Complexation thermodynamics and structural studies of trivalent actinide and lanthanide complexes with DTPA, MS-325 and HMDTPA
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Punam Thakur
Abstract
The protonation constants of DTPA (diethylenetriaminepentaacetic acid) and two derivatives of DTPA, 1-R(4,4-diphenyl cyclohexyl-phosphonyl-methyl diethylenentriaminepentaacetic acid (MS-325) and (R)-hydroxymethyl-diethylenentriaminepentaacetic acid (HMDTPA) were determined by potentiometric titration in 0.1 M NaClO4. The formation of 1 : 1 complexes of Am3+, Cm3+ and Ln3+ cations with these three ligands were investigated by potentiometric titration with competition by ethylenediaminetetraacetic acid (EDTA) and the solvent extraction method in aqueous solutions of I=0.10 M NaClO4. The thermodynamic data of complexation were determined by the temperature dependence of the stability constants and by calorimetry. The complexation is exothermic and becomes weaker with increase in temperature. The complexation strength of these ligands follows the order: DTPA ≈ HMDTPA > MS-325. Eu3+/Cm3+ luminescence, EXAFS (Extended X-ray Absorption Fine Structure) and DFT (Density Functional Theory) calculations suggest that all three ligands are octadentate in the complex. In the complex, M(L)2− (L = DTPA, MS-325 and HMDTPA). The M3+ binds via five carboxylates oxygen atoms, three nitrogen atoms, and the complex contains one water of hydration.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Articles in the same Issue
- Cross section measurements of a few threshold reactions induced by fast neutrons from an Am/Be source: integral tests of differential neutron reaction cross section data
- Prediction of the thermal release of transactinide elements (112 ≤ Z ≤ 116) from metals
- Complexation thermodynamics and structural studies of trivalent actinide and lanthanide complexes with DTPA, MS-325 and HMDTPA
- Synthesis and characterization of thorium, uranium and cerium oxide nanoparticles
- Improved radioanalytical method for the simultaneous determination of Th, U, Np, Pu and Am(Cm) on a single TRU column by alpha spectrometry and ICP-MS
- Electrochemical reduction of U(VI) in H2SO4 at gold nanoporous film electrode
- The redox chemistry of neptunium in γ-irradiated aqueous nitric acid
- The incorporation of europium into apatite: anew explanation
- Instrumental neutron activation analysis for the study of size-fractionated airborne particulate matter samples
