Influence of the platform in multicoordinate ligands for actinide partitioning

Abstract

Multicoordinate ligands based on the trityl, C-pivot, and CTV platforms and the ligating groups CMPO, DGA, PICO, and MPMA were synthesized and studied for their extraction properties. The extraction efficiencies of these multicoordinate ligands are largely influenced by the properties of the platform. The D_Am values follow the order CTV6 > trityl ≈ C-pivot > CTV3 > CTV0 with a maximum for CTV6CMPO of D_Am = 30 (S_Am/Eu = 1.4, c_L = 10^–4 M, 3 M HNO₃). There is a strong relationship between the D_Am values, increasing in the order of CTV0CMPO < CTV3CMPO < CTV6CMPO, and the ‘mobility’ of their CMPO groups. The S_Am/Eu values are less influenced by the platform and range between 0.2 and 2.0, though they can reverse under the influence of the HNO₃ concentration (CTV6PICOS_Am/Eu = 0.7 at 0.001 M HNO₃ to 1.2 at 0.01 M HNO₃) or by changing the platform (CTV(0, 3 or 6)MPMA from S_Am/Eu = 0.4 to 1.6 for tritMPMA both at 0.001 M HNO₃). For the CMPO derivatives the S_Am/Eu values are most consistent, ranging from 1.4 to 1.8.