Influence of the platform in multicoordinate ligands for actinide partitioning

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 approximate to 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 (CTV6PICO S-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.