Applications, Ariel University, Ariel
Recent studies have shown that DOTA stabilizes thermodynamically both Ce(III) (log K= 23.4)1 and Ce(IV) (log K= 35.9)2, shifting cathodically the CeIV/III couple to +0.65V vs. SCE , a stabilization of ~ 13 orders of magnitude compared to its aqueous analogue2.
As such we decided to study the reactions of Ce(III)DOTA with several radicals, oxidizing agents: .OH; .CH3; .OOCH3 (given in the exact order of the redox potentials, .OH –the strongest), analyze the products –compare to the reported electrochemical and chemical oxidized cerium complex.
The radicals were produced by continuous radiolysis in aqueous N2O saturated solutions (DMSO present for .CH3; .OOCH3 and 50% v/v O2 present for .OOCH3.). The spectra of the products clearly show the formation of long lived Ce(IV)DOTA(pH dependent) species in the case of .OH and .OOCH3. In the case of peroxyl radicals the main organic product is methanol, different of the main product of the reactions of DOTA and DyDOTA (not redox active) with the same radical, where formaldehyde is the main product. In the case of methyl radicals the ratio CH4/C2H6 is similar for Ce(III)DOTA, DyDOTA and DOTA indicating an H abstraction mechanism from DOTA as the main path. Detailed data will be presented.
- Burai et al., J.Chem.Soc.Dalton Trans. 1998, 443.
- Y. Moiseev et al., J.Coord.Chem. 2016, 69(19),2895
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